Computer operated sewing machine with a mode switching function

In a sewing machine provided with a needle position adjusting device to position a needle relative to a basic line, a switching arrangement is provided to switch the needle position adjusting means from a needle amplitude adjusting mode to a mode of adjusting the needle basic line, whereby one adjusting device may be used as a needle amplitude adjusting device for ordinary stitching patterns and as a needle basic line-adjusting device for specific stitching patterns.

FIELD OF THE INVENTION 
The present invention relates to a computer operated sewing machine, and 
more particularly to a sewing machine provided with a mode switching 
function for a needle position adjusting device to switch the same in 
response to a selected pattern to be stitched. 
BACKGROUND OF THE INVENTION 
In many stitchings to be carried out by guiding a fabric to a needle, a 
blindstitching is typical, and the invention will be explained with 
reference to this stitching. 
As shown in FIG. 7 and as generally known, a blindstitched pattern has a 
predetermined width W between a left needle dropping position L and a 
right needle dropping position R. Further it is generally known that the 
left needle dropping position L is a reference along which is guided an 
end part of the upper fold of fabric to be sewn as shown in FIG. 8. 
It is however required that the left and right needle dropping positions L, 
R are changed in dependence upon the thickness of a fabric. So far it has 
been done as follows: 
In FIGS. 9a to 9c, a basic line of needle position is shown by "X" which 
corresponds to one of the L, M and R needle positions as generally known. 
If the basic line X is set to the left needle dropping position L as shown 
in FIG. 9(a), the left needle dropping position L is fixed, and the right 
needle dropping position R is variable as shown at R1, R2, R3 relative to 
the left needle dropping position L. 
If the basic line X is set to the right needle dropping position R as shown 
in FIG. 9(b), the right needle dropping position R is fixed, and the left 
needle dropping position L is variable as shown at L1, L2, L3 relative to 
the right needle dropping position R. 
If the basic line X is set to the middle needle position M as shown in FIG. 
9(c), the left and right needle dropping positions L, R are varied at the 
same ratio with respect to the middle position M. 
The fabric F is folded in the manner as shown in FIGS. 10(a) to 10(c) to 
provide therein an upper fold F7, and a lower fold F2 to be blind-stitched 
thereat, and the edge of the upper fold F1 is set laterally to a guide G 
of a blind stitching presser foot 47 as shown in Figs.8, 13, 16 and 17, in 
which the presser foot 47 is pressed against the upper and lower folds F1, 
F2 of the fabric F and the guide G is pressed against the lower fold F2. 
The guide G may be fixed to the presser foot 7 as shown in FIG. 13 or may 
be adjustable laterally of the presser foot 47 as shown in Figs.16 and 17. 
Then it is required that the left needle dropping position L is set to an 
appropriate position on the fabric F where a needle penetrates the upper 
and lower folds F1, F2 of the fabric F as shown in FIG. 8. More precisely 
the appropriate position is represented by (a) in FIG. 11, the position 
being slightly spaced inward from the edge of the upper fold F, so that 
the formed stitches S may not be conspicuous as shown in FIG. 12(a) when 
the uppermost part of the fabric F is unfolded. The stitches S in FIG. 
12(a) are shown in contrast to the conspicuous stitches S1 (FIG. 12b) 
which are undesirous and may be formed when the left needle dropping 
position L is set to the position (b) on the fabric F in FIG. 11 where the 
needle is spaced far away inward from the edge of the upper fold F1, as 
compared with the needle position (a). Moreover such conspicuous stitches 
S1 will cause shrinkage of the fabric when the latter is unfolded. On the 
other hand, if the left needle dropping position L is set to a position 
(c) in FIG. 11 where the needle is spaced outward from the edge of the 
upper fold F1, the blindstitches are not formed on the upper fold F1 and 
result in failure of the blindstitching function as shown in FIG. 12(c). 
With respect to the formation of blindstitches, there have been generally 
three types of operation as follows. 
(1) A blindstitching presser foot having a guide fixed thereto is employed 
in combination with a sewing machine storing a blindstitch pattern of a 
predetermined amplitude. 
(2) A blindstitching presser foot having a guide fixed thereto is employed 
in combination with a sewing machine storing a blindstitch pattern, the 
amplitude and basic line of which may be varied. 
(3) A blindstitching presser foot having a guide provided as being 
adjustable laterally thereof is employed in combination with a sewing 
machine storing a bilndstitch pattern, at least the amplitude of which may 
be varied. 
In case of item (1), the blindstitching presser 47 having the guide G fixed 
thereto as shown in FIG. 13 is employed in combination with the sewing 
machine as mentioned in the item (1). In this case, the needle positions 
are constant at both sides of the guide G. However because of the possible 
divergences in precision of parts in each of the sewing machine, generally 
the guide G is mounted on the presser foot 47 such that the needle may 
drop at the left position L where the needle is sufficiently spaced inward 
from the edge of the upper fold F1 to secure the correct formation of 
blindstitches. More precisely, the dimension (d) in FIG. 8 is amplified 
more than normally required, and this often causes the conspicuous (large) 
stitches S1 which are undesired. 
In case of item (2), the blindstitches may be produced in the manner as 
shown in FIGS. 9(a), 9(b) or 9(c), in which the amplitude may be varied 
with respect to the basic line as shown at L, R or M as described herein 
above. In case of FIG. 9(a), the right needle dropping position R may be 
variably set from the fixed left needle dropping position L. However as 
the distance (d) in FIG. 8 is predetermined by the guide G with an 
amplitude dimension, for the reason as mentioned above, this may cause 
conspicuous stitches S1. In case of FIG. 9(b), the left needle droping 
position L may be variably set from the fixed right needle dropping 
position R. However as distance (d) in FIG. 8 is predetermined by the 
guide G with an amplitude dimension, this may cause the lower fold F2 to 
loose by of a considerable size of dimension E to the left loose as shown 
in FIGS. 14 and 15. In case of FIG. 9(c), if one of the left and right 
needle dropping positions L, R, the other the needle dropping positions is 
varied, and therefore the defects as mentioned in item 1 and in case of 
FIG. 9(b) may be caused. 
In case of item (3), the guide G may be adjusted laterally of the presser 
foot 47 as shown in FIGS. 16 and 17 to variably determine the distance (d) 
of the blindstitch in FIG. 8. However the mechanical play of the presser 
foot structure will fail to stabilize the guide G in the set position 
relative to the presser foot 47 resulting in divergences of the 
blindstitches formed on the fabric. 
The above mentioned conventional mode of stitching is insufficient with 
respect to required conditions of the formation of blindstitches, due to 
the defects as described above since it has been desired that, 
(1) the fabric guiding parts are stable; 
(2) the darning amplitude is made as small as possible; and 
(3) the needle dropping position may be adjusted with respect to the fabric 
guiding. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved computer 
operated sewing machine. 
In a sewing machine which stores stitch control signals in an electronic 
memory of a microcomputer, the present device is provided with a fixed 
fabric guide and an instrument which switches as a needle position 
adjusting means from an adjusting mode of adjusting a needle amplitude to 
an adjusting mode of adjusting a basic line of a needle with respect to 
the selection of a specific stitching pattern to be used in association 
with a fabric presser foot which guides the fabric to a needle. 
By selection of the blindstitching, it is also possible to set the needle 
in a predetermined amplitude suitable to the blindstitching. For 
practicing the blindstitching, the fabric is guided to a fabric guide part 
of the presser foot, and the position of the needle basic line is adjusted 
by means of the needle position adjusting device which has been switched 
to the adjusting mode of the needle basic line. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
The present invention will be explained in detail with reference to the 
attached drawings. 
FIG. 1 shows a perspective view of a sewing machine incorporating a 
mode-switching instrument for producing blindstitches according to the 
invention. Referring to FIG. 4 it will be seen that a machine frame 1 of 
the sewing machine is provided with the needle bar 3 possitioned movably 
vertically and connected to a drive shaft 2 which is in turn connected to 
a drive part (not shown) and subjected to rotation. The needle bar 3 is 
fixed in a needle bar holder 10 which is inserted at its upper and lower 
parts in a needle bar supporter 11. A drive shart 2 is rotatably supported 
in the machine frame 1, and a crank 7 is provided at the end of the drive 
shaft 2. A crank rod 9 is rotatably connected to an end of a needle bar 
crank 8 which is secured to the end of the crank 7. The needle bar 
supporter 11 is mounted on a shaft 12 secured to the machine frame 1, and 
is restricted in vertical movements but is only rotatable. The needle bar 
supporter 11 is connected at its end to one end of a rod 13 which is 
connected, via a link 16, at its other end to an arm 15 secured on an 
output shaft 14a of a needle amplitude stepping motor 14. 
As shown in FIG. 1, the machine frame has, at its lower part, a needle 
plate 18 formed with a needle dropping hole 18a for passing a needle 17 
secured to the needle bar 3 at its end portion. 
Numeral 19 is a feed dog which rises from and falls into the feed dog 
groove 18b formed in the needle plate 18 (FIG. 1) and feeds a fabric in 
synchronism with a presser foot 20 (FIG. 1). The feed dog 19 is mounted to 
a horizontal feed arm 21 driven by the drive shaft 2. The movement of the 
horizontal feed arm 21 is adjusted by turning the same, and a turning 
angle adjusting member 22 is fixed on the end of an adjusting shaft 23 so 
that the transmission amount of rotation to the horizontal feed arm 21 is 
adjusted by rotating the member 22. An arm 24 secured on the end of the 
shaft 23 is connected to a crank 26 mounted on the output shaft of a feed 
adjustment stepping motor 25 secured to the machine frame 1. 
Numeral 28 designates a loop taker device as a thread loop hooking means, 
rotatably supported in the machine frame 1 under the needle plate. A gear 
30 is secured on a shaft 29 to be rotated in synchronism with the needle 
bar 3, while a gear 31 is secured under the loop taker device 28, and 
these gears 30 and 31 are meshed with one another to transmit the rotation 
to the loop taker device. 
As is seen in FIG. 1, the machine frame 1 is attached with a scale panel 4 
on which there are furnished a key board 5 of a pattern selecting device 
and a key board 6 for manually adjusting the needle position and feed 
amount. 
A central device for controlling the electronic sewing machine is seen in 
FIG. 5, and will be explained with operations will be explained with 
reference to FIG. 6. 
A pattern to be stitched is selected by operating the pattern selecting key 
board 5 and is read out from a memory 32 of pattern generating information 
and stored in a memory 33 of the selected pattern generating information. 
The pattern stored in the memory 32 is set at predetermined values of the 
needle amplitude and feed amount. 
Patterns to be stitched include ordinary patterns as seen in FIG. 19 and 
specific stitches which require to control a fabric guiding position of 
the presser foot and a needle position as seen in FIG. 18. Specific 
patterns are accompanied with a signal showing that the pattern is 
specific. 
Whether the selected pattern is specific or not is discriminated by a 
discriminating means 34 of specific patterns. If the pattern to be 
stitched is an ordinary one as seen in FIG. 19, an input from a key 35 of 
adjusting the needle position of the key board 6 is switched to a device 
37 for manually adjusting the needle amplitude amount, that is, a device 
including the needle position adjusting key 35 is switched to an amplitude 
mode. 
The amplitude amount is increased more than a predetermined amount by 
operating +key 35a of the needle position adjusting key 35, and is 
decreased by operating -key 35b (FIG. 3. With respect to the feed amount, 
a feed adjusting key 38 is operated, +key 38a and -key 38b for generating 
the adjusted patterns are operated, a predetermined feed is adjusted by 
means 39 and is stored in a memory 40 as shown in FIG. 5. 
FIG. 5 further illustrates a needle position adjusting motor 14 and a feed 
adjusting motor 25 which are driven by a stitching order in response to a 
timing signal generated by rotation of the sewing machine, following the 
patern generating information stored in the memory 40, and the needle 
position and the feed are controlled to form stitching patterns. 
If the selected pattern is a specific one as seen in FIG. 20, an input from 
the needle position adjusting key 35 by a discriminating signal from the 
specific pattern-discriminating means 34 is switched to the needle basic 
line-manually adjusting means 41 as shown with a dotted line in FIG. 5 by 
means of a switching means 36. That is, the needle position adjusting 
device is switched to the needle basic line mode. 
"Blindstitch" as the specific pattern as seen in FIG. 2 is memorized with a 
predetermined needle basic line position R and a fixed amplitude amount W. 
The needle basic line position R shown in FIG. 20 is moved to the right by 
the +key 35a of the needle position adjusting key 35 as the fixed 
amplitude amount W is as shown with the dotted line, and is moved to the 
left by the -key 35b as the fixed amplitude amount W is as shown with a 
chain line. 
The feed amounts in the ordinary stitching pattern are the same in a case 
of the ordinary stitching, and the +key 38a and the -key 38b of the feed 
adjusting key 38 are operated to adjust the predetermined feed amount by 
the feed amount-manually operating device 39 and this feed amount is 
stored in the adjusting pattern generating information memory 40. A needle 
position adjusting motor 14 and a feed adjusting motor 25 are driven by a 
stitching order in response to a timing signal generated by rotation of 
the sewing machine, following the pattern generating information stored in 
the memory 40, and the needle position and the feed are controlled. 
For forming the blindstitch as shown in FIG. 18, a blindstitching presser 
foot 47 is employed as shown in FIG. 13 which has the fixed fabric guide, 
and the blindstitching pattern shown with at 42 in FIG. 2 is selected by 
the pattern selecting key board 5 to read out a pattern generating 
information from the memory 32 and store it in the memory 33. The needle 
dropping left position is adjusted in that the position R0 (FIG. 18) of 
the right basic line as the position of needle basic line is adjusted by 
operating the +key 35a or the -key 35b of the needle position adjusting 
key 35. 
It wil be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of sewing 
machines differing from the types described above. 
While the invention has been illustrated and described as embodied in a a 
sewing machine, it is not intended to be limited to the details shown, 
since various modifications and structural changes may be made without 
departing in any way from the spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.