Impact printer with means for adjusting the associated print hammer

An impact-type, printing apparatus which is readily adjusted to enable the impact face of the associated print hammer to be precisely located with reference to the plane of a character (or a typewheel) to be printed to enable printing in special fonts like E13-B. First and second eccentric members and a separate moveable member are used to provide the adjustments necessary for the precise location of the impact face.

BACKGROUND OF THE INVENTION 
This invention relates to impact printers, and more specifically, it 
relates to a means for adjusting the impact face of the associated print 
hammer so as to be precisely positioned at impact and thereby be capable 
of accurately printing characters in special printing styles or fonts, 
like E13-B, for example. 
During the processing of financial documents, like checks, by financial 
institutions, like banks, a point is reached in the processing at which 
the monetary amount of each check is printed on the front of the check in 
the area below the signature line; this process is generally referred to 
as "encoding". The monetary amount is printed on the check in a 
magnetic-type ink which is generally referred to as "MICR" ink, with 
"MICR" being an acronym for "magnetic ink character recognition." Banks in 
the U.S.A. generally use the E13-B font or style mentioned in the encoding 
process. 
Because the characters produced in the E13--B font are read magnetically, 
it is necessary that the characters be precisely printed in MICR ink in 
order that they be read accurately at subsequent processing operations. If 
the impact face of the print hammer is not properly aligned with the 
character to be printed during the printing operation, improperly printed 
characters will result, and misreading or non-reading of data will occur 
at subsequent processing operations. 
Some known techniques for aligning the impact face of the print hammer of 
an impact-type printer with the character to be printed are performed by 
using shims, bending the print hammer beam, and changing the pivot point 
of the print hammer beam. These known techniques require a fairly-skilled 
operator to perform, and the techniques are time-consuming. 
SUMMARY OF THE INVENTION 
The printer apparatus of this invention employs a structure which 
facilitates the mentioned aligning of the impact face of the associated 
print hammer with the character to be printed. 
In addition, the alignment procedure using this invention may be performed 
with operators who are less skilled than the operators who are required to 
utilize the known techniques mentioned. 
In a preferred embodiment, the printing apparatus of this invention 
comprises: a base plate; a printing station including a document track 
which is perpendicular to and secured to said base plate; presenter mean 
located at said printing station for presenting characters to be printed 
in a first plane substantially parallel to said document track and located 
therein; a support plate having a top surface and a bottom surface; a 
print hammer; means for pivotally mounting said print hammer on said 
support plate and also for moving said print hammer in a second plane 
parallel to said top surface of said support plate between non-printing 
and printing positions relative to said printing station; said print 
hammer having an impact plane to cooperate with a character on said 
presenter means to print said character on a document positioned between 
said presenter means and said impact plane when said hammer is moved to 
said printing position; said impact plane having mutually perpendicular 
first and second imaginary axes lying in said impact plane of said print 
hammer; first and second adjustable eccentric means coupled between said 
support plate and said base plate to enable said first imaginary axis of 
said impact plane to be positioned parallel to said first plane when said 
print hammer is in said printing position; said support plate having a 
recess in said bottom surface; a moveable adjusting member slidably 
mounted in said recess next to said base plate to enable said second 
imaginary axis of said impact plane to be positioned parallel to said 
first plane when said print hammer is in said printing position; and 
securing means for securing said first and second adjustable eccentric 
means and said moveable adjusting member in fixed positions when said 
print hammer is in said printing position and when said impact plane is 
parallel to said first plane. 
The advantages mentioned, and others, will become more readily understood 
in connection with the following description, claims, and drawing.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 is a plan view of a printing apparatus made according to this 
invention and designated generally as 10. The apparatus 10 includes a base 
plate 12 on which a document track 14 is located. The document track 14 
has side walls 14A and 14B which are perpendicular to and upstanding from 
the base plate 12. 
The printer apparatus 10 also includes means for moving documents like 
document 16 along the track 14, and this means is shown only schematically 
as document transport 18 (FIG. 2). Printing is effected at the printing 
station 20 which is located along the document track 14. 
The means for presenting characters to be printed at the printing station 
20 is shown as a typewheel 22 in FIG. 2. A positioning mechanism shown 
schematically as 24 is used to rotate or index the typewheel 22 so as to 
present the character to be printed to the impact plane or face 26 of a 
print hammer designated generally as 28. 
The print hammer 28 is pivotally mounted on a pin 30 (FIG. 1) which is 
upstanding from a support plate 32. An actuating coil 34, when energized 
by the controller 36 (FIG. 2), is used to pivot the print hammer 28 in a 
clockwise direction (as viewed in FIG. 1) to move the impact face 26 into 
printing relationship with a character on the type wheel 22, the document 
16, and a ribbon 38 as shown in FIG. 2. A second coil 40, when energized 
by the controller 36, is used to return the print hammer 28 to the home 
position shown in FIG. 2. The print hammer 28 has ferrous members 42 and 
44 thereon to coact with the coils 34 and 40, respectively, as is done 
conventionally. The laminations 46 for the coil 34 are secured to a 
mounting plate 48 which in turn is secured to a block 50 which is part of 
the support plate 32. Similarly, the laminations 52 for the coil 40 are 
secured to a a mounting plate 54 which in turn is secured to the block 50. 
The apparatus 10 includes a position sensor 56 (FIG. 1) which detects the 
leading edge of a document 16 approaching the printing station 20 and also 
includes a ribbon supply mechanism 58, shown only schematically in FIG. 2. 
In the embodiment described, the ribbon 38 is filled with a MICR or 
magnetic ink, and the characters on the typewheel 22 conform to the E13-B 
format or font, for example, as alluded to earlier herein. An input 60 to 
the controller 36 is used to provide the data, like monetary amount, to be 
printed on the document 16. The controller 36 then actuates the 
positioning mechanism 24, which, in turn, indexes the typewheel 22 to 
present the character to be printed. The controller 36 then energizes coil 
34 to pivot the print hammer 28 and thereby move the impact face 26 into 
printing engagement with the character at the printing station 20. 
Thereafter, the actuating coil 34 is de-energized, and the return or 
second coil 40 is energized by the controller 36 to return the print 
hammer 28 to the home position shown in FIG. 1. The document transport 18 
is then energized by the controller 36 to move the document 16 one 
character position in a downstream direction (shown by arrow 62), and 
thereafter, the process described is repeated for the characters to be 
printed. In the embodiment described, the printing or encoding in MICR ink 
is performed on the lower-right, front side of the check 16 under the 
signature line thereon. When the printing apparatus is not in use, a 
tension spring 64 is used to resiliently bias the print hammer 28 to the 
home position against the stop block 66 shown in FIG. 1. 
As alluded to earlier herein, if the impact face 26 of the print hammer 28 
is not parallel to the plane of a character on the type wheel 22 at the 
moment of impact, the MICR character produced thereby will not be 
accurately formed. Because these MICR characters are read magnetically, 
they will not produce the precise, magnetic wave shapes necessary to 
enable them to be read accurately or to be read at all during subsequent 
processing operations when the monetary amount is machine read. As 
previously stated, it is difficult to align the impact face 26 by the 
known techniques mentioned earlier herein. 
The printing apparatus 10 facilitates the aligning of the impact face 26 to 
produce precise characters at the printing station 20. In this regard, the 
support plate 32 (FIGS. 5A, 5B, and 5C) has a top surface 32-T and a 
bottom surface 32-B as shown. The print hammer 28 (shown only in dashed 
outline in FIGS. 5A, 5B, and 5C) is mounted on the support plate 32 for 
movement in a plane which is parallel to the top surface 32-T of the 
support plate 32. Notice, also, that the support plate 32 is tapered in 
thickness, with the end 32-1 which is closest to the document track 14 
being thicker than the opposite end 32-2 (FIG. 1) with regard to the top 
surface 32-T; this is shown by dashed line 33 in FIG. 5A which represents 
an extension of top surface 32-T. In other words, the planes represented 
by top surface 32-T and bottom surface 32-B tend to converge towards the 
right as viewed in FIG. 5A. The means for coupling the support plate 32 to 
the base plate 12 includes two eccentric members designated generally as 
68 and 70 as shown in FIG. 1. The eccentric member 70 is positioned closer 
to the document track 14 than is the eccentric member 68. Because the 
eccentric members 68 and 70 are identical, a discussion of only eccentric 
member 68 will follow. 
The eccentric member 68 (FIGS. 1, 3 and 4) includes an eccentric bushing 
portion 72 which has an outer diameter which is dimensioned to fit within 
the elongated hole 74 (FIG. 4) of the support plate 32. The eccentric 
member 68 also has a hole 76 therein which is offset from the longitudinal 
axis of the bushing portion 72 to provide the displacement indicated by 
arrows 78 and 80 in FIG. 4 for the embodiment being described. A screw 80, 
which slidably fits in the hole 76 and is secured in a threaded hole 81 
(FIG. 3) in the base plate 12, provides the means for securing the 
eccentric member 68 and the support plate 32 in an adjusted, fixed 
position relative to base plate 12. A hex 82 formed on the bushing portion 
72, when rotated with a wrench (not shown), provides for an adjustment of 
the displacement mentioned. 
Another adjustment for the printing apparatus 10 is effected through the 
use of a moveable adjusting member which is designated generally as 84 as 
shown in FIGS. 1 and 5A, for example. The member 84 has a tapered, first 
portion 86 which is complementary to the taper in the area 87 of the 
support plate 32. The member 84 also has an extension 88 having an 
elongated hole 90 therein to loosely receive the adjusting fastener 92. 
The lower side of the support plate 32 has a projection 94, which remains, 
due to area 87 being recessed slightly, to provide some clearance between 
the support plate 32 and the tapered, first portion 86 of the member 84 to 
thereby minimize the friction therebetween when the member 84 is moved 
between the positions shown in FIGS. 5A and 5C. The first portion 86 is 
thinner in thickness at the end located under projection 94, as viewed in 
FIG. 5A, than it is at the end near the extension 88. The fastener 92 is 
threadedly received in a threaded hole 96 in the block 50. The member 84 
is resiliently biased to the position shown in FIG. 5A by a compression 
spring 98. The moveable member 84 is guided towards and away from the 
document track 14 in a recess located in the underside of support plate 
32, with this recess being shown by the dashed lines 100 and 102 in FIG. 
1. 
In order to discuss how adjustments are made to the apparatus 10 to get the 
impact face 26 of print hammer 28 in a desired position, it is useful to 
consider certain imaginary planes and axes. In this regard, a selected 
character on the type wheel 26, when positioned for printing, may be 
considered to lie in an imaginary, vertical plane which is perpendicular 
to the base plate 12 and parallel to the document track 14. The impact 
face 26 of the print hammer 28 may be considered to have first and second 
mutually perpendicular axes thereon, with the first axis being parallel to 
the imaginary, vertical plane mentioned and with the second axis being 
perpendicular to the base plate 12 when the selected character, document 
16, ribbon 38, and impact face 26 of the print hammer 28 are in the 
proper, printing relationship at impact. 
Assume for the moment that the impact face 26 of print hammer 28 is not 
adjusted at all. To adjust the printing apparatus 10, the screws 80 of the 
eccentric members 68 and 70 are loosened to enable the support plate 32 
and the moveable member 84 to be moved to position the impact face 26 
approximately parallel to the imaginary vertical plane mentioned at the 
impact position. After this is done, the screws 80 of the eccentric 
members 68 and 70 are tightened, and a character is printed to determine 
the alignment of the printing apparatus 10. 
FIGS. 6, 7, 8, and 9 show the number 0 or zero as printed by different 
adjustments of the apparatus 10. The zero shown in each of the FIGS. 6-9 
is show in double outline merely to facilitate showing which portions, if 
any, of a character are not printed properly. For example, the zero shown 
in FIG. 7 is printed properly in that the top and bottom, and left and 
right sections, as viewed in FIG. 7, are all of equal density as shaded. 
In FIG. 6, for example, the bottom half of the character is printed, but 
the top half of the character is not printed. In FIG. 9, the right half of 
the character (as viewed in FIG. 9) is printed, but the left side is not. 
Assume that a trial printing is performed by the printing apparatus 10, and 
that the number 0 is printed as shown in FIG. 6. Because the left and 
right halves of the number 0 in FIG. 6 are of equal density, and only the 
top half is not printing, the following adjustment procedure is used. The 
screws 80 of the eccentric members 68 and 70 are loosened to permit the 
moveable member 84 to be advanced towards the document track 14 by 
advancing the screw 92 to move the moveable member 84 to the approximate 
position shown in FIG. 5B. This action adjusts the print hammer 28 so that 
the second axis on the impact face 26 is perpendicular to the base plate 
12 during impact. 
After the adjustment mentioned, the screws 80 of the eccentric members 68 
and 70 are tightened, and the printing apparatus 10 is operated to check 
on the resulting printing. If the characters appear as shown by the number 
0 in FIG. 8, the screws 80 of the eccentric members 68 and 70 are loosened 
again, and the screw 92 is withdrawn from the position shown in FIG. 5C to 
approximately that shown in FIG. 5B. Thereafter the screws 80 are 
tightened, and printing is again performed. If the characters appear as 
shown by number 0 in FIG. 9, no vertical adjustment is necessary; however, 
the eccentric members 68 and 70 will have to be adjusted to bring the 
first axis on the impact face 26 into parallel relationship with imaginary 
plane mentioned. This imaginary plane is also parallel to the plane of 
document 16 shown in FIG. 2. The adjustment to the printing apparatus 10 
is made by first loosening screws 80 of the eccentric member 68 and 70. 
Thereafter, a wrench (not shown) is placed on the hex 82 of the first 
eccentric members 68 and the hex 82 is turned in a way which brings the 
upstream end of support plate 32 (the end containing block 66) closer to 
the document track 14. Thereafter, the screws 80 of the eccentric members 
68 and 70 are tightened to secure the printing apparatus 10 in the 
adjusted position. Printing is again performed, and adjustments, if 
necessary, are made as described by trial and error. 
The printing apparatus 10 as just described provides an easy method of 
adjusting the impact face 26 of the print hammer 28 so as to provide 
precise printing of characters in printing fonts, like E13-B, for example.