PRINT HEAD ASSEMBLY AND METHOD OF MAKING SAME

TETE D'IMPRIMANTE, ET METHODE DE FABRICATION CONNEXE

English Abstract

Docket M-391

PRINT HEAD ASSEMBLY AND METHOD OF MAKING SAME

Abstract of the Disclosure
There is disclosed a method of making a print head
assembly and a print head assembly. The print head assembly
is comprised of one or more subassemblies. Each subassembly
is made up of relatively few parts including a mounting
block having a concave mounting surface, a series of drive
wheels supported at their outer peripheries on the mounting
surface, and a series of printing bands with which the drive
wheels are engaged. The subassemblies can be readily assembled
on a fixture. Thereafter, each subassembly is oriented
relative to side plates to make a print head assembly.

Claims

Docket M-391-C-1

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. Method of making a print head assembly,
comprising the steps of: providing mounting means having a
concave mounting surface, providing supporting means disposed
opposite the concave mounting surface, providing a series of
drive wheels having holes, providing a series of printing bands
each having a plurality of different printing elements, pro-
viding a selector, providing a pair of first and second side
plates with the second side plate having an opening, assembling
the drive wheels and the respective printing bands onto the
mounting means so that the drive wheels are rotatably supported
on the concave mounting surface with their holes in general
alignment and with the printing bands being trained about the
respective drive wheels and the supporting means to provide a
subassembly, and connecting the first and second side plates
to opposite sides of the subassembly in precise orientation
with the selector extending through the opening in the second
side plate and into the holes to engage any selected wheel to
provide an assembly.
2. Method of making a print head assembly,
comprising the steps of: providing mounting means having
a concave mounting surface, providing supporting means
disposed opposite the concave mounting surface, providing a
series of drive wheels having holes, providing a series of
printing bands each having a plurality of different printing
elements, providing a selector, providing a pair of first and
second side plates with the second side plate having an
opening, assembling the drive wheels and the respective
printing bands onto the mounting means so that the drive
wheels are rotatably supported on the concave mounting surface
with their holes in general alignment and with the printing
bands being trained about the respective drive wheels and the
supporting means to provide a subassembly, positioning the
first and second side plates at opposite sides of the sub-
assembly in precise orientation, the selector extending
through the opening in the second side plate and into the
holes in the wheels, and securing the first and second side
plates to the mounting means in said precise orientation to
provide an assembly.

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Docket M-391-C-l

3. Method of making a print head assembly,
comprising the steps of: providing a mounting block having a
concave mounting surface, providing supporting means disposed
opposite the concave mounting surface, providing a series of
drive wheels having holes, providing a series of printing
bands having a plurality of different printing elements,
providing a selector, providing a pair of first and second
side plates with the second side plate having an opening,
assembling the drive wheels and respective printing bands
onto the mounting block so that the drive wheels are rotatably
mounted on the concave mounting surface with their holes in
general alignment and with the printing bands being trained
about the respective drive wheels and the supporting means to
provide a subassembly, positioning the first side plate against
one side of the subassembly, securing the first side plate
to the subassembly, inserting the selector through the opening
in the second side plate, inserting the selector into the
holes in the wheels, positioning the second side plate against
the other side of the subassembly with the end portion of the
selector inserted into the holes in the wheels, and
securing the second side plate to the mounting block to
provide an assembly.
4. Method of making a print head assembly,
comprising the steps of: molding a one-piece mounting block
having a concave mounting surface and a support disposed
opposite the concave mounting surface from moldable plastics
material, providing a series of drive wheels having holes,
providing a series of printing bands each having a plurality
of different printing elements, providing a selector, providing
a pair of first and second side plates with the second side
plate having an opening, assembling the drive wheels and the
respective printing bands onto the mounting block so that the
drive wheels are rotatably supported on the concave mounting
surface with their holes in general alignment and with the
printing bands being trained about the respective drive wheels
and the supporting means to provide a subassembly, and connecting



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Docket M-391-C-l

the first and second side plates to opposite sides of the
subassembly in precise orientation with the selector extending
through the opening in the second side plate into the holes to
engage any selected wheel to provide an assembly.
5. Method of making a print head assembly,
comprising the steps of: molding a one-piece mounting
block having a concave mounting surface and a support disposed
opposite the concave mounting surface from moldable plastics
material, providing a series of drive wheels having holes,
providing a series of printing bands each having a plurality
of different printing elements, providing a selector, providing
a pair of first and second side plates with the second side
plate having an opening, assembling the drive wheels and the
respective printing bands onto the mounting block so that the
drive wheels are rotatably supported on the concave mounting
surface with their holes in general alignment and with the
printing bands being trained about the respective drive wheels
and the supporting means to provide a subassembly, positioning
the first and second side plates at opposite sides of the
subassembly in precise orientation, the selector extending
through the opening in the second side plate and into the
holes in the wheels, and securing the first and second side
plates to the mounting block in said precise orientation to
provide an assembly.
6. Method of making a print head assembly, comprising
the steps of: molding a one-piece mounting block having a
concave mounting surface and a support disposed opposite the
concave mounting surface from moldable plastics material,
providing a series of drive wheels having holes, providing a
series of printing bands having a plurality of different
printing elements, providing a selector, providing a pair of
first and second side plates with the second side plate having
an opening, assembling the drive wheels and respective
printing bands onto the mounting block so that the drive
wheels are rotatably mounted on the concave mounting surface
with their holes in general alignment and with the printing
bands being trained about the respective drive wheels and the
supporting means to provide a subassembly, positioning the

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Docket M-391-C-l

first side plate against one side of the subassembly, securing
the the first side plate to the mounting block, inserting the
selector through the opening in the second side plate,
positioning the second side plate against the other side of
the subassembly with the end portion of the selector inserted
into the holes in the wheels, and securing the second side
plate to the mounting block to provide an assembly.
7. Method of making a print head assembly,
comprising the steps of: providing mounting means having a
concave mounting surface, providing supporting means disposed
opposite the concave mounting surface, providing a series of
drive wheels having holes, providing a series of printing bands
each having a plurality of different printing elements, pro-
viding a selector, providing a pair of first and second side
plates with the second side plate having an opening, assembling
the drive wheels and the respective printing bands onto the
mounting means so that the drive wheels are rotatably supported
on the concave mounting surface with their holes in general
alignment and with the printing bands being trained about the
respective drive wheels and the supporting means to provide a
subassembly, and keying the first and second side plates
to opposite sides of the subassembly in precise orientation
with the selector extending through the opening in the second
side plate into the holes to engage any selected wheel to
provide an assembly.
8. Method of making a print head assembly for
printing at least two lines of data,
making at least two subassemblies having substantially
identical parts, each subassembly being made by molding a
one-piece mounting block having a concave mounting surface and
a support disposed opposite the concave mounting surface from
moldable plastics material, providing a series of drive wheels
having holes for receiving a selector, providing a series of
printing bands each having a plurality of different printing
elements, assembling the drive wheels and the respective
printing bands onto the mounting block so that the drive
wheels are rotatably supported on the concave surface with
their holes in general alignment with the printing bands being

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Docket M-391-C-l

trained about the respective drive wheels and the supporting
means to provide a subassembly, the support supporting a
printing element in a plane which is inclined from the perpendicular
relative to a reference line passing through the center of a
drive wheel and the support;
orienting the subassemblies so that the supports
are disposed close together in the same plane and the reference
lines are inclined with respect to each other.
9. Method of making a print head assembly for
printing at least two lines of data,
making at least two identical subassemblies, each
subassembly being made by molding a one-piece mounting block
having a concave mounting surface and a support disposed
opposite the concave mounting surface from moldable plastics
material, providing a series of drive wheels having holes for
receiving a selector, providing a series of printing bands
each having a plurality of different printing elements,
assembling the drive wheels and the respective printing bands
onto the mounting block so that the drive wheels are rotatably
supported on the concave surface with their holes in general
alignment with the printing bands being trained about the
respective drive wheels and the supporting means to provide a
subassembly, the support supporting a printing element at a
printing position in a plane which is inclined from the
perpendicular relative to a reference line passing through
the center of a drive wheel and the support;
orienting the subassemblies so that both sub-
assemblies are equally and oppositely inclined with respect
to a line extending between the subassemblies and intersecting
the plane of the supports at a right angle and so that the
printing elements at the printing position are in the same plane.
10. Method of making a print head assembly,
comprising the steps of: providing mounting means having a
concave mounting surface, providing supporting means disposed
opposite the concave mounting surface, providing a series of
drive wheels having holes, providing a series of printing bands
each having a plurality of different printing elements, pro-
viding a selector, providing a pair of first and second side




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Docke-t M-391-C-l

plates with the second side plate having an opening, placing
the mounting means and supporting means in a fixture, assembling
the drive wheels and the respective printing bands onto the
mounting means so that the drive wheels are rotatably supported
on the concave mounting surface with their holes in general
alignment and with the printing bands being trained about the
respective drive wheels and the supporting means to provide a
subassembly, removing the subassembly from the fixture, and
connecting the first and second side plates to opposite sides
of the subassembly in precise orientation with the selector
extending through the opening in the second side plate and
into the holes to engage any selected wheel to provide an
assembly.
11. A print head assembly, comprising: mounting
means having a concave mounting surface, a series of drive
wheels rotatably mounted at their outer peripheries on the
concave mounting surface, the drive wheels having holes in
general alignment with each other, supporting means disposed
opposite the concave mounting surface, a series of printing
bands each having a plurality of different printing elements,
the printing bands being trained about the respective drive
wheels and the supporting means to provide a subassembly, a
selector for selectively setting any wheel to advance a
selected printing band, first and second side plates with the
second side plate having an opening for receiving the selector,
and means connecting the first and second side plates to
opposite sides of the subassembly in precise orientation with
the selector extending through the opening in the second side
plate and into the holes in the wheels to provide an assembly.
12. A print head assembly as defined in claim 11,
wherein the connecting means includes means for keying the
first side plate to the mounting means and means for keying the
second side plate to the mounting means.
13. A print head assembly as defined in claim ll,
wherein the connecting means includes means for keying the first
side plate to the mounting means, means for keying the
second side plate to the mounting means, and means securing
the first and second side plates in keyed relationship to the
mounting means.

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Docket M-391-C-l

14. A print head as defined in any one of claims 11,
12 or 13, wherein the mounting means is molded from moldable
plastics material.
15. A print head as defined in any one of claims 11,
12 or 13, wherein the mounting means and the supporting means
are molded in one piece of moldable plastics material.
16. A print head as defined in any one of claims
11, 12 or 13, wherein the mounting means is molded of moldable
plastics material.
17. A print head as defined in claim 11, wherein the
connecting means includes threaded fasteners.
18. A print head assembly, comprising: at least two
identical subassemblies, each subassembly having a one-piece
mounting block having a concave mounting surface and a support
disposed opposite the concave mounting surface and composed of
moldable plastics material, a series of drive wheels rotatably
mounted at the outer peripheries on the concave mounting
surface, a selector, the drive wheels having aligned holes
for receiving the selector, a series of printing elements
each having a plurality of different printing elements, the
printing bands being trained about the respective drive
wheels and the support, the support supporting a printing
element in a flat plane which is inclined from the perpendicular
relative to a reference line passing through the center of a
drive wheel and the support, and means for holding the
subassemblies so that both subassemblies are equally and
oppositely inclined with respect to a centerline extending
between the subassemblies and intersecting the of the
supports at a right angle and so that the printing elements
at the printing portion are in the same plane.
19. Apparatus as defined in claim 18, wherein the
subassemblies are asymetrical and cooperable with at least one
of the side plates to enable the subassemblies to be assembled
only with their respective supports disposed in the same
plane.
20. Apparatus as defined in claim 18, including
means for preventing the subassemblies from being assembled
with their respective supports out of the plane.


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Docket M-391-C-l

21. A print head assembly, comprising: at least
two identical subassemblies, each subassembly having a one-
piece mounting block having a concave mounting surface and a
support disposed opposite the concave mounting surface and
composed of moldable plastics material, a series of drive
wheels rotatably mounted at the outer peripheries on the
concave mounting surface, a selector, the drive wheels having
aligned holes for receiving the selector, a series of printing
elements each having a plurality of different printing elements,
the printing bands being trained about the respective drive
wheels and the support, the support supporting a printing
element in a flat plane which is inclined from the perpendicular
relative to a reference line passing through the center of a
drive wheel and the support, and means for holding the
subassemblies so that both supports are disposed close
together in the same plane and the reference lines are
inclined with respect to each other.
22. Apparatus as defined in claim 20, wherein the
subassemblies are asymmetrical and cooperable with one of the
side plates to enable the subassemblies to be assembled only
with their respective supports disposed in the same plane.
23. Apparatus as defined in claim 21, including
means for preventing the subassemblies from being assembled
with their respective supports out of the plane.
24. Method of making a print head assembly,
comprising the steps of: providing a pair of separate,
molded mounting blocks composed of plastics material each
having a substantially constant profile with an elongate
concave mounting surface, there being means opposite the
concave mounting surface for supporting printing bands,
providing for each of the mounting blocks a series of drive
wheels having central holes defining a continuous opening,
providing a series of printing bands for each mounting block
with each band having a plurality of different printing
elements, providing a pair of band selectors, providing a
pair of separate first and second molded side plates composed
of plastics material with the second side plate having
openings, assembling a series of drive wheels and a series of
printing bands on each of the mounting blocks with the drive


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Docket M-391-C-1

wheels rotatably supported on the concave mounting surface
with the printing bands trained about the respective drive
wheels and the band supporting means, providing a locator
and a cooperating locator-receiving recess for the first side
plate and for one side portion of each mounting block,
locating the pair of mounting blocks in side-by-side, oriented
relationship with respect to each other and with respect to
the first side plate using the respective cooperating locators
and locator-receiving recesses to present the printing
elements at the band supporting means in a common plane,
providing a locator and a cooperating locator-receiving
recess for the second side plate and for the other side
portion of each mounting block, each band selector being
positioned in the continuous opening of the respective
series of drive wheels with a portion of the band selector
projecting through the respective opening in the second side
plate, and locating the second side plate with respect to
the pair of mounting blocks using the respective cooperating
locators and locator-receiving recesses.
25. Method of making a print head assembly,
comprising the steps of: providing a pair of separate and
identical molded mounting blocks composed of plastics material
with each mounting block having means providing a concave
mounting surface, there being means opposite the concave
surface providing a band support, providing for each of the
mounting blocks a series of drive wheels having central holes
defining a continuous opening, providing a series of printing
bands for each mounting block with each band having a plurality
of different printing elements, providing a pair of band
selectors providing a pair of first and second molded side
plates composed of plastics material with the second side
plate having openings, assembling a series of drive wheels
and a series of printing bands on each of the mounting
blocks with the drive wheels rotatably supported by the
support surface and with the printing bands trained about
the respective drive wheels and band support means, providing
the mounting blocks and at least one side plate with cooperating
means enabling the mounting blocks to be positioned in only

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Docket M-391-C-l

opposite orientations with respect to each other, positioning
the mounting blocks in opposite orientations with a centerline
through one series of wheels and its respective band support
means and another centerline through the other series of
wheels and the other band support means being equally and
oppositely angularly inclined with respect to a common
intervening line perpendicular to a plane provided by the
band support means with each band selector being positioned
in the continuous opening of the respective series of drive
wheels with a portion of the band selector projecting through
the respective opening in the second side plate and with the
first and second side plates secured to both mounting blocks
for maintaining the positioned relationship of the mounting
blocks and the first and second side plates relative to each
other.
26. Method of making a print head assembly,
comprising the steps of: providing a pair of mounting means
each having a concave mounting surface, there being band
supporting means disposed opposite each concave mounting
surface, providing for each mounting means a series of drive
wheels having holes, providing for each mounting means a
series of printing bands each having a plurality of different
printing elements, providing a pair of selectors, providing
a pair of first and second side plates with the second side
plate having openings, placing the pair of mounting means and
supporting means in a fixture, assembling the drive wheels and
the respective printing bands onto the mounting means so that
the drive wheels are rotatably supported on the concave
mounting surface with their holes in general alignment
and with the printing bands being trained about the
respective drive wheels and the supporting means to provide
a pair of subassemblies, removing the subassemblies from
the fixture, and connecting the first and second side
plates to opposite sides of the subassembly in a predetermined
orientation with the selectors extending through the openings
in the second side plate and into the holes to engage any
selected wheel to provide an assembly.

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Docket M-391-C-1

27. Method of making a print head assembly, comprising
the steps of: providing a pair of separate and identical
molded mounting blocks composed of plastics material with
each mounting block having means providing a concave mounting
surface, there being means opposite the mounting surface
providing a band support, providing for each of the mounting
blocks a series of drive wheels having central holes defining
a continuous opening, providing a series of printing bands
for each mounting block with each band having a plurality of
different printing elements, providing a pair of band
selectors, providing a pair of first and second molded side
plates composed of plastics material with the second side
plate having openings, assembling a series of drive wheels
and a series of printing bands on each of the mounting
blocks with the drive wheels rotatably supported on the
mounting surface and with the printing bands trained about
the respective drive wheels and band support means,
positioning the mounting blocks in opposite orientations
with a centerline through one series of wheels and its
respective band support means and another centerline
through the other series of wheels and its respective band
support means being equally and oppositely angularly
inclined with respect to a common intervening line perpendicular
to a plane provided by the band support means, wherein the
positioning step includes providing a locator and a
cooperating locator-receiving recess for the first side
plate and for one side portion of each mounting block,
locating the pair of mounting blocks in side-by-side,
oriented relationship with respect to each other and with
respect to the first side plate using the cooperating
locator and locator-receiving recesses to present the
printing elements at the band supporting means in a common
plane, and providing a locator and a cooperating locator-receiving
recess for the second side plate and for the other side
portion of at least one of the mounting blocks, locating
the second side plate with respect to the mounting blocks,
and securing the first and second side plates to the
mounting blocks with the mounting blocks disposed in

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Docket M-391-C-l

side-by-side oppositely oriented relationship with respect
to each other with each band selector being positioned in
the continuous opening of the respective series of drive
wheels with a portion of the band selector projecting
through the respective opening in the second side plate.
28. Method of making a print head assembly,
comprising the steps of: providing a pair of separate
molded mounting blocks composed of plastics material with
each mounting block having means providing a concave support
surface, there being means opposite the mounting surface
providing a band support, providing for each of the mounting
blocks a series of drive wheels having central holes defining
a continuous opening, providing a series of printing bands for
each mounting block with each band having a plurality of
plates composed of plastics material with the first side
plate being devoid of structure that would interfere with
the connection of the mounting blocks to the first side
plate and with the second side plate having openings, assembling
a series of drive wheels and a series of printing bands on
each of the mounting blocks with the drive wheels rotatably
supported on the mounting surface and with the printing
bands trained about the respective drive wheels and band
support means, and positioning the mounting blocks in
opposite orientations with a centerline through one series
of wheels and its respective band support means and another
centerline through the other series of wheels and its
respective band support means being equally and opposite
angularly inclined with respect to a common intervening line
perpendicular to a plane provided by the band support means,
wherein the positioning step includes providing a locator
and a cooperating locator-receiving recess for the first
side plate and for one side portion of each mounting block,
locating the pair of mounting blocks in side-by-side,
oriented relationship with respect to each other and with
respect to the first side plate using the cooperating
locator and locator-receiving recesses to present the
printing elements at the band supporting means in a common
plane, and providing a locator and a cooperating locator-


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Docket M-391-C-1

receiving recess for the second side plate and for the other
side portion of at least one of the mounting blocks, and
locating the second side plate with respect to the mounting
blocks.
29. Method of making a print head assembly,
comprising the steps of: providing a pair of separate,
molded mounting blocks composed of plastics material each
having means providing an elongate concave mounting surface,
there being means opposite the mounting surface for supporting
printing bands, providing for each of the mounting blocks a
series of drive wheels having central holes defining a
continuous opening, providing a series of printing bands for
each mounting block with each band having a plurality of
different printing elements, providing a pair of band selectors,
providing a pair of first and second molded side plates
composed of plastics material with the second side plate
having openings, assembling a series of drive wheels and a
series of printing bands on each of the mounting blocks with
the drive wheels rotatably supported on the concave mounting
surface with the printing bands trained about the respective
drive wheels and the band supporting means to provide a pair
of subassemblies, thereafter locating the pair of subassemblies
in side-by-side, oriented relationship with respect to each
other and with respect to the first side plate using locators
and cooperating locator-receiving recesses, with each band
selector being positioned in the continuous opening of the
respective series of drive wheels with a portion of the band
selector projecting through the respective opening in the
second side plate, and thereafter locating the second side
plate with respect to the pair of mounting blocks to
provide an assembly.
30. Method of making a print head assembly,
comprising the steps of: providing a pair of separate,
molded mounting blocks from plastics material each having
means providing an elongate concave mounting surface, there
being means opposite the mounting surface for supporting a
printing band, providing for each of the mounting blocks a
series of drive wheels having central holes defining a

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Docket M-391-C-l

continuous opening, providing a series of printing bands for
each mounting block with each band having a plurality of
different printing elements, providing a pair of band
selectors, providing a pair of first and second molded
side plates composed of plastics material with the second
side plate having openings, assembling a series of drive
wheels and a series of printing bands on each of the mounting
blocks with the drive wheels rotatably supported on the
mounting surface with the printing bands trained about the
respective drive wheels and the band supporting means to
provide a pair of subassemblies, wherein the steps of
providing the molded mounting blocks and the first and
second molded side plates include providing cooperating
first locator means for the first side plate and for one
side portion of each mounting block and second locator
means for the second side plate and for the other side
portion of each mounting block, locating the pair of
subassemblies in side-by-side, oriented relationship
with respect to each other and with respect to the first side
plate using the first locator means, with each band selector
being positioned in the continuous opening of the respective
series of drive wheels with a portion of the band selector
projecting through the respective opening in the second side
plate, and thereafter locating the second side plate with
respect to the pair of mounting blocks using the second
locator means.
31. A print head assembly, comprising: a pair of
separate and identical mounting blocks composed of plastics
material with each mounting block having means providing a
concave mounting surface, means opposite the concave surface
providing a band support, a series of drive wheels for each
mounting block, the drive wheels of each series having central
holes defining a continuous opening, a series of printing bands
for each mounting block with each band having a plurality of
different printing elements, a pair of band selectors, a pair
of first and second side plates composed of plastics material
with the second side plate having openings, a series of the
drive wheels and a series of the printing bands being assembled


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Docket M-391-C-l
on each of the mounting blocks with the drive wheels rotatably
supported by the support surface and with the printing bands
trained about the respective drive wheels and band support
means, the mounting blocks and at least one side plate having
cooperating means enabling the mounting blocks to be positioned
in only opposite orientations with respect to each other, the
mounting blocks being positioned in opposite orientations with
a centerline through one series of wheels and its respective
band support means and another centerline through the other
series of wheels and the other band support means being equally
and oppositely angularly inclined with respect to a common
intervening line perpendicular to a plane provided by the band
support means with each band selector being positioned in the
continuous opening of the respective series of drive wheels with
a portion of the band selector projecting through the respective
opening in the second side plate and with the first and second
side plates secured to both mounting blocks for maintaining the
positioned relationship of the mounting blocks and the first
and second side plates relative to each other.
32. A print head assembly, comprising: a pair of
separate and identical mounting blocks composed of plastics
material with each mounting block having means providing a
concave mounting surface, means opposite the mounting surface
providing a band support, a series of drive wheels for each
mounting block, the drive wheels of each series having central
holes defining a continuous opening, a series of printing bands
for each mounting block with each band having a plurality
of different printing elements, a pair of band selectors, a
pair of first and second side plates composed of plastics
material with the second side plate having openings, a
series of the drive wheels and a series of the printing bands
being assembled on each of the mounting blocks with the drive
wheels rotatably supported on the mounting surface and with
the printing bands trained about the respective drive wheels
and band support means, the mounting blocks being positioned in
opposite orientations with a centerline through one series of
wheels and its respective band support means and another
centerline through the other series of wheels and its respective
band support means being equally and oppositely angularly
inclined with respect to a common intervening line perpendicular

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Docket M-391-C-l

to a plane provided by the band support means, a locator and a
cooperating locator-receiving recess for the first side plate
and for one side portion of each mounting block for locating
the pair of mounting blocks in side-by-side, oriented relation-
ship with respect to each other and with respect to the first
side plate to cause the printing elements to be presented at
the band supporting means in a common plane, a locator and a
cooperating locator-receiving recess for the second side plate
and for the other side portion of at least one of the mounting
blocks for locating the second side plate with respect to the
mounting blocks, and means for securing the first and second
side plates to the mounting blocks with the mounting blocks
disposed in side-by-side oppositely oriented relationship
with respect to each other, with each band selector being
positioned in the continuous opening of the respective series
of drive wheels and with a portion of the band selector
projecting through the respective opening in the second side
plate.
33. A print head assembly, comprising a pair of
separate mounting blocks composed of plastics material with each
mounting block having means providing a concave support surface,
means opposite each mounting surface providing a band support,
a series of drive wheels for each mounting block, the drive
wheels of each series having central holes defining a
continuous opening, a series of printing bands for each mounting
block with each band having a plurality of different printing
elements, a pair of band selectors, a pair of first and second
side plates composed from plastics material and with the second
side plate having openings, a series of the drive wheels and a
series of the printing bands being assembled on each of the
mounting blocks with the drive wheels rotatably supported on
the mounting surface and with the printing bands trained about
the respective drive wheels and band support means, the
mounting blocks being positioned in opposite orientations with
a centerline through one series of wheels and its respective band
support means and another centerline through the other series of
wheels and its respective band support means being equally and
opposite angularly inclined with respect to a common intervening

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Docket M-391-C-l

line perpendicular to a plane provided by the band support means,
a locator and a cooperating locator-receiving recess for the
first side plate and for one side portion of each mounting block
for locating the pair of mounting blocks in side-by-side, oriented
relationship with respect to each other and with respect to the
first side plate to cause the printing elements to be presented
at the band supporting means in a common plane, and a locator
and a cooperating locator-receiving recess for the second side
plate and for the other side portion of at least one of the
mounting blocks.
34. A print head assembly, comprising: a pair of
separate mounting blocks composed of plastics material each
having means providing an elongate concave mounting surface,
means opposite the mounting surface for supporting a printing
band, a series of drive wheels for each mounting block, the
drive wheels of each series having central holes defining a
continuous opening, a series of printing bands for each mounting
block with each band having a plurality of different printing
elements, providing a pair of band selectors, a pair of first
and second side plates composed of plastics material with the
second side plate having openings, a series of the drive wheels
being rotatably supported on the mounting surface with the
printing bands trained about the respective drive wheels and the
band supporting means to provide a pair of subassemblies, first
locating means for the first side plate and for one side portion
of each mounting block for locating the subassemblies in side-by-
side, oriented relationship with respect to each other and with
respect to the first side plate, second locating means for
the second side plate and for the other side portion of each
mounting block for locating the second side plate with respect
to the pair of mounting blocks, each band selector being
positioned in the continuous opening of the respective series
of drive wheels with a portion of the band selector projecting
through the respective opening in the second side plate.

-25-

Description

~ 162787




Docket M-391

PRINT HEAD ASSEMBLY AND ~IET~OD OF l`~AKING SA~lE
__ _ _
Background of the Invention
Field of the Invention
This invention relates to a method of making print
head assemblies and to print head assemblies.
Brief Description of the Prior Art
Various embodiments of a prior art print head as-
sembly are disclosed in U. S. Patent No. 3,968,7~5 to Paul ~.
Hamisch, Jr. granted July 13, 1976. One embodiment has a
lo single mounting block with a concave mounting surface for
mounting drive wheels and support means. Printing bands are
trained about the drive wheels and the support means. The
mounting block is formed integrally with the support means
and one side plate. There is a second side plate connected
to the mounting block and a selector for engaging any drive
wheel in its central hole to advance any selected printing
band. The selector extends through an opening in the second
side plate. The selector is assembled onto the side plate
before the second side plate is connected to the mounting
2~ block. In another embodiment suited for multi-line printing
there are two such mounting blocks, two series of drive
wheels and two series of printing bands and an integral
side plate. There is a second side plate connected to the
mounting blocks and there is a selector for each series of
wheels. The print head assembly is assembled similarly to
the manner described with respect to the previously mentioned
embodiment .

~ ~2~8~
~ocket M-391 2

1 In applicant's prior art print head assemblv accordin~
to U. S. Patent No. 3,968r745, on~ of the side plates is molded
integrally with the mounting block and the parting line
is taken along that side plate. This requires the mold for
the mounting block and the integral support means to be pro-
vided with a certain draft angle from side-to-side to
enable the resultant molded structure to be removed from
the mold. Moreover, the molding of the side plate integrally
with the mounting block an~ support means has at times
10 caused the resultant structure to be warped.
The goal of high quality printing may not be achieved
when the print head components are warped or when molding
draft is other than negligibleO Iligh quality printing is
required when printing machine readable codes such as the
OCR code or various types of bar codes.
U. S. Patent No. 3,796,152 to Eugene ~. Finke and
Paul H. ~Iamisch, Jr. granted March 12, 1974 discloses a print
head assembly having a mounting block with side plates. The
side plates mount the shaft which in turn mounts the multi-
20 sided side-by-side wheels.
Summary of the Invention
The invention relates to a low cost, compact, modular,
print head assembly having relatively few components, which
components are readily accurately molded using moldable
plastics material, and the molded components are easy to
assemble.
In molding the mounting block of the present
invention, the parting line is preferably midway between
the sides so the draft angle is about one half as large as
30 the draft angle for the mounting block in Patent No. 3,96~,7~5.
Moreover, by molding the mounting block separate from the
side plates, the mounting block is less likely to be warped.
This is due mainly to the fact that the mounting bloc~ according

~ 162'787
ocket M-391 3

1 to tle present invention can be made of relatively unifor~
section without abrupt changes in section.
It is one feature of the invention to make the
print head assembly by first assembling one or more sub-
assemblies, each subassembly including a printing block
having a concave mounting surface, drive wheels mounted
at their outer peripheries on the concave mounting surface,
supporting means, and printing bands trained about the drive
wheels and the supporting means. The invention utilizes
10 drive wheels having holes into which the selector extends.
The wheels are preferably small so that the size of the
print head can be small. It is preferred that the subas-
sembly or subassemblies which form part of the print head
assembly be assembled while the mounting block and support means
are on a fixture. Thereafter the side plates and the selector
assembled onto the subassembly or subassemblies. An important
feature is that the subassembly be a modular unit which is
easy-to-assemble and is easy-to-handle as a subassembly. It
is preferred to have the supporting means integrally molded
20 with the concave surface.
In making a print head assembly for printing two
or more lines of data, it is preferred to have the lines
close together without duplicating the number of parts. For
example, a two-line print head assembly according to the inven-
tion can be made by orienting one print head subassembly in
one way and orienting another identical print head subassembly
the oth~r way. This can be accomplished by having the
supporting means of each subassembly close together and
positioning the subassemblies at an angle with respect to
30 each other while the supporting means support the lines of
printing elements in a common plane. A line passing through
the axis of the drive wheels and center of the supporting means
intersects the plane at an angle with respect to the perpendicu-
lar. ~ach subassembly is inclined at the same angle with
respect to a centerline perpendicular to the supporting
plane, considering that the centerline passes between the sub-
assemblies.

~ 162'~7
)ocket M-391 4

1 Brief Des~ ption of the Drawin~s
FIGURE 1 is a partially exploded perspective view
of a print head assembly in accordance wi~h the invention;
FIGURE 2 is an snd view showing two subassemblies
and a side plate;
FIGURE 3 is a ~ectional view taken along line 3--3
of FIGU~E 2;
FIGURE 4 i5 a sectional view taken along line 4--4
of FIGURE 2;
FIGURE 5 is a fragmentary diagrammatic view showing
how the subassemblies are oriented;
FIGURE 6 is an exploded perspective view showing
how subassemblies can be assembled using a fixture; and
FIGURE 7 is a fragmen~ary perspective view of a
suba~sembly assembled on the fixture.
Detailed Description of the Pre~erred Embodiment
With reference initially to FIGURE 1, there is
disclosed, in partially exploded form, a print head assembly
generally indicated at 10. The assembly 10 is shown to
20 include two subassemblies 11 and 12, ~ide plates 13 and 14
and shiftable and rotatable selectors 15 and 16.
Referring now also to FIGURES 2 through 4, the
subassemblies 11 and 12 are shown to be identical, and hence
the same reference characters will be used to denote like
components. The subassemblies 11 and 12 have flexible printing
bands 17 arranged to print a plurality of lines. Each sub-
assembly includes a series of printing bands arranged to print
a single line. Each printing band has a printing portion 17
and a human readable portion 17~. Each prin~ing band 17 i8
30 engaged ~ith a drive wheel 18 which is rotatably mounted or
supported at its outer p~riphery on an arcuate concave mounting
surface 19. The concave mounting ~urfa~e 19 cradle~ the
respective series of wheels 18. The mounting ~urface 19 is
illustrated to be part of a mounting block 20. ~t is preferred
that a support 21 be formed integrally as part of the mounting
block as oppo~ed to having separate idler wheel~ which are well
known in the art so that manufacturing costs can be kept to a
minimum. The printing band~ 17 o~ each subassembly are trained

~ 162787
~ocket M-391 5

1 about the respective wheels 18 and the support 21 and are under
a slight amount of tension to insure good traction between lugs
22 on the underside of the printing band and lugs 23 at the
outer peripheries of the wheels 18. The outer surfaces of the
printing bands ~7 are provided with a series of different printing
elements 24 along the printing portion 17' for printing selectcd
indicia on a record. As best sho~n in FIGURE 5, the supports
21 each support a plurality of printing elernents 24 at a
printing zone Z in a common flat plane P. The subassemblies 11
and 12 are shown to be disposed at predetermined angles so that
the printing elements 24 are in fact in the common plane r and
yet the subassemblies 11 and 12 are identical. This is
accomplished by having the subassemblies 11 and 12 in reverse
positions as best illustrated in FIGUR~S 3 and 4. It is
readily apparent from these FIGURES that the integral mounting
blocks 20 and their respective supports 21 are integral asym-
metrical parts. The side plate 14 has a pair of projections or
lugs 25 and 26 which are received in cavities 27 and 2S. The
projections 25 and 26 are offset from each other so that the
20 subassembly 12 can be connected to the side plates 13 and 14 in
only one position as is evident from FIGUR~ 3 and the sub-
assembly 11 can be connected to the side plates 13 and 14 only
in the opposite position as indicated in FIGUX~ 4.
The side plate 14 has a plurality of rectangular
sockets or recesses 29 for receiving respective keys or locators
30. The side plate 13 also has a plurality of sockets or
recesses 29 for receiving keys or locators 30. The recesses
29 and keys 30 fit precisely and accurately locate the side
plate with respect to the integral mounting ~lock 20 and the
30 support 21 of each subassembly. Threaded fasteners 31 pass
through holes 32 in the respective side plates 13 and 14 and
are threadably received in holes 33 in the mounting block 20
to hold the subassemblies 11 and 12 and the side plates 13 and
14 accurately in assembled relationship.

l 1627B7
Docket M-3~1 6

1 The selectors 15 and 16 have respective knobs 34
and 35 and respective selector shafts 36 and 37. Each selector
shaft (only shaft 36 being shown in detail) has a plurality
of lugs 38 ~or engaging in respective recesses 18' at the
inner periphery of respective wheels 18. Further details of
the selector are best shown in U. S. Patent No. 3,968,745.
Each selector 15 and 16 also includes a detent element 39
also best shown in U. 5. Patent No. 3,968,745. The detent element
39 releasably holds the respec~ive selector in any selec~ed
lo position. Selectors 15 and 16 further include respective indicators
40 and 41 which are mounted for sliding movement by guides 42
and 43, and 44 and 450 The indica~ors 40 and 41 have pointers
40' are aligned with the lugs 38 to indicate the wheel 18 which
is being engaged. Each selector 15 and 16 is provided with a
respective re~ainer 47 and 48 for holding the selectors 15 and
16 assembled with the side plate 13.
With reference to FIGURE 6, there is shown a fixture
generally indicated at 50. It is apparent that the fixture 50
is similar to the structure of the side plate 14 except that
20 the sockets 29 and the spacers 49 associated with each sub-
assembly are spaced relatively widely apart. This wide
spacing as shown in FIGURE 6 facilitates assembly of the wheels
18 and printing bands 17 onto the unting block 20 and the
support 21 because there is adequate working space around each
mounting block 20 and its support 21. The mounting blocks 20
are plugged into the fixture 50 as indicated. Thereafter,
each wheel and its respective printing band 17 is moun~ed onto
the respective mounting block. This is accomplished by placing
the gear in mesh with several lugs 22, thereafter positioning
30 one of the printing blocks at the printing zone Z as shown in
FIGURE 7 and thereafter manually tensioning the print band
and sliding the wheel onto the concave mounting surface 19.
The printing band 17 and its respective wheel 18 are manually
pushed along until the printing bands and wheels are stacked
in a series, a partial series being ~hown in FIGURE 7. With
the arrangement shown in FIGURES 6 and 7, the subassemblies
11 and 12 and the subassemblies 11 and 12 can be stacked or

~ ~62'7~7
~ocket Mo391 7

1 conveniently stored until ready to be ~ssembled with the
remaining componentæ o~ the print head assembly. The con~truc
tion o~ the subassemblies 11 and 12 ls economically accom-
plished because the m~unting blocks and the supports 21 are
integral. Both suba~semblies 11 and 12 are easy to
handle and therefore with respect to this feature it is not
necessary that the mounting blook 20 and the support 21 be
integral. With respect to this fea~ure it is only necessary
that once the wheels 18 and bands 17 have been assembled
lo onto the mounting block 20 and the support 21 that the resultant
unit be of a subassembly which can be easily handled to
facilitate final assembly, and the subassemblies form Lmportant
parts of the print head assembly. In the prior art
device according to United States Patent No. 3,796,152, where
wheels are used, there is no easy-to-handle subassembly
because the shaft for the idler wheels is not supported ~r
mounted by the subassembly itself but rather by side plates.
It is another feature of the invention to provide
means that render it impossible to assemble the modular sub-
20 assemblies 11 and 12 incorrectly because the rectangulax keys30 have sides 30' that extend parallel to a centerline C and if
the positions of the subassemblies 11 and 12 were interchanged,
it would be readily apparent to the assembler that the supports
21 would be too far apartO As indicated in FIGURES 2 and 5,
the supports are close together so that the lines of printing
on the record will be close. Also, the projections 25 and 26
make misorienta~ion of the suba~semblies 11 and 12 impossible.
As is evident, the axes of the two series of wheels 18
are more widely spaced apart than the supports 21. As illus-
30 trated, a reference line RF drawn through the axis of thewheels 18 and the center of the support 21 of subassembly 11
exists at an angle A with respect to the centerline C.
Similarly, a reference line RF' drawn through the axis of the
wheels 18 and the center of the support 21 of subassembiy 12
makes an angle A' with the centerline C. The centerline C is
perpendicular to the plane P and is disposed between the
respective subassemblies 11 and 12. The angles A and A' are
equal to each other so it is readily apparent tha~ is it only

27~7
,cket M-391 8

1 necessary to reverse the positions of the subassemblies 11
and 12 in order to be able to assemble the subassemblies 11
and 12 properly wi~h respect to the side plates 13 and 14.
In assembling the print head assembly 10, it is
preferred to key the subassemblies 11 and 12 to the side
plate 14 by means of the locators 30 extending into sockets
29 and thereupon pass the threaded fasteners 31 through holes
32 and into the mounting blocks 20. It is apparent that the
side plate 14 is devoid of posts which would interfere with
10 the connection of the subassemblies 11 and 12 and the sicle
plate 14. Thereupon the selector shafts 36 and 37 are insertec'
through openings 51 in the side plate 13 and then retainers
47 and 4~ are connected to the respective shafts 36 and 37 to
hold the selectors 15 and 16 in assembled relationship with
respect to side plate 13. The indicators 40 and 41 are
inserted into guided relationship with respect to respective
guides 4Z and 43, and 44 and 45. The guides 42 through A5 are
part of posts 52, 53 and 54 and there are additional posts 55
(only a fragment of which is shown) and 56. The posts 52 through
20 56 have respective keys or locators 57 received in respective
sockets or holes 58. Once the selectors 15 and 16 have been
assembled onto the side plate 13, the outer portion of the
selector shafts 36 and 37 are inserted into the holes 18' in
the wheels 18 and the locators 57 are inserted into the sockets
58. Thereupon the threaded fasteners 31 associated ~lith the
side plates 13 and 14 can be passed through respective holes 32
and into the mounting blocks 20.
Other embodiments and modifications of this invention
will suggest themselves to those skilled in the art, and all
30such of these as come within the spirit of this invention are
included within its scope as best defined by the appended
claims.