EP0475613A1 - Mécanisme de tracteur avec entraînement par roues à picots - Google Patents

Mécanisme de tracteur avec entraînement par roues à picots Download PDF

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Publication number
EP0475613A1
EP0475613A1 EP91307701A EP91307701A EP0475613A1 EP 0475613 A1 EP0475613 A1 EP 0475613A1 EP 91307701 A EP91307701 A EP 91307701A EP 91307701 A EP91307701 A EP 91307701A EP 0475613 A1 EP0475613 A1 EP 0475613A1
Authority
EP
European Patent Office
Prior art keywords
drive
shaft
drive shaft
wheel
pins
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91307701A
Other languages
German (de)
English (en)
Inventor
Kenneth R. Williams
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HP Inc
Original Assignee
Hewlett Packard Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hewlett Packard Co filed Critical Hewlett Packard Co
Publication of EP0475613A1 publication Critical patent/EP0475613A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J11/00—Devices or arrangements  of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
    • B41J11/26—Pin feeds
    • B41J11/28—Pin wheels

Definitions

  • This invention relates to a drive tractor mechanism for moving sheets of paper through printers.
  • printers utilize continuous sheets of paper as a printing medium.
  • One type of paper commonly known as “computer paper” has a narrow, detachable margin along each side. Holes are formed in the margins at evenly spaced intervals. Lateral perforations in the computer paper define the top and bottom edges of individual sheets.
  • Each marginal hole on one side of the computer paper has a laterally aligned counterpart on the other side. Accordingly, each marginal hole and its counterpart are spaced the same distance from the top and bottom edges of a sheet of computer paper.
  • the printer has a drive tractor mechanism for moving the paper through the printer.
  • a typical tractor mechanism includes two drive wheels connected by a rotatable drive shaft.
  • the drive wheels include a number of radially protruding drive pins. Each pin is shaped to fit through a marginal hole in the paper.
  • the drive wheels are located on the drive shaft so that the drive pins of one wheel engage the marginal holes on one side of the computer paper, and the drive pins on the other wheel engage the marginal holes on the other side of the paper. The drive pins force the paper through the printer as the drive shaft and connected drive wheels rotate.
  • the drive tractor mechanism To ensure that the paper is properly driven by the pins of both drive wheels, the drive tractor mechanism must be assembled so that each drive pin on one drive wheel is laterally aligned with a drive pin on the other drive wheel. When so assembled, each laterally aligned pair of pins will engage a laterally aligned pair of marginal holes in the paper, and the paper will move in a straight path through the printer.
  • the tractor mechanism drive wheels have central openings that are shaped in cross-section to match the cross-sectional shape of the drive shaft that is inserted through the wheel.
  • the drive shaft hence the drive wheel openings, are square in cross section.
  • the number of drive pins (typically, five) carried on the drive wheel did not correspond to the number of sides (for example, four) of the drive shaft. Consequently, the drive tractor mechanism could be assembled ( i.e. , the drive wheels mounted to the drive shaft) so that the drive pins on one drive wheel were laterally misaligned with respect to the drive pins on the other drive wheel. Laterally misaligned pins will riot properly engage the marginal holes in the paper.
  • the support shaft extends parallel to the drive shaft and through carriages that carry the drive wheels.
  • the support shaft keeps the carriages from twisting relative to the axis of the drive shaft.
  • the support shaft therefore, stabilizes the position of the drive wheels relative to the computer paper so that the drive pins will remain in engagement with the marginal holes as the paper is driven through the printer.
  • the inclusion of a support shaft to stabilize the drive tractor mechanism adds complexity and cost to the manufacture and assembly of a printer.
  • This invention is directed to a drive tractor mechanism that eliminates the possibility of assembling a the mechanism with drive pins laterally misaligned.
  • the drive wheels and drive shaft are configured so that each drive pin on one drive wheel will laterally align with a drive pin on the other drive wheel so that laterally aligned pins engage laterally aligned marginal holes in the paper.
  • Another aspect of this invention relates to a drive tractor mechanism that is constructed to eliminate the need for a support shaft to stabilize the drive wheel carriages relative to the drive shaft.
  • the body or other portion of the printer housing, etc. includes a portion that is engaged by the drive wheel carriages. The close fit of the carriage and the portion of the printer body prevents excessive swinging or twisting movement of the carriage relative to the drive shaft.
  • FIG. 1 is a perspective exploded view of one embodiment of a preferred drive wheel and drive shaft configuration for a drive tractor mechanism formed in accordance with the present invention.
  • FIG. 2 is a perspective view of an alternative embodiment of the present invention showing a drive tractor mechanism mounted to the body of a printer so that the tractor mechanism is stabilized relative to the drive shaft.
  • FIG. 3 is a side view, in partial section, showing the drive tractor mechanism of Fig. 2.
  • FIG. 4 is a side view of another embodiment of a drive tractor mechanism that is mounted to the body of a printer.
  • Fig. 1 shows a drive shaft 10 and drive wheels 12 of a drive tractor mechanism formed in accordance with the present invention.
  • the drive wheels 12 illustrated in this embodiment each include five drive pins 14 that protrude radially outwardly from the circumferential edge 15 of the drive wheel 12.
  • the pins 14 are evenly spaced around the wheel edge 15.
  • Each drive wheel 12 also includes a central opening 16.
  • the opening 16 is shaped in cross-section to match the cross-sectional shape of the drive shaft 10, as described more fully below.
  • the drive tractor mechanism is assembled by mounting a drive wheel 12 over each end of the drive shaft 10.
  • the drive shaft 10 is sized to fit into the openings so that the drive wheels 12 may be slid along the length of the drive shaft 10.
  • the drive wheels 12 are moved to locations on the drive shaft 10 that correspond to the position of the holes that are present in the margins of computer paper (not shown).
  • At least one drive pin 14 on each wheel engages a hole in the margin of the computer paper.
  • each drive pin 14 on a wheel 12 is laterally aligned with the drive pin 14 on the other wheel 12.
  • Dashed line 18 in Fig. 1 is provided to illustrate two laterally aligned pins 14a, 14b that will properly engage a pair of laterally aligned marginal holes in the computer paper.
  • Line 18 is parallel to the longitudinal axis of the drive shaft 10. It can be appreciated that all of the drive pins 14 on one wheel in Fig. 1 have a laterally-aligned counterpart pin on the other wheel.
  • the drive wheels 12 and shaft 10 are configured so that the wheels and shaft may be assembled no other way than with each pin 14 in one wheel in lateral alignment with a pin 14 on the other wheel.
  • the number of drive pins 14 on each drive wheel 12 is equal to the number of sides 24 on the drive shaft 10 and to the number of faces 22 of the central opening 16 formed in each drive wheel 12.
  • the drive wheels 12 are identical with respect to the position of the pins 14 relative to the opening 16. For instance, the embodiment illustrated in Fig. 1 shows each pin 14 as radially aligned with one of the five apices of the pentagonal-shaped opening 16. Consequently, the pins 14 on one drive wheel 12 will be laterally aligned with those of the other drive wheel, irrespective of how either wheel is oriented before being slid onto the shaft 10.
  • lateral alignment of the pins 14 of each wheel 12 will be assured where the tractor mechanism is configured so that the number of sides 24 of the drive shaft is equal to an integer multiple of the number of the evenly-spaced drive pins 14 on the drive wheels 12, or, conversely, where the number of drive pins 14 is an integer multiple of the number of shaft sides 24.
  • the tractor mechanism is configured so that the number of sides 24 of the drive shaft is equal to an integer multiple of the number of the evenly-spaced drive pins 14 on the drive wheels 12, or, conversely, where the number of drive pins 14 is an integer multiple of the number of shaft sides 24.
  • the tractor mechanism is configured so that the number of sides 24 of the drive shaft is equal to an integer multiple of the number of the evenly-spaced drive pins 14 on the drive wheels 12, or, conversely, where the number of drive pins 14 is an integer multiple of the number of shaft sides 24.
  • lateral alignment of the pins 14 of two drive wheels will be assured after the wheels are mounted to a drive shaft, as long as the drive shaft 10 has
  • Fig. 2 shows another embodiment of a drive tractor mechanism 50 of the present invention mounted to the body 52 of a printer.
  • a pair of drive wheel carriages 54, 56 are provided to feed the computer paper through the printer.
  • Each carriage 54, 56 has a drive wheel 58 and a sheave 60 rotatably mounted between a pair of side walls 62, 64.
  • An endless drive belt 66 having outwardly protruding drive pins 68 encircles the drive wheel 58 and the sheave 60 of each carriage.
  • the carriages 54, 56 are mounted to slide over a drive shaft 70.
  • the drive shaft 70 fits through central openings in the drive wheels 58.
  • the drive shaft 70 is rotated by known mechanisms (not shown) to drive the belt 66.
  • the pins 68 which engage the marginal holes in the computer paper, move as the belt 66 is driven and, therefore, advance the computer paper relative to the printer.
  • each carriage 54, 56 is stabilized against twisting or swinging relative to the longitudinal axis of the drive shaft 70. Stabilization of each carriage 54, 56 is accomplished by connecting part of the carriage to a portion 72 of the printer body.
  • the portion 72 of the printer body to which the carriages 54, 56 connect comprises a rigid thin sheet of material, such as metal, that is bent at one end into a generally "C" shape, having a bottom part 74, a side part 76, and a top part 78.
  • the parts of the carriage side walls 62, 64 that extend outwardly from the sheave 60 are shaped to fit tightly within the space defined by the C-shaped bend in the printer body portion 72.
  • a notch 80 is formed in the upper edges of the side walls 62, 64. The notch 80 is shaped to receive therein the top part 78 of the printer body portion 72.
  • the fit between the printer body portion 72 and the side walls 62, 64 of the carriages is tight enough to prevent the carriages 54, 56 from rotating excessively about the drive shaft 70.
  • FIG. 4 A side view of another embodiment of the present drive tractor mechanism is shown in Fig. 4.
  • the drive wheel carriages 90 (only one of which is shown in Fig. 4) are constructed in a manner substantially identical to those 54, 56 described with respect to Figs. 2 and 3, except that the parts of the side walls 92 that engage the printer body (Fig. 4) are shaped unlike the side walls 62, 64 of the previous embodiment. More particularly, carriages 90 are configured to engage a flat, straight edge 96 of a printer body portion.
  • the side walls 92 of the carriages 90 include hooks 98 formed for slidably engaging the edge 96. Each hook 98 is sized so that the edge 96 fits tightly thereto to stabilize the carriage 90 relative to the drive shaft 100 that extends through the carriage 90.

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  • Advancing Webs (AREA)
EP91307701A 1990-09-11 1991-08-21 Mécanisme de tracteur avec entraînement par roues à picots Withdrawn EP0475613A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US58073790A 1990-09-11 1990-09-11
US580737 1990-09-11

Publications (1)

Publication Number Publication Date
EP0475613A1 true EP0475613A1 (fr) 1992-03-18

Family

ID=24322342

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91307701A Withdrawn EP0475613A1 (fr) 1990-09-11 1991-08-21 Mécanisme de tracteur avec entraînement par roues à picots

Country Status (2)

Country Link
EP (1) EP0475613A1 (fr)
JP (1) JPH04246051A (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0035215A1 (fr) * 1980-03-03 1981-09-09 Dataproducts Corporation Dispositif d'avance du papier avec un mouvement pas-à-pas très précis
DE3633459A1 (de) * 1985-10-02 1987-04-16 Canon Kk Stiftvorschubvorrichtung fuer aufzeichnungsanlagen

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0035215A1 (fr) * 1980-03-03 1981-09-09 Dataproducts Corporation Dispositif d'avance du papier avec un mouvement pas-à-pas très précis
DE3633459A1 (de) * 1985-10-02 1987-04-16 Canon Kk Stiftvorschubvorrichtung fuer aufzeichnungsanlagen

Also Published As

Publication number Publication date
JPH04246051A (ja) 1992-09-02

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