EP0144153B1 - Dot matrix printer - Google Patents

Dot matrix printer Download PDF

Info

Publication number
EP0144153B1
EP0144153B1 EP84307545A EP84307545A EP0144153B1 EP 0144153 B1 EP0144153 B1 EP 0144153B1 EP 84307545 A EP84307545 A EP 84307545A EP 84307545 A EP84307545 A EP 84307545A EP 0144153 B1 EP0144153 B1 EP 0144153B1
Authority
EP
European Patent Office
Prior art keywords
cam
pawl
wheel
profile
platen
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.)
Expired
Application number
EP84307545A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0144153A2 (en
EP0144153A3 (en
Inventor
Pierangelo Berruti
Giancarlo Cella
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.)
Telecom Italia SpA
Original Assignee
Ing C Olivetti and C SpA
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 Ing C Olivetti and C SpA filed Critical Ing C Olivetti and C SpA
Publication of EP0144153A2 publication Critical patent/EP0144153A2/en
Publication of EP0144153A3 publication Critical patent/EP0144153A3/en
Application granted granted Critical
Publication of EP0144153B1 publication Critical patent/EP0144153B1/en
Expired 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
    • B41J25/00—Actions or mechanisms not otherwise provided for
    • B41J25/001—Mechanisms for bodily moving print heads or carriages parallel to the paper surface
    • B41J25/006—Mechanisms for bodily moving print heads or carriages parallel to the paper surface for oscillating, e.g. page-width print heads provided with counter-balancing means or shock absorbers
    • 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
    • B41J19/00—Character- or line-spacing mechanisms
    • B41J19/76—Line-spacing mechanisms
    • B41J19/78—Positive-feed mechanisms
    • B41J19/80—Pawl-and-ratchet mechanisms
    • B41J19/82—Pawl-and-ratchet mechanisms moving a paper or like carriage
    • B41J19/84—Pawl-and-ratchet mechanisms moving a paper or like carriage in the form of a roller rotated for line spacing

Definitions

  • the present invention relates to a dot matrix printer comprising a printing head movable parallel to a writing platen for selectively printing dots on a writing medium disposed on the platen and a line-spacing device comprising a toothed wheel coupled to the platen and a pawl for intermittently rotating the wheel to advance the writing medium between two successive lines of printed dots.
  • a platen advancing device for intermittently advancing a record carrier comprises an operating arm with two cam followers cooperating with respective radial cam profiles.
  • At one end of the arm there is a gear segment selectively meshing with a gear connected to the platen.
  • the arm is supported by a stationary pivot engaged in a slot of the arm.
  • One cam pushes the arm to bring the gear segment into engagement with the platen gear by a radial displacement of the arm relative to the gear. Then the other cam rotates the arm about the supporting pivot to rotate the platen by an angular displacement.
  • the object of the present invention is to provide a dot matrix printer which is very compact, and silent, and has few moving parts and is such as to allow the paper to be advanced manually without the use of additional devices.
  • the dot matrix printer according to the invention meets this object and is characterised in the manner set forth in claim 1.
  • the printer includes a writing platen roller 10 fitted on a shaft 12 rotatable on a base 14.
  • a paper tape 16 is partly wound on the platen 10 and is advanced during writing operations by means of incremental rotations of the platen 10 onto which it is guided by a guide plate 18.
  • a slide 20 moves parallel to the axis of the platen 10 on a guide 22.
  • the slide comprises a flat support plate 24 on which a series-parallel thermal head 26 is fixed.
  • the printing head 26 is similar to that described in our Italian Patent No 1,000,641 and is formed by a small plate 29 of ceramic material, on which twenty resistive writing elements are laid aligned along a printing line parallel to the axis of the platen 10, for printing successions of dots on a thermosensitive layer of the paper 16.
  • the small plate 29 is glued at its central region 31 to the plate 24, while at the ends 32, 33 it is simply supported.
  • the small plate is slightly flexible and is kept pressed tangentially against the platen 10 by two elastic laminae 34, 36 fixed to the base 14 by tabs 35 and in sliding contact at one end 37 with two pads 38, 39 retained by forks 40 and 41 of the plate 24 and bearing against the small plate 29.
  • the slide 20 is moved by means of a peg 21 engaged with a groove 42 in the outer surface of a cylinder 44 having its axis parallel to the writing platen 10, and being rotated by a motor 45 through a reduction gear 43.
  • the groove 42 is formed by two helical arcs having constant slope but opposite directions, each extending for about 180° and being connected together with the points of reversal of the motion of the slide 20 corresponding. Consequently during a complete rotation of the cylinder 44, the slide 24 completes one forward pass and one return pass at constant velocity.
  • the thermal head 26 has a stroke which covers two characters which is equal to about 4 mm.
  • the cylinder 44 (Fig. 5) includes moreover a face cam 46 and a radial cam 48, which serve to produce the incremental rotation of the cylinder 10 to effect the basic line spacing between two successive lines of printed dots.
  • the face cam 46 and the radial cam 48 include a pair of lobes 47, 47' and 49, 49' respectively which are diametrically opposed and are interposed between zero lift regions.
  • a beam 50 (figs 1 and 2) having a cam follower arm 52 held against the radial cam 48 by a spring 53 can rotate and slide axially on the shaft 12 of the writing platen.
  • the beam 50 is provided with a peg 54 projecting in the direction parallel to the axis of rotation of the cylinder 44 and cooperating with the face cam 46 by virtue of the action of a helical spring 45 compressed between the beam 50 and a side 15 of the base.
  • the beam 50 is moreover provided with an appendage 56 projecting parallel to the shaft 12 and having a sector 58 which is toothed at the front and selectively engaged with corresponding face toothing 60 of a wheel 62 fitted on the shaft 12.
  • the cams 46, 48 are so phased relative to the groove 42 that during the constant velocity portions of the strokes of the slide 20, the face cam 46 keeps the beam 50 spaced from the wheel 62 by overcoming the action of the spring 45.
  • the cam 46 releases the peg 54 of the beam 50 thereby allowing engagement between the toothed portion 58 of the beam 50 and the toothed wheel 62.
  • a lobe 49 of the cam 48 (Fig. 2) rotates the beam 50 anticlockwise, and the beam in turn makes the writing platen 10 rotate through an arc corresponding to one basic line spacing of the paper 16.
  • the timing signals necessary for synchronising with the movement of the slide 20 the printing pulses coming through a cable 19 (Fig. 1) from a logic circuit not shown in the drawings are produced by a synchronisation device comprising a small plate 71 of insulating material (Figs. 2, 3) fixed to the side of the base 14 coaxially with the axis of rotation of the cylinder 64 and on which concentric conducting tracks 72, 73, 74 are deposited by a printed circuit technique.
  • the track 72 is formed by an open ring 72a from which a plurality of inwardly directed radial segments 72b branch off, while the track 73 is formed by an open ring 73a within the track 72, from which a plurality of outwardly directed radial segments 73b branch off.
  • the segments 72b and the segments 73b are regularly interdigitated.
  • the track 74 is formed by a ring which occupies the central part of the small plate 71 and constitutes the common return for the synchronisation circuit.
  • a metal lamina 78 is fixed which ends in two diametrically opposed resilient contacts 79, 80, of which the contact 79 slides alternately on the segments 72b, 73b, and the contact 80 slides on the ring 74. Consequently during the rotation of the cylinder 44 the contacts 79,80 short circuit the segments 72b, 73b and the ring 74 in order to generate the timing signals transmitted over a cable 83 to the control logic.
  • an additional radial segment 77 is disposed which is used to give a line start signal when the slide 20 is at one of the ends of the stroke.
  • the segments 72b, 73b are equidistantly spaced by an arc corresponding to a step between two successive printed dots on the medium 16.
  • the aforesaid arc is 11°15' and corresponds to a step of 0.26 mm between two dots.
  • the step between two printed dots can be varied in a very simple manner without modifying the mechanical structure of the printer and without altering the logic architecture of the circuit controlling the printing head.
  • the small plate 71 is interchangeable with others having a different spacing between the segments 72b, 73b.
  • the small plate 71 can be removed by unscrewing a nut 70 (Fig. 1) that holds it fixed to the side 15.
  • the diagram SC shows the profile of the groove 42, which is intended to move the head 26, as a function of the angle of rotation of the cylinder 44
  • the diagrams IN and SP relate to the profiles of cams 48 and 46 respectively provided for line spacing and axial displacement of the beam 50.
  • the separation of the beam 50 from the wheel 62 occurs in a portion DIS of the diagrams IN and SP in which the lift of the cam 48 is constant, while the clockwise rotation reloading the beam 50 occurs in the succeeding portion AV in which the lift of the cam 46 is a maximum, that is, the toothing 58 of the beam 50 is completely separated from the wheel 62.

Landscapes

  • Handling Of Sheets (AREA)
  • Character Spaces And Line Spaces In Printers (AREA)
  • Electronic Switches (AREA)
EP84307545A 1983-11-18 1984-11-01 Dot matrix printer Expired EP0144153B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT6820583 1983-11-18
IT68205/83A IT1159628B (it) 1983-11-18 1983-11-18 Perfezionamenti per una stampante a punti

Publications (3)

Publication Number Publication Date
EP0144153A2 EP0144153A2 (en) 1985-06-12
EP0144153A3 EP0144153A3 (en) 1987-12-02
EP0144153B1 true EP0144153B1 (en) 1990-07-25

Family

ID=11308481

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84307545A Expired EP0144153B1 (en) 1983-11-18 1984-11-01 Dot matrix printer

Country Status (5)

Country Link
EP (1) EP0144153B1 (es)
JP (1) JPS60137677A (es)
DE (1) DE3482821D1 (es)
ES (1) ES8601617A1 (es)
IT (1) IT1159628B (es)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100526082C (zh) * 2006-04-28 2009-08-12 光宝科技股份有限公司 用于驱动打印头维护装置的驱动模块

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3394853A (en) * 1966-10-10 1968-07-30 Thomas P. Foley Timing disc for high speed printers
CH486741A (de) * 1968-06-01 1970-02-28 Olympia Werke Ag Einrichtung zum absatzweisen Bewegen eines Triebgliedes für den Transport von Datenträgern
FR2030471A5 (es) * 1969-01-29 1970-11-13 Bull General Electric
IT939793B (it) * 1971-09-06 1973-02-10 Olivetti & Co Spa Dispositivo di scrittura per macchine calcolatrici elettroniche
DE3168437D1 (en) * 1980-04-28 1985-03-07 Matsushita Electric Ind Co Ltd Serial printer
JPS60986A (ja) * 1983-06-17 1985-01-07 Matsushita Electric Ind Co Ltd 紙送り装置

Also Published As

Publication number Publication date
EP0144153A2 (en) 1985-06-12
IT8368205A0 (it) 1983-11-18
DE3482821D1 (de) 1990-08-30
JPH0551468B2 (es) 1993-08-02
JPS60137677A (ja) 1985-07-22
ES537737A0 (es) 1985-10-16
IT1159628B (it) 1987-03-04
EP0144153A3 (en) 1987-12-02
ES8601617A1 (es) 1985-10-16

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