US3907090A - Printer and pressure assembly therefor - Google Patents

Printer and pressure assembly therefor Download PDF

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Publication number
US3907090A
US3907090A US443419A US44341974A US3907090A US 3907090 A US3907090 A US 3907090A US 443419 A US443419 A US 443419A US 44341974 A US44341974 A US 44341974A US 3907090 A US3907090 A US 3907090A
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US
United States
Prior art keywords
head
sheet
carrying member
printer
coil means
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 - Lifetime
Application number
US443419A
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English (en)
Inventor
William E Northfield
Joel S Novak
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Computer Devices Inc
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Computer Devices Inc
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Filing date
Publication date
Application filed by Computer Devices Inc filed Critical Computer Devices Inc
Priority to US443419A priority Critical patent/US3907090A/en
Priority to JP50012932A priority patent/JPS50116050A/ja
Priority to DE19752506871 priority patent/DE2506871A1/de
Application granted granted Critical
Publication of US3907090A publication Critical patent/US3907090A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • B41J19/02—Character- or line-spacing mechanisms with retarding devices, e.g. brakes
    • 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
    • B41J15/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in continuous form, e.g. webs
    • B41J15/04—Supporting, feeding, or guiding devices; Mountings for web rolls or spindles
    • B41J15/06—Supporting, feeding, or guiding devices; Mountings for web rolls or spindles characterised by being applied to printers having stationary carriages
    • 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
    • B41J25/304—Bodily-movable mechanisms for print heads or carriages movable towards or from paper surface
    • B41J25/312—Bodily-movable mechanisms for print heads or carriages movable towards or from paper surface with print pressure adjustment mechanisms, e.g. pressure-on-the paper mechanisms

Definitions

  • ABSTRACT A printer with a high-speed advancing and printing head suitable for printing on thermally sensitive paper, in response to computer commands. Good contact between the printing head and the paper is provided by completion of a magnetic flux circuit formed in part by a flux-carrying means that extends parallel to the travel of the head. This magnetic circuit permits the use of a small, low-inertia printing assembly and thus facilitates high speed movement from one print position to the next. The use of the same magnetic flux circuit for braking of the printing head and carriage by sliding friction upon the paper prevents overshoot and oscillation when the head approaches a new print position.
  • This invention relates to a printer for high-speed printing.
  • One problem associated with such printers for thermal printing is difficulty in'obtaining good thermal contact between the fast advancing printing head and the thermally sensitive paper,-thus causing "indistinct printing.
  • a second problem is that use of heavy mechanical system'sfor increasing contact pressure is'incompatible with high-speed advance, since high mechanical inertia prevents rapid start and stop motion.
  • the platen assembly is elonbetween the gated, extending throughout the width of theprinters,
  • the platen assembly comprises an elongated elastomeric bar 28-held in position by an iron core member 30.
  • This member in vertical cross section as shown in FIGS. 3 and'4 is of U- shape and the elastomeric bar 28 is positioned at the printing head on the paper for ensuring good contact is produced by the completion of a magnetic circuit including a flux-carrying means extending parallel to the advancing path of the head. This permits the application of pressure by means of a small, low-inertia part or armature mounted on the head, which is compatible with rapid advancement of the head for highprinting speeds.
  • Another feature of the invention is a braking system employing a structure as above, to eliminate overshoot and oscillation when the head approaches a new position, thus to increase printing speed.
  • Other features concern the particular structural relationship illustrated in the Figures which enable a compact and effective design to be achieved.
  • FIG. I is a vertical cross-sectional view of the em bodiment taken on lines ll of FIG. 5;
  • FIG. 2 is a perspective view, partially broken away of the embodiment of. FIG. 1;
  • FIG. 3 is a perspective view, partially broken away and on an enlarged scaleof the elements defining the magnetic flux circuit of the invention
  • FIG. 4 is an end view of the elements of FIG. 3 together with thecarriage of the printer.
  • FIG. 5 is a front side view of the printer.
  • a platen assembly 10 and a carriage assembly 12 define a printing system for action upon a sheet 14 of thermosensitivepaper fed upwardly between them.
  • the sheet is fed from a supply roll 16, under a dancer assembly l8,through upper and lower paper guides 20 and 22 respectively, past a feed roll open end of the U-shape 'protruding slightly beyond the end faces 31 of the core member 30;
  • Each leg 30a
  • each leg serving as'a core for a coil, 32a and 32b respectively.
  • Each coil has elongated strands extending the length of the platen on each side of its respective core, turning about theends thereof.
  • the device forms a horse shoe magnet with coils wound and connected to augment each other in the production of flux within core. 30 during energization of the two coils.
  • the platen assembly 10 is joined by end mounts 34 to the housing side plates 36 of the printer.
  • FIG-5 aside view of the preferred embodiment, also illustrates many of these features.
  • the carriage assembly 12- is comprised of four sections: carriage body 38, carriage bearings 40, printing head assembly 42 andplate 44 forming a cable restraint and a photocell flag tab used in conjunction with a-photocell (not shown) to indicate approach to the zero position upon carriage return.
  • the carriage body '38 is mounted on shaft 26 via carriage bearings 40, thereby to permit the carriage assembly to advance freely along the shaft in an axial direction and to rotate freely upon the shaft, thereby allowing the printing head assembly to.increase or decrease its pressure upon sheet 14 duringoperation of the printer.
  • Printing head assembly 42 (FIGS. 3, 4) comprises a printing element 46'and a ceramic mounting block 48.
  • Printing element 46 provides an assemblage of'silicon transistors mounted to form a 5 X 7 matrix of thirty-five heatable dots or elements with drive electronics and temperature compensation built into the printing element.
  • a suitable printing element is Model DC 1157012 Thermal Print Head'5 x. 7 Dot Matrix manufactured by Displaytek Corp.
  • the ceramic mounting block 48 attaches the printing element to carriage body 38 and carries electrical leads and contacts by means of which electrical power and sig nals can be transmitted to the printing element.
  • the printing element 46 is mounted at the upper left edge of block 48 (relative to the operator, or right edge when viewed from the back as in FIG. 3) to permit the operator to read a character immediately after it has been printed.
  • a flexible harness 50 extends from plate 44 on carriage assembly 12 to printed circuit board 52, which provides the logic for actuating the various dots in the.
  • paper advance drive 62 are controlled by power circuits on a second printed circuit board (not shown) mounted parallel to housing endplate 36.
  • Crucial to effective printing is the amount of pressure with which the printing head bears upon the sheet.
  • the pressure is needed to make good thermal contact between each dot in the matrix and the paper despite watermarks and grain in the paper itself.
  • the force of the head against the paper is provided by interaction of the platen magnet previously described with a force clip member 60.
  • the printing head assembly 42 is mounted on carriage assembly 12 with two small screws.
  • Force clip member 60 is comprised of an H-shaped piece of ferro magnetic material having legs 60a, 60b joined by bridge 600 (P16.
  • Paper is advanced through the printer by means of a paper stepper motor 62 and paper timing pulley and belt 64 and 66 respectively. This drives a roller shaft 68 against which the paper is pushed by pinch rollers 70.
  • the paper feed system 72 is comprised of two end supports which hold the paper roll in the printer frame. One end is a free turning pivot point. The other is comprised of a spring and washer arrangement 74. The frictional action between the washer and a slide plate prevents unrolling of the paper under light vibration.
  • the printer In a typical use the printer is employed in a remote terminal such as might be carried by a salesman and connected to a computer by telephone line.
  • the control logic of the printer receives instructions fromthe computer and initiates a series of letter or symbol commands. Each of these commands involves a cycle which includes a print operation followed by a carriage movement operation. In a typical cycle the following steps occur: At time zero the electromagnet 32 is energized to a first current level, increasing the force applied by the force clip and the U core which brings the printing element into good thermal contact with the paper, regardless of the particular position of the printing head along the width of the paper.
  • both the paper and the elastomeric bar are slightly compressed by the pressure, as a matter of design the pressure being determined by appropriate selection of the elastomeric bar and the current level.
  • the printing elements i.e., those dots needed for the printing of the selected letter or symbol, are turned on for a period of approximately 6 to 12 milliseconds, the
  • electromagnet remaining energized at the first current level during this period to provide good thermal contact.
  • the paper changes color due to its thermochemical properties and a letter or symbol is produced on the paper.
  • a short time of the order of a millisecond is allowed to permit cooling of the print element and to permit collapse of the magnetic field, the magnet 32 having been de-energized to a second, lower current level.
  • the carriage advance stepper motor is now energized to advance the carriage one character position along shaft 26, the head sliding on the paper, the lower level of energization ensuring that the head does not move away from the paper.
  • braking to reduce overshoot and oscillation is provided by a momentary electrical pulse (eg to the first current level) through the electromagnet coils, providing increased frictional force between the printer head assembly and the paper, (and with momentary compression of the elastomeric bar by the head acting through the paper) as the head slides thereupon.
  • the head comes to rest much more quickly than it would without the braking pulse.
  • the total time for this cycle is approximately 16-20 milliseconds and the logic circuitry is now ready for the next instruction.
  • the carriage is allowed to advance 81 print positions across the page.
  • the 81st position initiates a carriage return as can also be done with an external command.
  • the electromagnet By the positioning of the electromagnet in the relation shown a very effective printer construction is achieved, e.g. it provides ready visibility of the printout as it occurs, etc. However it is possible under certain circumstances to provide the elongated electromagnet on the same side of the sheet as the print head and armature, eg in an arrangement where an armature associated with the head (e.g. protruding to the front from mounting block 48) serves to push the head against the paper instead of the pull arrangement shown.
  • an armature associated with the head e.g. protruding to the front from mounting block 48
  • a thermal printer for printing successive lines of selected discrete characters upon a sheet
  • the printer comprising a thermal printing head having a multiplicity of energizable and de-energizable print points positioned over an area for defining the desired characters by selective energization of respective sets of said print points by a character control circuit, a carriage means for advancing said head stepwise across said sheet to a plurality of discrete character positions and for returning said head, a sheet transport mechanism for advancing said sheet lengthwise after the printing of each line, and a pressure applying system for causing said thermal printing head to thermally contact said sheet
  • said pressure applying system is an electromagnetic system comprising a first flux carrying member attached to and secured to move with said head and carriage, said flux carrying member having at least a pair of spaced apart faces, and a second flux carrying member which is elongated, extends parallel to the path of advance of said head and presents a pair of elongated faces opposed and parallel to respective faces of the first said flux carrying member, at least
  • said con- 7 trol circuitry is adapted to selectively energize said coil means to a first level at the time of energizing said thermal head to press said printing head firmly against said sheet for printing a character and after said printing to dc-en ergize said coil means to a second level, lower than the first, reducing pressure of said head upon said sheet to enable advancing movement of said head while said head remains in sliding contact with said sheet under the influence of said coil means.
  • control circuitry is adapted during advancing movement of said head to energize said electromagnetic coil means to brake said carriage by sliding friction of said head upon said sheet as said head approaches a new discrete print position.
  • said first flux carrying member comprises a ferromagnetic armature and said second flux carrying member is associated with said coil means.
  • said second flux carrying member comprises a pair of legs extending in parallel throughout the range of movement of said carriage, said legs connected to each other by a bridge member throughout their length and free portions of said legs defining a pair of pole faces disposed for interaction with said armature to complete said magnetic circuit.
  • said coil means comprises two coils, one wound about and throughout said extent of each of said legs.
  • the printer of claim 10 further including an elongated elastomeric mass extending parallel to said second flux carrying member, said mass defining a surface parallel to the surface of said sheet, said surface being opposed to said thermal printing head and projecting beyond said flux carrying member toward said sheet.
  • said armature comprises a plurality of leg members connected by a bridge means, each of said armature leg members positioned closely in opposition to a leg member of said second flux carrying member.
  • the printer of claim 4 further including an elongated elastomeric mass extending parallel to the path of said carriage and head, said mass defining a surface parallel to the surface of said sheet, and being opposed to said head, on the opposite side of said sheet therefrom, and said control circuitry adapted to energize said coil means during a braking period before said head comes to rest in a new discrete print position and to energize said coil means while said head is at rest and thermal printing elements of said head are energized, to press said head against said sheet and thereby compress said elastomeric mass.
  • control circuitry is adapted to receive commands from a computer and in response thereto to initiate a printing cycle including energization of said print head and energization and de-energization of said electromagnet coil means

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  • Common Mechanisms (AREA)
  • Electronic Switches (AREA)
  • Character Spaces And Line Spaces In Printers (AREA)
US443419A 1974-02-19 1974-02-19 Printer and pressure assembly therefor Expired - Lifetime US3907090A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US443419A US3907090A (en) 1974-02-19 1974-02-19 Printer and pressure assembly therefor
JP50012932A JPS50116050A (enrdf_load_stackoverflow) 1974-02-19 1975-01-30
DE19752506871 DE2506871A1 (de) 1974-02-19 1975-02-18 Drucker

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Application Number Priority Date Filing Date Title
US443419A US3907090A (en) 1974-02-19 1974-02-19 Printer and pressure assembly therefor

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US3907090A true US3907090A (en) 1975-09-23

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JP (1) JPS50116050A (enrdf_load_stackoverflow)
DE (1) DE2506871A1 (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016572A (en) * 1976-03-15 1977-04-05 Graphic Controls Corporation Thermographic stylus with inherent pressure control
US4023184A (en) * 1975-10-06 1977-05-10 Mfe Corporation Thermal matrix type printing head
US4024942A (en) * 1974-11-08 1977-05-24 Copal Company Limited Printer with a paper guide separate from the printer frame
US4195937A (en) * 1977-09-19 1980-04-01 Termcom, Inc. Electroresistive printing apparatus
WO1982000443A1 (en) * 1980-07-31 1982-02-18 A Douglas Modular electronic measuring and printing unit
JPS5757951U (enrdf_load_stackoverflow) * 1980-09-25 1982-04-05
US4441425A (en) * 1982-02-17 1984-04-10 Monarch Marking Systems, Inc. Printing apparatus
US4536096A (en) * 1979-12-26 1985-08-20 Branson Terry L Print head carriage mechanism including a drive belt
US4746766A (en) * 1987-03-11 1988-05-24 Wang Laboratories, Inc. Shielded flexing connector
US5838345A (en) * 1996-06-21 1998-11-17 Eastman Kodak Company Apparatus for maintaining the positional relationship of a print head

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58194054U (ja) * 1982-06-21 1983-12-23 セイコーインスツルメンツ株式会社 シリアルプリンタのヘツドキヤリア

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955895A (en) * 1958-01-02 1960-10-11 Cardiotron Electro Medical Lab Cardiograph stylus calibrations
US3115382A (en) * 1962-10-02 1963-12-24 Leighton L Morse Rectilinear recording stylus
US3159710A (en) * 1959-12-23 1964-12-01 Litton Systems Inc Pressure-responsive recording having magnetically biased marking mechanism
US3638197A (en) * 1968-12-31 1972-01-25 Texas Instruments Inc Electronic printing input-output station
US3754278A (en) * 1971-12-01 1973-08-21 American Micro Syst Thermal printing system
US3804008A (en) * 1971-08-24 1974-04-16 Potter Instrument Co Inc Hammer actuating mechanism and drum design for printers

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955895A (en) * 1958-01-02 1960-10-11 Cardiotron Electro Medical Lab Cardiograph stylus calibrations
US3159710A (en) * 1959-12-23 1964-12-01 Litton Systems Inc Pressure-responsive recording having magnetically biased marking mechanism
US3115382A (en) * 1962-10-02 1963-12-24 Leighton L Morse Rectilinear recording stylus
US3638197A (en) * 1968-12-31 1972-01-25 Texas Instruments Inc Electronic printing input-output station
US3804008A (en) * 1971-08-24 1974-04-16 Potter Instrument Co Inc Hammer actuating mechanism and drum design for printers
US3754278A (en) * 1971-12-01 1973-08-21 American Micro Syst Thermal printing system

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4024942A (en) * 1974-11-08 1977-05-24 Copal Company Limited Printer with a paper guide separate from the printer frame
US4023184A (en) * 1975-10-06 1977-05-10 Mfe Corporation Thermal matrix type printing head
US4016572A (en) * 1976-03-15 1977-04-05 Graphic Controls Corporation Thermographic stylus with inherent pressure control
US4195937A (en) * 1977-09-19 1980-04-01 Termcom, Inc. Electroresistive printing apparatus
US4536096A (en) * 1979-12-26 1985-08-20 Branson Terry L Print head carriage mechanism including a drive belt
WO1982000443A1 (en) * 1980-07-31 1982-02-18 A Douglas Modular electronic measuring and printing unit
JPS5757951U (enrdf_load_stackoverflow) * 1980-09-25 1982-04-05
US4441425A (en) * 1982-02-17 1984-04-10 Monarch Marking Systems, Inc. Printing apparatus
US4746766A (en) * 1987-03-11 1988-05-24 Wang Laboratories, Inc. Shielded flexing connector
US5838345A (en) * 1996-06-21 1998-11-17 Eastman Kodak Company Apparatus for maintaining the positional relationship of a print head

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Publication number Publication date
DE2506871A1 (de) 1975-12-04
JPS50116050A (enrdf_load_stackoverflow) 1975-09-11

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