US3848720A - Pressure spring for a thermoprinter - Google Patents

Pressure spring for a thermoprinter Download PDF

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Publication number
US3848720A
US3848720A US00394245A US39424573A US3848720A US 3848720 A US3848720 A US 3848720A US 00394245 A US00394245 A US 00394245A US 39424573 A US39424573 A US 39424573A US 3848720 A US3848720 A US 3848720A
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United States
Prior art keywords
printing plate
leaf spring
thermoprinter
line
printing
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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
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US00394245A
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English (en)
Inventor
H Carlsen
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Contex Calculators AS
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Contex Calculators AS
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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
    • 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

  • thermoprinter for use, for example, in electronic table calculators and curve recorders, in which a thermosensitive recording strip is advanced step by step across a printing plate having a line of type of an electric resistance material, which are selectively energizable by heating current, and is pressed into contact with the printing plate during the printing of each line by a pressing device including a leaf spring extending across the printing plate with such a curvature in its unloaded condition that a convex lateral surface of the spring faces the printing plate, said leaf spring being relieved from the pressure contact when the carrier is to be advanced by an actuator forming part of the advancing mechanism and applying local bias forces in the direction away from the printing plate in points on the leaf spring situated at a short distance from either end thereof.
  • the present invention relates to a thermoprinter of the type in which a printing plate with controllable circuits actuates a thermosensitive recording material line by line, said recording material being advanced step by step across the printing plate by means of an advancing mechanism and being pressed against the printing plate during the recording process by a pressing means.
  • Thermoprinters can be utilized in connection with many different devises, for example, for writing out measuring and calculating results.
  • ever-increasing demands are made with respect to the speed of printing and the uniformity of the blackening of the printed characters while, at the same time, increasing demands for a reduction in the noise level are also put forward.
  • the printing speed is increased and the uniformity of the blackening is improved if, in the writing out process, the total number of figures or other individual characters or symbols in a line are written out in two or more stages in stead of being printed one by one, by employing types for the recording which are composed of a few uniform type segments that are constructed as electric resistors, e.g., by thin film technology, having a shape corresponding to the type segments desired.
  • the individual types on the printing plate may be composed identically of the same number of type segments and the printing of a symbol in the form of a given figure is then carried out by actuating the segments of the type in question corresponding to the shape of this figure.
  • the recording is effected by means of heat transfer from the electric resistors on the printing plate to the thermosensitive recording material, it is desirable to have a direct mechanical contact between the printing plate and the recording material, the electric resistors being, however, covered with a wear resistant layer such as quartz, which can be applied by a sputtering process, in order to reduce wear and tear.
  • a wear resistant layer such as quartz
  • thermosensitive recording material normally consists of paper which is provided on one side with a thermosensitive coating which, in case of local heat transfer contact with a type segment constructed as an electric resistor, melts or evaporates on the spot in question.
  • thermosensitive coating material is hereby deposited on the printing plate which in the course of time may result in a substantial non-uniformity of the blackening due to the differences in the frequency with which the individual types on the printing plate are used for recording, provision is normally made for the thermosensitive coating of the recording paper to face away from the printing plate.
  • the invention is based on the recognition of the fact that the problem is chiefly to be sought in the pressing means which, in prior art thermoprinters, is constituted of a rigid rail member of a pivotable, frame-shaped holder which, precisely with a view to obtaining a good and uniform contact with the printing plate is of strong construction and is actuated by a relatively powerful spring, against the spring force of which the frame has to move when the pressure on the paper is relieved in order to advance the paper.
  • thermoprinter is characteristic in that the pressing means is a leaf spring supported at its ends in a holder, said spring having in its unloaded condition a curvature with the convex lateral surface facing towards the printing plate and being adapted for being biased in the direction away from the printing plate at a short distance from the supporting elements.
  • thermoprinter accord ing to the invention, the relief and springing movements are left solely to the pressing means proper which is self-adjusting in its longitudinal direction. Thus, only the leaf spring is moved during the operation. The result of this is that the masses to be accelerated and retarded become significantly smaller, which is also reflected in a substantial noise level reduction.
  • the leaf spring is fitted in the holder so as to be rotatable a small angle around its longitudinal axis.
  • the leaf spring is preferably detachably mounted so that it can be easily replaced. This is particularly important if the spring is coated with a softer material that is susceptible to damage or ageing. Such damage may occur, for instance, if the thermoprinter is operated without any recording material so that the soft material, e.g., felt or foam plastic, burns or melts when coming into contact with the heated printing plate or as a consequence of contact between said soft material and the prepared side of the recording material.
  • the leaf spring is adapted for actuation by an electromagnetic activator.
  • the actuating mechanism be adapted to be controlled in such a way that the pressing means is relieved as soon as recording has been effected on the thermosensitive material. Moreover, this results in the advantage that the softer, pressure-equalizing material on the leaf spring is automatically relieved when the thermoprinter is inoperative so that a permanent deformation of this material during prolonged rest periods is avoided.
  • FIG. 1 is a perspective view of the parts of an embodiment of a thermoprinter according to the invention which are necessary for understanding the invention
  • FIGS. 2, 3 and 4 show the interaction between a printing plate and a pressing means for the recording material in FIG. 1 in a purely schematic manner
  • FIG. 7 shows a supporting element for the pressing means
  • FIG. 8 shows a modification of the actuating mechanism in FIG. 5.
  • the printing process may be divided into two or more stages as mentioned in the foregoing in each of which current is supplied to resistor elements forming identical type elements of the types.
  • those type elements located in upper half of all types which are intended to be printed may be energized in a first stage and, in a subsequ3nt stage, energization of the type elements intended for printing which are located in the lower half of the types can take place together with energization of one out of a number of additional resistor elements (not shown) located between the character types was to produce a decimal comma. Thereby, a substantially inform heating of the printing plate is achieved during said recording stages.
  • thermoprinter the printing plate is in contact during the recording process with the unprepared side of the recording paper so that the atomic components of the preparation evaporated during the printing process cannot attack the printing plate.
  • FIG. 2 shows the pressure spring in its unloaded condition, in which holding frame 4 is pivoted away from the printing plate, said holding frame being pivotably connected by means of a shaft 5 to the side plates of the thermoprinter as shown at 6, and being locked in said unloaded condition relative to said side plates with the aid of snap means, as shown with dotted lines at 7, engaging locking flanges which project perpendicularly from the side plates as shown with dotted lines at 8.
  • the pressure spring is shaped so as to have, in said unloaded condition, a curvature with the convex lateral surface facing towards the printing plate.
  • pressure spring 3 is shown in contact with printing plate 1.
  • the spring is provided on the side facing towards printing plate 1 with a coating 9 of a soft material, e.g., a felt or velvet-like textile material.
  • pressure spring 3 is subjected to biasing forces in the direction away from the printing plate at a short distance from each of its ends supported in holder 4 by means of actuating arms 10 forming parts of an actuating mechansim described in the following in order to effect paper advancement.
  • the spring acquires a curvature with the concave lateral surface facing towards printing plate 1.
  • each of actuating arms 10 constitutes one arm of a two-armed lever which is rotatably supported on a through shaft 11 upon which a paper advancing roller 12 is mounted.
  • the other arm 13 of the lever which forms an angle of approximately 90 to arm 10 is provided of its outer end with a flange 14 acting as a cam follower by being engaged by a cam disc 15 which is rigidly mounted on a drive shaft 16 which can be turned by a driving means described in the following through an angle of approximately between the positions shown in solid and dotted lines, respectively, in FIG. 5.
  • the driving means for cam disc shaft 16 comprises two electromagnetic activators 22 and 23 having U-shaped, lamellated soft iron yokes 24 and 25 the legs of which carry series-connected coils 26, 27 and 28, 29, respectively, and at the ends. of which legs pole pieces are formed with circular recesses matching the terminal faces of two lamellated soft iron armatures and 31, respectively, which are rigidly secured on shaft 16.
  • Armatures 30 and 31 are mounted in such a way on shaft 16 that their planes of symmetry through the shaft are mutually displaced by an angle of approximately 75 so that, in the position shown in which armature 30 has its terminal faces located in recesses in yoke 24, armature 31 assumes a position in which a small portion of its terminal face extends into the recess in 25.
  • the position shown in FIG. 6 corresponds to the solid line position of the actuating mechansim shown in FIG. 5 in which pressure spring 3 presses the recording paper against printing plate 1.
  • the actuating mechanism in FIG. 5 is to be activated for paper advancement and for biasing pressure spring 3 in the direction away from printing plate 1
  • the coils 28, 29 on yoke 25 are supplied with current while coils 26, 27 are without current whereby armature 31, under the influence of the magnetic field produced, is turned in the direction of the arrow into the position which, in the figure, is shown for the other armature 30, and hereby shaft 16 and cam discs 15 are turned through an angle of approximately 75 into the position shown by dotted lines in FIG. 5.
  • the energization of activators 22 and 23 may advantageously be effected in such a way that, in the inoperative periods of the device, pressure spring 3 will invariably assume the condition shown in FIG. 4 so that deformation of the recording paper during a prolonged rest period is avoided, which means that the individual components of the actuating mechanism will as a rest position assume the position shown in dotted lines in FIG. 5.
  • This can be achieved by arranging the operating cycle of the recording process in such a manner that, prior to the actual recording period where the printing elements are actuated, there comes a period in which activator 22 is energized so that the actuating mechanism is made to assume the position shown in solid lines in FIG. 5 whereby pressure spring 3 is brought into the position shown in FIG. 3 and, immediately subsequent to the recording period, there follows a period in which activator 23 is energized so as to bring pressure spring 3 into the position shown in FIG. 4 and to turn roller 12 one step.
  • thermoprinter With respect to the working speed of the thermoprinter it has been found that 20 msec are available for each of the said actuation periods since the remaining part of the total working cycle is taken up by the recording process proper.
  • thermoprinter according to the invention that only small masses have to be moved and retarded when removing the pressing means from the printing plate and returning it into contact with the plate, that is to say, the masses of the pressure spring 3 and the elements of the actuating mechanism which may be constructed chiefly of light-weight materials, whereas the movement of the relatively heavy holder 4 is avoided.
  • FIG. 8 shows purely schematically a modification of the actuating mechansim in FIG. 5, in which actuating arm 10 serving to bias pressure spring 3 in the direction away from printing plate 1, and a corresponding actuating arm on the opposite side of the thermoprinter, are interconnected via a through flange portion 35 and are pivotably journalled on a shaft 36 which is mounted in the side walls of the thermoprinter.
  • actuating arm 10' in FIG. 5 is interconnected via a through flange portion 35 and are pivotably journalled on a shaft 36 which is mounted in the side walls of the thermoprinter.
  • thermoprinter comprising a supporting frame
  • pressing means for pressing said strip into contact with said printing plate during the printing of each line
  • said pressing means including a holder connected with said supporting frame, a leaf spring supported at its end in said holder in operative relation to the printing plate and extending in the line direction thereof with such a curvature in its unloaded condition that a convex lateral surface of the leaf spring faces the printing plate, and means for locking said holder to said supporting frame in a position in which said leaf spring is pressed against the printing plate with a substantially uniformly distributed pressure in the length direction of the leaf spring;
  • said mechanism including actuator means for applying local bias forces in the direction away from the printing plate in points on said leaf spring situated a short distance from either end thereof supported in said holder, whereby the leaf spring is relieved from pressure contact with the printing plate when said I strip is to be advanced.
  • thermoprinter as claimed in claim 1, wherein the leaf spring is supported in said holder so as to be pivotable through a small angle about its longitudinal axis.
  • thermoprinter as claimed in claim 1, wherein said holder is provided with bearings for detachably mounting the ends of said leaf spring.
  • thermoprinter as claimed in claim 1, wherein said advancing mechanism comprises an electromagnetic actuator.
  • thermoprinter as claimed in claim 7, wherein means are provided for energizing said actuator for advancing said strip and relieving said leaf spring from pressure contact with the printing plate immediately subsequent to the printing of each line on the strip.

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US00394245A 1973-03-05 1973-09-04 Pressure spring for a thermoprinter Expired - Lifetime US3848720A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DK117573AA DK129605B (da) 1973-03-05 1973-03-05 Termoskriver.

Publications (1)

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US3848720A true US3848720A (en) 1974-11-19

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US00394245A Expired - Lifetime US3848720A (en) 1973-03-05 1973-09-04 Pressure spring for a thermoprinter

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US (1) US3848720A (enrdf_load_stackoverflow)
JP (1) JPS5339140B2 (enrdf_load_stackoverflow)
DE (1) DE2344406C3 (enrdf_load_stackoverflow)
DK (1) DK129605B (enrdf_load_stackoverflow)
FR (1) FR2220382A1 (enrdf_load_stackoverflow)
GB (1) GB1436036A (enrdf_load_stackoverflow)
IT (1) IT1010598B (enrdf_load_stackoverflow)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013159A (en) * 1974-05-30 1977-03-22 Copal Company Limited Printer having a limited movement platen and/or printing head and independent supports therefor
US4024942A (en) * 1974-11-08 1977-05-24 Copal Company Limited Printer with a paper guide separate from the printer frame
US4098389A (en) * 1976-08-20 1978-07-04 Bunker Ramo Corporation Three position platen control mechanism
US4133422A (en) * 1975-08-14 1979-01-09 Alps Electric Co., Ltd. Typing machine
US4170422A (en) * 1975-02-03 1979-10-09 Texas Instruments Incorporated Printhead alignment mechanism
US4236834A (en) * 1978-09-28 1980-12-02 International Business Machines Corporation Electrothermal printing apparatus
US4322044A (en) * 1980-06-23 1982-03-30 Texas Instruments Incorporated Paper alignment and loading apparatus
US4358776A (en) * 1979-06-22 1982-11-09 Kabushiki Kaisha Suwa Seikosha Thermal printer and improved platen
US4401391A (en) * 1980-04-28 1983-08-30 Matsushita Electric Industrial Co., Ltd. Serial printer
US4443125A (en) * 1980-12-27 1984-04-17 Epson Corporation Printer
EP0126903A3 (en) * 1981-05-29 1985-07-10 Monarch Marking Systems, Inc. Hand-held labeler
US4838713A (en) * 1985-08-20 1989-06-13 Sanyo Electric Ltd. Thermal transfer printer head position homing mechanism
US4959666A (en) * 1985-03-25 1990-09-25 Canon Kabushiki Kaisha Image forming apparatus having a platen and recording means elastically pressed together
EP0458461A3 (en) * 1990-05-25 1992-04-15 Hewlett-Packard Company Self-aligning thermal print head and paper loading mechanism
US5223859A (en) * 1985-03-28 1993-06-29 Canon Kabushiki Kaisha Image formation apparatus with means for capping a recording head assembly
US5262872A (en) * 1985-03-28 1993-11-16 Canon Kabushiki Kaisha Image forming apparatus with means for error detection
US20080043061A1 (en) * 2006-05-23 2008-02-21 Nuventix, Inc. Methods for reducing the non-linear behavior of actuators used for synthetic jets

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49127996A (enrdf_load_stackoverflow) * 1973-04-17 1974-12-07
JPS5165010U (enrdf_load_stackoverflow) * 1974-11-15 1976-05-22
GB2033843B (en) * 1978-11-08 1983-01-06 Leeds & Northrup Ltd Thermal printer platen
US4658270A (en) * 1983-07-27 1987-04-14 Sharp Kabushiki Kaisha Recording apparatus

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161457A (en) * 1962-11-01 1964-12-15 Ncr Co Thermal printing units
US3744611A (en) * 1970-01-09 1973-07-10 Olivetti & Co Spa Electro-thermic printing device
US3754278A (en) * 1971-12-01 1973-08-21 American Micro Syst Thermal printing system
US3787886A (en) * 1973-01-04 1974-01-22 Displaytek Corp Advancing mechanism for thermal print apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161457A (en) * 1962-11-01 1964-12-15 Ncr Co Thermal printing units
US3744611A (en) * 1970-01-09 1973-07-10 Olivetti & Co Spa Electro-thermic printing device
US3754278A (en) * 1971-12-01 1973-08-21 American Micro Syst Thermal printing system
US3787886A (en) * 1973-01-04 1974-01-22 Displaytek Corp Advancing mechanism for thermal print apparatus

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013159A (en) * 1974-05-30 1977-03-22 Copal Company Limited Printer having a limited movement platen and/or printing head and independent supports therefor
US4024942A (en) * 1974-11-08 1977-05-24 Copal Company Limited Printer with a paper guide separate from the printer frame
US4170422A (en) * 1975-02-03 1979-10-09 Texas Instruments Incorporated Printhead alignment mechanism
US4133422A (en) * 1975-08-14 1979-01-09 Alps Electric Co., Ltd. Typing machine
US4098389A (en) * 1976-08-20 1978-07-04 Bunker Ramo Corporation Three position platen control mechanism
US4236834A (en) * 1978-09-28 1980-12-02 International Business Machines Corporation Electrothermal printing apparatus
US4358776A (en) * 1979-06-22 1982-11-09 Kabushiki Kaisha Suwa Seikosha Thermal printer and improved platen
US4401391A (en) * 1980-04-28 1983-08-30 Matsushita Electric Industrial Co., Ltd. Serial printer
US4322044A (en) * 1980-06-23 1982-03-30 Texas Instruments Incorporated Paper alignment and loading apparatus
US4443125A (en) * 1980-12-27 1984-04-17 Epson Corporation Printer
EP0126903A3 (en) * 1981-05-29 1985-07-10 Monarch Marking Systems, Inc. Hand-held labeler
US4959666A (en) * 1985-03-25 1990-09-25 Canon Kabushiki Kaisha Image forming apparatus having a platen and recording means elastically pressed together
US5223859A (en) * 1985-03-28 1993-06-29 Canon Kabushiki Kaisha Image formation apparatus with means for capping a recording head assembly
US5262872A (en) * 1985-03-28 1993-11-16 Canon Kabushiki Kaisha Image forming apparatus with means for error detection
US4838713A (en) * 1985-08-20 1989-06-13 Sanyo Electric Ltd. Thermal transfer printer head position homing mechanism
EP0458461A3 (en) * 1990-05-25 1992-04-15 Hewlett-Packard Company Self-aligning thermal print head and paper loading mechanism
USRE35026E (en) * 1990-05-25 1995-08-22 Hewlett-Packard Corporation Self-aligning thermal print head and paper loading mechanism
US20080043061A1 (en) * 2006-05-23 2008-02-21 Nuventix, Inc. Methods for reducing the non-linear behavior of actuators used for synthetic jets
US8672648B2 (en) * 2006-05-23 2014-03-18 Nuventix, Inc. Methods for reducing the non-linear behavior of actuators used for synthetic jets

Also Published As

Publication number Publication date
DK129605C (enrdf_load_stackoverflow) 1975-03-24
DE2344406A1 (de) 1974-09-19
DE2344406C3 (de) 1975-11-06
DK129605B (da) 1974-10-28
IT1010598B (it) 1977-01-20
GB1436036A (en) 1976-05-19
FR2220382A1 (enrdf_load_stackoverflow) 1974-10-04
JPS5026551A (enrdf_load_stackoverflow) 1975-03-19
DE2344406B2 (de) 1975-03-20
JPS5339140B2 (enrdf_load_stackoverflow) 1978-10-19

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