EP0490643B1 - Imprimantes à impact - Google Patents

Imprimantes à impact Download PDF

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Publication number
EP0490643B1
EP0490643B1 EP19910311480 EP91311480A EP0490643B1 EP 0490643 B1 EP0490643 B1 EP 0490643B1 EP 19910311480 EP19910311480 EP 19910311480 EP 91311480 A EP91311480 A EP 91311480A EP 0490643 B1 EP0490643 B1 EP 0490643B1
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EP
European Patent Office
Prior art keywords
hammer
speed
platen
impact
character
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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
Application number
EP19910311480
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German (de)
English (en)
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EP0490643A2 (fr
EP0490643A3 (en
Inventor
Johannes F. Gottwald
Dennis W. Gruber
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Xerox Corp
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Xerox Corp
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Publication of EP0490643A3 publication Critical patent/EP0490643A3/en
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Publication of EP0490643B1 publication Critical patent/EP0490643B1/fr
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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
    • B41J9/00—Hammer-impression mechanisms
    • B41J9/44—Control for hammer-impression mechanisms

Definitions

  • This invention relates to a controlled low frequency impact system for a quiet impact printer, wherein variable impact speeds are utilized to impart different amounts of kinetic energy to character elements of different size, and to an inexpensive system for precise bidirectional motor control without the need for direction information from the feedback sensor.
  • the office has, for many years, been a stressful environment because of the large number of objectionable noise generators, such as typewriters, high-speed impact printers, paper shredders, and other office machinery. Where several such devices are placed together in a single room, the cumulative noise pollution may even be hazardous to the health and well being of its occupants.
  • the situation is well recognized and has been addressed by governmental bodies which have set standards for maximum acceptable noise levels in office environments. Attempts have been made by office machinery designers, in the field of impact printers, to reduce the noise pollution.
  • Some of these methods include enclosing impact printers in sound-attenuating covers; designing impact printers in which the impact noise is reduced, and designing quieter printers based on non-impact technologies, such as ink jet and thermal transfer.
  • the low-cost personal typewriter is purchased primarily for home usage (including both personal and in-home office) and for school usage. It is particularly desirable in these environments to reduce the acoustic noise level of the printing mechanism, at the source, to levels which are unobtrusive. For example, in the home, other members of the family should not be distracted by the clatter of typing if conducted in common rooms. In a secondary school or college setting, colleagues and others should not be disturbed if the user types in a library, a study hall or a dormitory room. Heretofore such usage has not been possible because typewriters are notoriously noisy devices. The quiet operation of the low-cost typewriter of this invention will enable such usage, because quietness transports such useful appliances into new physical settings and enhances portability. A derived benefit will be freer communication among work group members, as the user is able to work directly in the group in a non-irritating manner.
  • Noise measurements are often referenced as dB or dBA values, wherein the "A" scale represents humanly-perceived levels of loudness, as opposed to absolute values of sound intensity.
  • the scale is logarithmic, and that a 10 dB difference equals a factor of 10, a 20 dB difference equals a factor of 100, a 30 dB equals a factor of 1000, and so on.
  • Typical typewriters generate impact noise in the range of 65 dBA to just over 80 dBA, when measured at the operator's position. These sound levels are deemed to be intrusive.
  • the IBM Selectric ball unit generates about 78 dBA
  • the Xerox Memorywriter generates about 68 dBA
  • the low-cost Smith Corona Correcting Portable generates about 70 dBA.
  • the noise is identified as being objectionable or annoying. It would be highly desirable to reduce the impact noise to a value in the vicinity of 50 dBA.
  • the low-cost typewriter of the present invention has been typically measured at about 50 dBA, representing a dramatic improvement, on the order of about 100 times less sound pressure, over presently-available low-cost typewriters.
  • the major source of noise in the modern typewriter is produced as the hammer impacts and drives a character pad to form an impression on a receptor sheet.
  • Character pads are carried upon and transported past a print station at the ends of the rotating spokes of a printwheel. When a selected character is to be printed, it is stopped at the print station and a hammer drives it against a ribbon, the receptor sheet and a supporting platen, with sufficient force to release ink from the ribbon onto the receptor sheet.
  • the duration of platen deformation by the very small impacting hammer mass is very short, of the order of 100 microseconds. Intuitively it is known that a rapid impact will be noisy and that a slow impact will be quieter. Thus, if the impact duration were longer it would be possible to make the device quieter. In typewriters with printing speeds in the 10 to 12 characters per second range, the mean time available between character impacts is about 85 to 90 milliseconds. Clearly, more of that available time can be used for the hammer impact than the usual 100 microseconds. If, for example, the platen deformation time were stretched to even 5 to 10 milliseconds, this would represent a fifty-to one hundred-fold increase in the impact pulse width.
  • US-A-4,681,469 discloses greatly increasing the effective mass of the hammer, introducing the hammer to the platen at a relatively-slow speed, and causing the platen deformation to take place over an extended period.
  • US-A-4,668,112 discloses controlling the movement of the hammer throughout its path of movement from its home position to its application of impact force to the platen. As the hammer nears the surface of the platen its speed is significantly diminished by a braking action of the drive motor, so that impact takes place at a very slow speed. Subsequent to initiation of contact, the drive motor is reenergized, increasing the hammer force to deform the platen.
  • a mass transformer comprising a heavy rockable bail bar driven by a voice coil motor, urges a push rod toward and away from the platen in a controlled manner.
  • the push rod in turn moves a print tip (hammer) into deforming contact with the platen.
  • a sensor mounted upon the print tip indicates the moment of contact with the platen, so that an additional application of kinetic energy may be provided by the voice coil motor at that juncture.
  • a suitable controller energizes the voice coil motor to move the print tip across a throat distance between its home position and the surface of the platen, where its speed is very slow. After contact has been sensed, the controller again energizes the voice coil motor for imparting a predetermined force for deforming the platen to release ink from the ribbon with this high effective mass.
  • a low cost implementation of a quiet impact printer based upon the principles of operation of the '469 and '112 patents, is described in copending patent application U.S. Serial No. 07/510,654 (Babler et al ) assigned to the same assignee as the instant application, whose disclosure is herein fully incorporated by reference.
  • a high effective mass hammer is driven toward and away from the platen, by a DC motor acting through a displacement and force modifying mechanism, in a timed manner.
  • the present invention may be carried out, in one form, by providing an impact printer comprising a platen, a carriage mounted for reciprocating movement generally parallel to the platen, a rotatable print element having character-imprinting portions disposed thereon, the characters being assigned a class designation according to their imprinting area, a print element selector for moving the print element to position a selected character portion at a printing position, a hammer for driving the character portions to deform the platen, and means for driving the hammer toward and away from the platen.
  • the carriage supports the print element, the selector, the hammer and the driving means.
  • the invention comprises means for assigning different impact speeds to the hammer in accordance with the character portion class designations, means for varying the rate of hammer displacement as it is moved from a home position to an impact position, so that the hammer initially moves through a first region at an increasing speed and subsequently moves through a second region at a substantially-constant speed, and means for controlling the attainment of the impact speeds, including means for incrementing a counter periodically in response to the hammer movement for determining the instantaneous location and speed of the hammer, and means for resetting the counter with a predetermined count, notwithstanding the actual count, at a location within the second region.
  • the impact printer 10 housed within a cover set includes relatively few moving parts.
  • Vertically-upstanding left-and right-side support plates 14 and 16 are each secured to the base 12 and support the ends of platen 18 in seats therein.
  • the platen is driven by a suitable motor (not shown) through a gear train including driving gear 20 and driven gear 22 on the platen shaft 24.
  • the side plates also support the ends of a highly-polished guide rod 26 and the ends of reaction bar 28 having an accurately-machined guiding edge 30 facing the platen.
  • the reaction bar is mounted so as to be capable of adjustment in order to maintain the guiding edge 30 parallel to the platen surface and to establish accurately its distance from the platen.
  • a printer carriage 32 comprised of carriage frame plates 34 and 36, each having a bearing 38 mounted thereon, is supported upon the guide rod 26 for reciprocating movement therealong, across the length of the platen.
  • Carriage reciprocation is controlled by a motor (not shown) which drives a toothed spacing belt 40 (a cable or rack drive may be used instead) secured to the carriage, over pulleys 42 and 44.
  • a motor not shown
  • a toothed spacing belt 40 a cable or rack drive may be used instead
  • the shoe is made of a hard, low-friction material.
  • This carriage mounting arrangement facilitates inexpensive assembly of the printing device because it eliminates criticality in the placement of the guide rod, requiring only one element, the reaction bar 28, to be accurately positioned.
  • the guiding edge 30 may be accurately positioned parallel to the platen, so that as the carriage 32 traverses the printer, all the printing elements carried thereon will remain in their proper position relative to the platen.
  • the printing elements comprise a printwheel 50, a hammer assembly 52 and a ribbon pack assembly 54 (seen in Figure 3).
  • a printwheel drive motor 56 mounted on the carriage frame plates 34 and 36 has a drive coupling 58 to which a printwheel hub 60 may be connected for rotation of the character pads 62 (located at the ends of printwheel spokes 64) past a print station adjacent to the platen. Selective rotation of the drive motor 56 under processor control, initiated by keystrokes, locates and arrests the desired character pad 62 at the print station.
  • a resilient card guide 66 also mounted on the carriage frame plates holds an image receptor sheet 68 in intimate contact with the platen surface.
  • the hammer assembly 52 is best seen in Figures 3 and 4, wherein carriage frame plate 36 has been cut away to reveal it better.
  • a hammer-actuating DC motor 70 is mounted upon carriage frame plate 34, with its drive shaft 72 extending through and beyond both frame plates.
  • Hammer drive cam 74 secured to the shaft 72 moves cam follower 76 to rotate bell crank 78 about pivot pin 80.
  • the hammer 82 is pinned at the opposite end of the bell crank and slides through a stationary guide bearing 84.
  • As the motor rotates it also drives timing disc 86 relative to a fixed sensor 88 for generating a location count in motor controller 90, mounted upon circuit board 92.
  • the circuit board is illustrated as being secured to the carriage, it is possible to mount it on the base.
  • the motor controller sends signals to the DC motor for effecting cam rotation at a desired speed and in a desired direction.
  • the hammer in order to achieve low impact noise, the hammer must initiate contact at a very low speed (under 400 mm per second), but in order to achieve a satisfactory printing speed, it must move rapidly across the throat.
  • These movement characteristics are determined by the profile of hammer drive cam 74 and the DC motor rotational speed as determined by the controller 90.
  • a representation of the cam displacement characteristics can be seen in Figure 5.
  • a first cam region 74a will result in the illustrated rapid hammer displacement, in which harmonic motion has been selected to move the hammer smoothly for minimizing acoustic noise associated with cam transition points and for reducing cam and cam follower wear.
  • a second, linear, cam region 74b will result in the shallow straight line displacement (e.g.
  • the print force is resolved as the hammer 82 is driven against the platen and the shoe 46 is driven against the reaction bar 28.
  • the print force and the reaction force would be equal and opposite and no other system elements would experience any force at impact.
  • it is often not possible to align these forces in which case there will be a force through the carriage and other elements of the system, including the guide rod 26, all of which should be as low as possible.
  • the efficiency of the quiet impact printing method can be improved by impacting the platen with the hammer approaching at various approach speeds, in accordance with the size of the character to be printed.
  • the former method is less efficient, because it requires the motor to accelerate the large hammer mass and then to decelerate it solely to traverse the throat distance, but it is slightly quieter in operation.
  • the contact speed is relatively low (i.e. less than 400 mm/s, the present invention will result in a controlled low-frequency impact.
  • the effective hammer mass at the moment of impact must be greater than 0.25 kg, and the platen deformation period greater than 1 millisecond.
  • the present invention eliminates the need for hard forward and reverse driving of the DC motor, for moving the hammer tip across the throat distance, it requires significantly lower power.
  • the motor drives the hammer tip to achieve a desired speed (and maintain it) just prior to impact with the platen.
  • Curve A represents the speed response for characters needing the highest energy level
  • curve B represents the speed response for the most-frequently used impact levels (i.e. the "x" and similar characters).
  • the target speed for these high energy curves is achieved and maintained prior to the initiation of the impact zone (i.e. the location at which impact may be expected).
  • the system is slowed down from curve B to the desired lower target speed at one or more predetermined points.
  • the alternative of accelerating the system from the starting point directly to the C and D target speeds is not efficient for these low energy levels since it would significantly extend the print cycle time.
  • an optical encoder assembly is incorporated from which position, speed and direction may be determined.
  • Such an interruptive encoder assembly may comprise a radially-slotted timing disc, mounted upon the motor drive shaft, and a sophisticated IC sensor mounted in a housing positioned relative to the disc. The sensor typically employs a single light source (e.g.
  • a light-emitting diode a light-emitting diode
  • two accurately positioned photodetectors and logic circuitry which provides two outputs: a counting pulse generated whenever the illumination level on one of the photodiodes passes through a threshold level, and a direction output which is set in response to which of the two channels is illuminated first.
  • a dual channel sensor Such a device is referred to as a dual channel sensor.
  • a simple sensor is typically used in systems where the controller is using the output information for counting, determining speed, and/or detecting a stop position.
  • Such a sensor (referred to as a single channel sensor) employing a single light source and a single detector will not yield direction information.
  • These systems often use an interrupting timing disc with a unique location feature such as a flag, or wide slot (for use in a transmissive mode), or a wide reflective element (for use in a reflective mode), whose width dimension is a multiple (such as 3x) of the width of the remaining circumferential interrupting features (narrow slots or reflective stripes).
  • the flag may be easily detected and differentiated by a controller.
  • the location feature is usually phased with a desired stopping position of the mechanism.
  • timing disc 86 having radial interrupting features (narrow slots) 94 and flag (wide slot, comparable to three narrow slots) 96 movable past the fixed simple sensor 88.
  • the flag is placed relative to the cam at a location intermediate the motion end points, where the rotational speed is expected to be substantially constant and the direction of movement is known.
  • FIG. 7 there is illustrated a state diagram showing the programmed print cycle as used in the present invention with a simple sensor, and employing variable impact speed for achieving low-cost quiet impact printing.
  • the program performs the following series of routines, wherein exemplary values for times and location are set forth:
  • a look-up table in the controller 90 is used to determine the desired impact energy (speed) for the character to be printed. As shown in Table 1 and Figure 5, four impact speed classes have been selected. It is certainly possible to assign more, if needed. From the curve of Figure 5, it can be seen that, starting from a home position, an initial target speed is selected. For high-energy characters (curves A and B) the impact speed will be the initial target speed. For low-energy characters (curves C and D) the lower impact speed would be too low to be used for traversing the throat, so the initial target speed will be the higher speed of curve B.
  • BEGIN MOVING a high forward drive along either curve A or B is initiated.
  • an initialization loop is implemented. This is done by setting an initial target location equal to the present location plus three counts, and then driving forward until the initial target location is reached. Then the program starts looking for the flag. As the timing disc rotates, a counter is incremented at each interrupt ion of the sensor.
  • the program In LOOK FOR FLAG, the program enables a detect-flag routine which monitors the time between slots, and establishes in memory a flag-present time when a slot time value is greater than twice the time value between the prior two slots (i.e. T F >>T S ). After enabling this routine, the program continues to monitor the speed of the motor as determined by the time it takes between slots (T S ).
  • a drive/coast loop subroutine allows the initial target spped to be achieved. If the present speed is slower than the initial target speed (set at the start), the motor is instructed to drive, and if the present speed is faster than the initial target speed the motor is allowed to coast.
  • the location counter is RESET to a predetermined value depending upon the direction of rotation of the motor, and taking into consideration the missed counts attributable to the wide slot.
  • count 161 is used when advancing to the platen, and count 166 when retreating from the platen.
  • the existence of the flag will disrupt the speed determination because, when the 2x slot time is detected, it could be interpreted as a slowing of the motor and the controller would attempt to drive the motor hard to bring it back up to speed. Instead, the program continues to drive the motor at the same state as immediately prior to the flag being detected until several post-flag sensor interrupts occur and the speed data can again be used.
  • the character to be printed is tested to determine if it is a low-energy or a high-energy character. (a) If the character is a high-energy character (curves A or B), the speed is tested to determine if it is faster or slower than its target value. If it is faster, low current reverse drive and dynamic braking are used until the correct impact speed is achieved. If the speed is equal to or slower than the target speed the drive/coast loop is effected until the impact zone.
  • the hammer In AT IMPACT ZONE, the hammer will be in the drive/coast loop at the target speed.
  • the value of the low drive current is chosen such that it is adequate to maintain the speed, unless the hammer motion is reduced by IMPACT, which is assumed to have occurred when the hammer speed drops to half the target speed.
  • the hammer is put into a coast state and allowed to remain in that state for 5 milliseconds to allow it to continue its forward progress and begin to rebound. Then the hammer is retracted toward its home position.
  • START RETRACT the program begins retracting the hammer with a low reverse drive for 3 milliseconds in order to get the hammer moving.
  • this routine is needed only with low-energy characters because the high-energy characters have a high enough rebound speed.
  • ENDING CYCLE at a predetermined location a two-step deceleration routine is used to bring the hammer to rest. First, a low current forward drive rapidly slows it until the time between slots is greater than 2 milliseconds, then dynamic braking completely stops the motion, as indicated by the time between slots being greater than 5 milliseconds.
  • the target speed is maintained substantially all the way from the reset point to the platen surface.
  • a transition point at which deceleration is initiated, is selected some number of counts after the RESET point. It is important to reduce the time spent at the low target speed because the low speed affects print speed adversely. Optimally, it is desired to achieve the correct target speed just in time. Therefore, the program constantly updates in memory the count at which impact is sensed and how long it took to decelerate to the predetermined impact speed. In this way, the transition point may be adjusted based upon performance of the preceding cycle.

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  • Accessory Devices And Overall Control Thereof (AREA)
  • Dot-Matrix Printers And Others (AREA)
  • Handling Of Sheets (AREA)

Claims (10)

  1. Imprimante à impact (10) constituée d'un rouleau (18), d'un chariot (32) monté pour effectuer un déplacement en va-et-vient généralement parallèle à l'axe du rouleau, un élément d'impression possédant la faculté d'être entraîné en rotation (50) comportant des parties d'impression de caractère disposées sur sa surface, aux caractères étant affectée une désignation de classe selon leur surface d'impression, un sélecteur d'élément d'impression destiné à déplacer l'élément d'impression pour positionner une partie de caractère sélectionnée à un emplacement d'impression, un marteau (82) servant à entraîner les parties de caractère pour déformer le rouleau et un moyen servant à entraîner le marteau en le rapprochant et en l'éloignant du rouleau, le chariot supportant l'élément d'impression, le sélecteur, le marteau et le moyen d'entraînement,
       un moyen servant à affecter des vitesses d'impact différentes au marteau en concordance avec les désignations de classe des parties de caractère,
       un moyen (90) servant à faire varier la vitesse du marteau lorsque celui-ci est déplacé d'une position de repos à une position d'impact, d'une manière telle que le marteau se déplace initialement à travers les premières régions dans lesquelles il se déplace à une vitesse croissante et se déplace ultérieurement à travers une seconde région dans laquelle il se déplace à une vitesse sensiblement constante, et
       un moyen servant à commander l'arrivée aux vitesses d'impact, incluant un moyen servant à incrémenter un compteur périodiquement en réponse au déplacement du marteau en vue de déterminer l'emplacement et la vitesse instantanée du marteau et un moyen servant à réinitialiser le compteur avec un compte prédéterminé, ne tenant pas compte du compte actuel, à un emplacement situé à l'intérieur de la seconde région.
  2. Imprimante selon la revendication 1, dans laquelle le marteau possédant une masse efficace d'au moins 0,25 kg et une vitesse d'impact ne dépassant pas 400 m par seconde à l'emplacement où la partie de caractère déforme initialement le rouleau et dans laquelle la partie de caractère déforme le rouleau pendant une durée de contact d'au moins une milliseconde.
  3. Imprimante selon la revendication 1 ou 2, dans laquelle le moyen de commande comprend un émetteur et un collecteur de signal (88) ainsi qu'un interrupteur de signal (86).
  4. Imprimante selon la revendication 3, dans laquelle l'émetteur et le collecteur de signal comprennent un capteur à simple canal.
  5. Imprimante selon l'une quelconque des revendications précédentes, dans laquelle le moyen d'entraînement comprend un moteur (70) comportant un arbre d'entraînement (72), le moyen servant à faire varier la vitesse du marteau comprenant une came (74) montée sur l'arbre d'entraînement et comprenant une première partie destinée à déplacer le marteau à travers la première région à une seconde partie destinée à déplacer le marteau à travers la seconde région et dans laquelle l'interrupteur de signal comprend un disque de synchronisation (86) monté sur l'arbre d'entraînement.
  6. Imprimante selon la revendication 5, dans laquelle le disque de synchronisation comporte une rangée annulaire de fentes étroites situées au voisinage de son pourtour, dans laquelle se trouve une fente unique dans la rangée qui est sensiblement plus large que les fentes étroites, la fente large et le capteur étant situés par rapport à la came d'une manière telle que la fente large soit détectée après que le marteau ait pénétré dans la seconde région dans son trajet vers le rouleau.
  7. Imprimante selon l'une quelconque des revendications précédentes, dans laquelle le moyen servant à réinitialiser le compteur est actionné lorsque le marteau se rapproche du rouleau et lorsque le marteau quitte celui-ci.
  8. Procédé d'impression à impact, comprenant les étapes consistant à déplacer un élément d'impression possédant la faculté d'être entraîné en rotation (50) comportant des parties d'impression de caractère disposées sur sa surface au-delà d'une zone d'impression adjacente au rouleau (18), arrêter une partie d'impression de caractère sélectionné au niveau de la zone d'impression, déplacer un marteau (88) pour le rapprocher et l'éloigner du rouleau en vue d'entraîner la partie d'impression du caractère sélectionné à déformer le rouleau avec une force d'impression,
       affecter une désignation de classe à chaque partie d'impression de caractère conformément à sa surface d'impression ,
       effectuer différentes vitesses d'impact au marteau en concordance avec les désignations de classe,
       faire varier la vitesse du marteau lorsqu'il se déplace d'une position de repos à une position d'impact en déplaçant rapidement d'une manière initiale le marteau à travers une première région à une vitesse croissante et en déplaçant ensuite le marteau à travers une seconde région à une vitesse sensiblement constante, et
       commander l'arrivée aux vitesses d'impact en incrémentant un compteur périodiquement lorsque le marteau est déplacé et déterminer l'emplacement et la vitesse instantanée du marteau à partir du compte et réinitialiser le compteur avec un comptage prédéterminé, ne tenant pas compte du compte actuel à un emplacement situé à l'intérieur de la seconde région.
  9. Procédé selon la revendication 8, dans lequel l'étape consistant à faire varier la vitesse du marteau comprend en outre l'étape consistant à obtenir la vitesse d'impact et à la maintenir jusqu'à ce que le marteau heurte le rouleau.
  10. Procédé selon la revendication 8, dans lequel l'étape consistant à faire varier la vitesse du marteau comprend en outre les étapes consistant à diminuer la vitesse de celui-ci jusqu'à la vitesse d'impact, après l'étape de réinitialisation et à maintenir la vitesse d'impact jusqu'à ce que le marteau heurte le rouleau.
EP19910311480 1990-12-11 1991-12-10 Imprimantes à impact Expired - Lifetime EP0490643B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US62556990A 1990-12-11 1990-12-11
US625569 1990-12-11

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EP0490643A2 EP0490643A2 (fr) 1992-06-17
EP0490643A3 EP0490643A3 (en) 1992-10-21
EP0490643B1 true EP0490643B1 (fr) 1995-07-19

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EP19910311480 Expired - Lifetime EP0490643B1 (fr) 1990-12-11 1991-12-10 Imprimantes à impact

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EP (1) EP0490643B1 (fr)
JP (1) JPH0798405B2 (fr)
CA (1) CA2051571A1 (fr)
DE (1) DE69111395T2 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3503674B2 (ja) * 1996-09-19 2004-03-08 日立プリンティングソリューションズ株式会社 印刷装置の印刷密度制限装置及び印刷密度制限方法
JP2000052599A (ja) * 1998-08-11 2000-02-22 Hitachi Koki Co Ltd 印刷装置のシャトル制御方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7604474A (en) * 1976-04-27 1977-10-31 Tealtronic Nederland B V Electric typewriter hammer driving mechanism - has coil supplied with pulses fixed to hammer tip working in magnetic field
US4353656A (en) * 1980-10-14 1982-10-12 Xerox Corporation Moving coil, multiple energy print hammer system including a closed loop servo
JPS61141574A (ja) * 1984-12-14 1986-06-28 Sharp Corp 印字押圧力制御装置
SE8802426L (sv) * 1987-10-31 1989-05-01 Triumph Adler Ag Anordning foer avtryckning av paa en summatypsbaerare anordnade skrivtecken

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Publication number Publication date
EP0490643A2 (fr) 1992-06-17
CA2051571A1 (fr) 1992-06-12
DE69111395T2 (de) 1996-03-21
JPH0798405B2 (ja) 1995-10-25
EP0490643A3 (en) 1992-10-21
DE69111395D1 (de) 1995-08-24
JPH04292965A (ja) 1992-10-16

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