DD288795A5

DD288795A5 - LINE SWITCHING DEVICE

Info

Publication number: DD288795A5
Application number: DD33425189A
Authority: DD
Inventors: Claus Graichen; Werner Tell; Hans-Juergen Theileis
Original assignee: Veb Robotron-Buchungsmaschinenwerk,De
Priority date: 1989-11-06
Filing date: 1989-11-06
Publication date: 1991-04-11

Abstract

Die Erfindung betrifft eine Zeilenschaltung fuer elektrische Schreib- und aehnliche Maschinen, die sowohl mittels eines motorischen Antriebs als auch mittels eines Handrades erfolgt. Bei derartigen Zeilenschalteinrichtungen musz gewaehrleistet sein, dasz der manuelle Rastvorschub mit dem motorischen Rastvorschub bezueglich des kleinsten Zeilenschaltschrittes uebereinstimmt. Herkoemmliche Mittel wie Rastraeder und in diese einfallende Rastelemente koennen gemaesz der Erfindung entfallen. Dies wird dadurch erreicht, dasz eine Schnecke als Antrieb federnd in ein auf der Schreibwalzenwelle befestigtes Schneckenrad eingreift. Erfolgt eine manuelle Zeilenschaltung ueber ein Handrad, so weicht die Schnecke dem angetriebenen Schneckenrad federnd aus. Neben den Antriebsfunktionen uebernehmen die Schnecke und das Schneckenrad zugleich die bisher bekannte Funktion des Rastelementes bzw. des Rastrades. Figur{Zeilenschalteinrichtung, motorisch, manuell; Schnecke; Schneckenrad; Rastrad; Rastelement; Handrad}The invention relates to a line circuit for electrical writing and similar machines, which takes place both by means of a motor drive and by means of a handwheel. In such line switching devices, it must be ensured that the manual detent feed coincides with the motor detent feed with respect to the smallest line switching step. Herkoemmliche means such as Rastraeder and incident in these locking elements can be omitted gemaesz the invention. This is achieved by a worm as a drive resiliently engages in a fixed to the platen shaft worm wheel. If a manual line feed occurs via a handwheel, the worm deflects the driven worm wheel elastically. In addition to the drive functions take the worm and the worm wheel at the same time the previously known function of the locking element or the ratchet wheel. Figure {Line switching device, motor, manual; Slug; worm; ratchet wheel; Locking element; handwheel}

Description

Erf indung.igemäß wird dies dadurch erreicht, daß die motorische Zeilenschaltung in bekannter Weise über eine Schnecke und ein Schneckenrad erfolgt, wobei jedoch die Schnecke federnd In das Schneckenrad derart eingreift, daß bei manuellem Antrieb mittels eines Handrades die Schnecke dem Schneckenrad federnd ausweicht. Das Schneckenrad und das Handrad sind fest mit der Schroibwalzenwelle verbunden.Erfindung.igemäß this is achieved in that the motor line switching takes place in a known manner via a worm and a worm wheel, but the worm resiliently engages the worm wheel such that when manually driven by a handwheel, the worm resiliently evades the worm wheel. The worm wheel and the hand wheel are firmly connected to the Schroibwalzenwelle.

Ausführungsbelsplol The invention will be described below with reference to an embodiment. The accompanying drawing shows a line switching device in a type plate typewriter.

Ein Handrad 1 und ein Schneckenrad 2 sind fest mit einer Schreibwalzenwelle 3 verbunden. Der motorische Zeilenschaltantrieb erfolgt mittels eines Motors 4, dessen Welle S eine Schnecke β trägt. Die Schnecke β greift federnd in das Schneckenrad 2 ein. Dazu wird der Motor 4 auf einer ortsiu-'en Achse 7 drehbar gelagert, und durch eine an ihm befestigte Feder 8 wird der federnde Andruck der Schnecke 6 an dem Schneckenrad 2 aufrechterhalten. Die Verzahnungsteilung der Schnecke β und des Schneckenrades 2 entspricht der Länge einer halben Zeilenschaltung. Soll nun eine manuelle Zeilenschaltung erfolgen, so wird über das Handrad 1 das Schneckenrad 2 gedreht. Durch die federnde Anlage der Schnecke 6 an dem Schneckenrad 2 werden der Motor 4 und die Schnecke 6 entgegen dem Zug der Feder 8 kurzzeitig im Uhrzeigersinn geschwenkt. Anschließend erfolgt nach dem Loslassen des Handrades 1 wieder eine Schwenkung im Uhrzeigersinn. Für den Bediener sind dabei die Bewegungen der Zahnspitzen des Schneckenrades 2 an den Zahnflanken und über die Zahnspitzen der Schnecke 6 hinweg deutlich zu verspüron. Der Steigungswinkel des Schneckenrades 2 und der der Schnecke 6 wird so gewählt, daß dieser kleiner als der Grenzwinkel ist. Dadurch wird vermieden, daß das auf die Schnecke 6 übertragene Drehmoment zu einer Drehung der Schnecke β führt. Bei der erfindungsgemäßen Lösung übernimmt das Schneckenrad 2 zugleich die Funktion eines herkömmlichen Rastrades, während die Schnecke 6 neben ihrer Antriebsfunktion die Aufgabe eines Rastelementes für das Rastrad ausführt.A hand wheel 1 and a worm wheel 2 are fixedly connected to a platen shaft 3. The motor-driven line switching drive takes place by means of a motor 4 whose shaft S carries a worm β. The worm β resiliently engages the worm wheel 2. For this purpose, the motor 4 is rotatably mounted on a ortsiu -'en axis 7, and by a spring 8 attached to it, the resilient pressure of the screw 6 is maintained on the worm wheel 2. The toothing pitch of the screw β and the worm wheel 2 corresponds to the length of half a line feed. If now a manual line switching take place, the worm wheel 2 is rotated via the handwheel 1. Due to the resilient engagement of the worm 6 on the worm wheel 2, the motor 4 and the worm 6 are briefly pivoted counter to the tension of the spring 8 in the clockwise direction. Subsequently, after releasing the handwheel 1 again a clockwise rotation. For the operator, the movements of the tooth tips of the worm wheel 2 on the tooth flanks and over the tips of the teeth of the worm 6 are clearly to be felt. The pitch angle of the worm wheel 2 and the worm 6 is chosen so that it is smaller than the critical angle. This avoids that the torque transmitted to the worm 6 leads to a rotation of the worm β. In the solution according to the invention, the worm wheel 2 at the same time assumes the function of a conventional ratchet wheel, while the worm 6 carries out the task of a locking element for the ratchet wheel in addition to its drive function.

Claims

Line switching device for electrical writing and similar machines, in which the line switching takes place both by means of a single motor drive and by means of a hand wheel, wherein the motor drive consists of a motor which drives a arranged on a platen shaft worm gear via a worm, and the manual drive via the fixed to the platen shaft connected to the hand wheel, characterized in that the worm wheel (2) is fixedly connected to the platen shaft (3) that the screw (6) resiliently engages the worm wheel (2) such that when manually driven by of the handwheel (1), the worm (6) the spring worm (2) resiliently evades.

For this 1 page drawing

Field of application of the invention

The invention relates to a line switching device for electrical writing and similar machines, in which the line switching takes place both by means of a motor drive and by means of a handwheel.

Characteristic of the known state of the art

In the case of line switching devices for electrical writing and similar machines, the drive for paper transport is effected exclusively by motor or additionally by means of a manual adjusting element in the form of a handwheel. The motor drive is usually carried out by means of a stepper motor, by which a preselected latching feed of the recording medium is effected. This detent feed corresponds to normal writing activity of a 1/2, 1 or 11 / 2zeiligen rotary movement of the platen. If in the course of writing activity by means of the handwheel a line shift performed - this is usually done for the purpose of correction - it must be ensured that the manual detent feed coincides with the motor detent feed with respect to the smallest line switching step. For this purpose, special means are provided in the known writing devices. These means consist of a ratchet wheel and a locking element which engages resiliently in the ratchet wheel. The ratchet wheel is rotatably connected to a platen shaft with the handwheel, the pitch on the ratchet corresponds to a half-line circuit (DE-OS 2943493, DE-AS 2758148, DE-OS 3122985). Dor permanent engagement of the locking element in the ratchet wheel has the disadvantage that when motor drive an additional noise source is produced and that further, the motor must be designed for a higher load. The advantage is only that can be dispensed with due to the mechanical latching to a holding current of the stepping motor. To avoid the disadvantages listed, the solution according to DE-OS 3419271 provides a control that removes the locking element from the ratchet wheel in the motor-driven line switching drive and can come up again after completion of the line switching.

The device according to DE-OS 3407667 avoids the disadvantages described above and an additional control for the release of the locking element. For this purpose, a rotatably mounted on the platen roller shaft worm wheel is provided on the front side of a locking lever is mounted. The detent lever engages resiliently in a ratchet, which is like the handwheel for the line connection firmly connected to the platen shaft. The motor line switching takes place in such a way that the worm wheel is driven by a worm. By the bearing of the locking lever on the worm wheel, the rotational movement of the worm wheel is transmitted to the ratchet wheel and thus to the platen shaft. In the manual line switching via the handwheel, only the ratchet wheel rotates, wherein the locking lever after releasing the handwheel fixed the rotational position of the ratchet wheel and thus also the platen shaft. Since the pitch angle of the worm wheel and that of the worm is set smaller than the critical angle, a torque transmitted from the worm wheel to the worm does not cause rotation of the worm connected to the motor.

The described line circuit thus also requires to bypass the mentioned disadvantages also a ratchet wheel, a locking lever with associated spring and an axial securing for the loose on the platen roller shaft worm wheel.

Object of the invention

The invention aims at a reduction of the partial expenditure.

Explanation of the essence of the invention

The invention has for its object to develop a line! Switching device for electric typewriters, in which the line switching takes place both by means of a motor drive and by means of a handwheel, wherein with respect to the smallest line switching step of the manual line switching step with the motor line switching step in such a match is that this requires no special additional means such as a ratchet wheel and an associated locking element.