WO1985005076A1

WO1985005076A1 - Drive system for different functions in typewriters or printing machines of similar design, based on the use of an electric motor

Info

Publication number: WO1985005076A1
Application number: PCT/DE1985/000126
Authority: WO
Inventors: Albert Rix; Heinz Lange
Original assignee: Olympia Werke Ag
Priority date: 1984-05-02
Filing date: 1985-04-19
Publication date: 1985-11-21
Also published as: EP0181876A1; DE3563931D1; JPS61502047A; EP0181876B1

Abstract

In typewriters and similar machines, in order to perform several functions use is made, for example, of either a separate drive element for each function or of a common drive motor. A change of functions in a common drive motor, in the existing state of the art, is possible by reversing the rotation direction of the motor or by operating an intermediate clutch. The purpose of the invention is to create a common drive device for different functions in typewriters or similar office machines which is less costly and offers a simple and compact design. This problem is solved by the fact that the stator (17) and the rotor (11) of a stepping motor (12) can be operated and locked alternatively for the transmission of the energy supplied by the motor (12) to a first or a second drive mechanism. Since the stator and rotor (11) of the same stepping motor (12) can drive different functions, an inexpensive drive system can be produced.

Description

Drive device for different functions in typewriters or printing devices of a similar design using an electric motor

The invention relates to a drive device for different functions in typewriters or printing devices of a similar design using an electric motor of the type specified in the preamble of claim 1.

For typewriters or similar office machines. is it z. For example, it is known to use either a separate drive element or a common drive motor for several drive functions. The state of the art makes it possible to change the function of a common drive motor by reversing the direction of rotation of the drive motor or by actuating intermediate clutches. A drive device is known from EP-OS 0 038 215, in which a reversibly drivable stepper motor can perform two different functions in an office machine, depending on its direction of rotation. After the first function has expired, the second function can only take place after the direction of rotation of the stepping motor has been reversed. Time losses occur for two functions to be performed immediately one after the other, such as thermal printhead lifting from the recording medium and its transport in the line direction. In addition, a complex circuit arrangement is required for this.

A thermal writing mechanism is known from DE-PS 24 06 613, in which a stepping motor is provided for the transport of the recording medium and an electromagnet is provided for pressing and lifting the thermal print head from the recording medium. This makes the writing mechanism relatively complicated and expensive to manufacture. The invention has for its object to provide a common drive device for different functions in power-driven machines, in writing or printing devices of a similar design using an electric motor, which is inexpensive and enables a simple and space-saving design. This object is achieved by the invention specified in the characterizing part of patent claim 1.

Since different functions can be driven via the stator and the rotor of the same stepping motor, an inexpensive drive device is created. By alternately locking the stator and the rotor of the stepping motor, a first or a second drive device can either run either at the beginning of the flow of the stepping motor or immediately one after the other.

Due to the advantageous embodiment of the subject matter of the invention, a third and a fourth function can be driven further. The stator and the rotor can be locked by one locking device each. Thus, after energization of the motor, the stator can be pivoted from a starting position into a latchable end position for driving a first drive device, after which, after being blocked in the end position, the drive movement of the rotor starts to drive a second drive device. It is also possible that first the rotor and then the stator are set in rotation.

By a further embodiment of the subject matter of claim 8, a separate locking device z. B. omitted for the rotor. In this case it is necessary that the moments of inertia of the drive devices to be driven in one direction of rotation of the stepper motor are different, such that the rotary movement of the rotor starts automatically after the stator is locked. This further simplifies the drive device. Further advantageous features of the invention are characterized in the subclaims. The invention is illustrated in the drawings using exemplary embodiments and is explained in more detail below. It shows

FIG. 1 shows a schematic illustration of the thermal printer in a side view,

FIG. 2 shows a plan view of some parts essential to the invention according to FIG. 1,

3 shows a side view of a second embodiment and

Figure 4 is a side view of an advantageous embodiment of the subject matter of the invention.

In Figures 1 and 2, for. B. is shown a drive device for a thermal printer with a transport roller 1 for a heat-sensitive recording medium 2, which can be brought into contact with pressure in a known manner for generating records with a thermal print head 3. This thermal print head 3 has thermally insulated areas or dots which are arranged in the form of a matrix, so that an electrical signal for driving one of these matrix dots can be applied, as a result of which the driven matrix dot is heated. The thermal print head 3 is fastened on a carrier 4, on which a cable 5 for supplying a signal for driving the matrix points of the thermal print head 3 is fixedly arranged.

On an axis 7 of the transport roller 1, a gear 6 is fastened on one side, which meshes with an intermediate gear 8. This intermediate gear 8 is with a drive wheel 9 firmly connected, which can be driven by a pinion 10. This pinion 10 is fastened to the rotor 11 of a stepping motor 12, the rotor 11 being rotatably mounted in bearings 15, 16 arranged on both sides of the motor 12 in side walls 13, 14. A control element 18 is fixedly connected to the stator 17 of the stepping motor 12 and has a latching recess 19 and control cams 21, 22 symmetrical to this (19), see FIG. 1. In addition, the control element 18 has stop edges 23, 24 Provided, which are limitable to limit the pivoting movement of the stator 17 on the rotor 11 with frame-fixed stops 25, 26 for contact. The stop edges 23, 24 consist of flexible webs 27, 28 for the purpose of adjustment, which recesses 29, 30 for engagement of an adjusting tool, for. B. a commercially available screwdriver. As a result, the pivoting movement of the stator 17 from a central position can be set exactly in the simplest way in both directions of rotation. A latching nose 31 of a slide 20 spring-loaded by a spring 32 can be latched into the latching recess 19 and is slidably mounted on guide bolts 34, 35 by means of an elongated hole 33. The spring 32 is articulated on the one hand with the guide pin 34 and on the other hand on a pressure rocker arm 36 such that a stop edge 37 on the print head release arm 36 always rests non-positively on a stop lug 38 of the slide 20 and the slide 20 in the direction of arrow 39 acted upon. The printhead release rocker 36 is pivotally mounted about an axis 40 fixed to the frame and has a rail 41 arranged in the row direction. This slide 41 can be brought into contact with a stop arm 42 of the carrier 4 with the thermal print head 3 for releasing this thermal print head 3. Incidentally, the carrier 4 is displaceable in the line direction on a guide axis 43 arranged parallel to the transport roller and is pivotably mounted about this (43) against the force of a spring 44. To release the thermal print head 3 from the recording medium 2 during the non-printing relative movements between the thermal printing head 3 and the recording medium 1, the stepping motor 12 is actuated by a control element, not shown, e.g. B. controlled and energized by a microprocessor in the desired direction of rotation. Due to the inertia of the transmission members 9, 8, 6, which are operatively connected to the pinion 10 of the stepping motor 12, and the transport roller 1, the stator 17 is first pivoted about the rotor 11. As a result of the now rotating movement of the stator 17, the slide 20 is displaced via one of the control cams 21, 22 in the opposite direction of the arrow 39, the print head release rocker 36 being pivoted about the axis 40 in the counterclockwise direction. As a result, the stop arm 42 of the carrier 4 is pivoted clockwise about the axis 43 via the rail 41. The thermal print head 3 detaches from the recording medium 2 so that no wear of the thermal print head 3 can occur during the above-mentioned non-printing relative movements. The pivotal movement of the stator 17 is limited clockwise by hitting the stop edge 24 against the stop 26 and counterclockwise by hitting the stop edge 23 against the stop 25. After blocking the pivoting movement of the stator 17, the rotor 11 begins to rotate, whereby the transport roller 1 for transporting the recording medium 2 is rotated in the line feed or line return direction via the gear pairs 10/9 and 8/6. During these rotary movements of the rotor 11, the slide 20 is locked via the cam sections 45 and 46, respectively, and thus the print head release rocker 36 and the carrier 24 are held in the pivoted position. After the desired transport of the recording medium 2, the direction of rotation of the stepper motor 12 is reversed, this stepper motor 12 receiving so many drive impulses that the slider 20 can snap resiliently into the catch recess 19 of the control element 18 with its catch 31. The printhead release speeds are ge 36 and the carrier 24 returned to their working positions. The thermal print head 3 is now again in pressure contact with the recording medium 2. When the above-mentioned energization of the stepping motor in the reverse direction of rotation, the rotor 11 stops again, the stator 17 being pivoted back into the central position alone.

Within the scope of the invention, it is also possible for the control element 18 to be automatically returned to the latchable central position after the stepper motor 12 has been de-energized by the sprung (22) slide 20. Here, the control cams 50, 51 must have a shape according to FIG. 3 such that the slide 20 cannot be locked in the end positions of the stator 17 via the control cams 50, 51. Here, after the transport of the recording medium, there is no need to actuate the stepping motor 12 again. B. by the microprocessor.

4, two oppositely toothed gear wheels 52, 53 can also be firmly connected to the rotor 11, with the toothings 54, 55 of which pawls 56, 57 engage. The pawls 56, 57 are pivotable on both sides of the rotor 11 about fixed axes 58, 59, by a common spring 60 with their locking teeth 61, 62 in engagement with the teeth 54, 55 of the locking gears 52, 53 - And by a pivotable with the stator 12 stop 63 out of engagement with the ratchet gears 52, 53. This reliably prevents the rotor from transmitting a rotary movement to the transport roller 1 via the intermediate gearwheels only when the stator 17 has reached one of the end positions. A rotary movement of the rotor 11 is only possible when one of the pawls 56, 57 has been disengaged from the teeth 54, 55 of the ratchet gears 52, 53.

The thermal printer according to the invention is characterized by a simple and inexpensive construction, with a long service life the thermal print head is guaranteed. It can also be used advantageously if characters are generated on plain paper with the interposition of a heat-sensitive ink ribbon.

Within the scope of the invention, the most varied functions in power-driven machines in all technical fields can be driven in the simplest way with the subject matter of the invention.

Claims

Claims:

1. Drive device for different functions in typewriters or printing devices of a similar design using an electric motor, so that the stator (17) and rotor (11) of the electric motor are freely rotatable and with different drive devices are in operative connection.

2. Drive device according to claim 1, characterized geken n ¬ ze i chnet that the electric motor is reversibly driven.

3. Drive device according to claim 1, characterized by the fact that the rotation of the stator (17) and / or of the rotor is fixed by a locking device.

4. Drive device according to claim 1 with a step-by-step motor, the rotor of which is connected to a transport roller for the transport of a record carrier and the stator of which releases and presses a thermal print head, characterized in that the moment of inertia of the transport of the Recording carrier effecting drive device is so large that when the motor is energized, the stator first rotates.

5. Drive device according to claim 4, characterized by the fact that the frame-fixed stops (25, 26) are provided which project into the web of webs (27, 28) fastened to the stator (17).

6. A printer according to claim 5, wherein the print head is arranged on a slide which can be displaced in line forward and line return directions on a guide axis since ¬ du rc hgeennzeichn et that the stator (17) is a control element (18) with a latching recess ( 19) for a sprung slider (20) that the control element (18) has control cams (21, 22) on both sides of the latching recess (19), through which the slider (20) for adjusting a print head release rocker (20) when the stator (17) is pivoted. 36) for the print head (3).

7. Printer according to claim 6, dadu rc h ge ken nzeich ¬ net that the printhead release rocker (36) has a in the row direction arranged rail (41) with a stop arm (42) on the pivotable printhead (3) for releasing it can be brought into operative connection.

8. Printhead according to one of the preceding claims, that a ¬ du rc h g e ke n nz e i c hn et that on the slide (20) engages a return spring (32) which urges it against the control element (18).

9. Printhead according to one of the preceding claims, since ¬ d urc h geke nn ze ichn et that with the rotor (11) two oppositely toothed ratchet gears (52, 53) are firmly connected, in their teeth (54, 55) pawls ( 56, 57), and that the pawls (56, 57) for transporting the recording medium (2) can be brought out of engagement alternately depending on the transport direction.

10. printhead according to claim 9, d ad u rc h ge ken nzeich ¬ net that the pawl (56, 57) on both sides of the rotor (11) about frame-fixed axes (58, 59) swivel, by a common spring (60) with their locking teeth (61, 62) in engagement with the toothing (54, 55) of the locking gearwheels (52, 53) and by a stator (17) pivotable stop (63) out of engagement with the locking gearwheels (52 , 53) can be brought.