FR2622509A1 - HAMMER PRINTING DEVICE HITTING A CHARACTER SUPPORT - Google Patents

Abstract

Device for printing, by means of a hammer capable of being actuated by means of an electric motor, writing characters arranged on a character support. The motor 7 acts, in on-off operating mode, on a cam 9 which exerts, on a pivoting hammer 10 subjected to the action of a spring 12, a driving action such that this hammer strikes in free flight the character 4 to print. The power supply to the motor is advantageously differentiated in order to obtain different printing forces.

Description

2i2509 The invention relates to a device for printing, by means of a

  hammer can be operated by means of an electric motor,

  writing characters arranged on a character carrier.

  In particular in typewriters with a printing wheel, it is known that the writing characters arranged on the spokes of the printing wheel are caused to perform printing by means of an intermediate member, after having been placed in the printing position, said intermediate member being driven by an electric motor. For example, German patent application DE-OS 27 17 975 shows an eccentric actuated pusher, cooperating with the spokes of the printing wheel. In this case, when the machine is supplied with current, the eccentric rotates constantly, so that the pusher performs a continuous back and forth. A complicated and therefore expensive synchronization device is necessary to avoid execution

unwanted impressions.

  German patent applications DE-AS 18 07 387 and DE-OS 21 01 995 represent and describe other motor-driven printing devices. In these cases, additional controls are required to allow the proper printing of a selected character. In one case, it is an oscillating rod which cooperates with selection levers and, in the other case, a magnet which drives a corner between the eccentric and the selected character. These additional control mechanisms are also expensive and complicated. In addition, known devices do not offer any possibility of causing the printing force to act in a differentiated manner as a function of the surface of the sign or character printed. It is therefore doubtful that one can obtain a writing having a beautiful appearance with these known devices. Even more, there is reason to expect uneven prints because all the characters are printed with the same energy, regardless of what they have

a large or a small area.

  The object of the invention is to produce a device of the type indicated at the start, for typewriters or printers, so that there is no need for any additional control member or synchronization device. In addition, this goal must be achieved so that the characters coming to the printing are printed with energy.

  corresponding to the surface of the writing sign considered.

  To achieve the first object mentioned, the invention provides, in the case of a device of the type mentioned at the beginning, that the motor acts, in operating mode on / off, on a cam which exerts, on a pivoting hammer subjected to the action of a spring, a driving action such as this hammer strikes in free flight the

character to print.

  As the motor acts on the printing hammer while operating in start-stop mode, it is not necessary to order additional intermediate members. As a result, the motor rotates the cam 360 'for each print, so that the hammer can, by acting in free flight, cause

  printing the symbol positioned for this.

  In order to obtain regular writing, the invention recommends that the motor be supplied in a differentiated manner in order to obtain different printing forces. In other words, the engine is powered differently depending on the character presented to the print. In this case, the individual types of power supply can be read automatically from a memory and transmitted to the motor. Thus, for example to obtain a weaker impression, such as that necessary for the point or the comma, the acceleration chosen may be different from that necessary to print a

  large area letter such as, for example, "t and" "'.

  - The invention provides in particular a stepping motor for

  the printing drive.

  By providing that in its rest position the hammer is applied against a stop, the invention offers this advantage that the bearings of the motor shaft are not constantly subjected to a thrust and that the rebound of the hammer does not affect on the motor shaft. This contributes significantly to the longevity of the device as well

  stabilization of the operating silence.

  The characteristics and advantages of the invention will become apparent

  more fully in the description presented in the following, at

  by way of nonlimiting example, with reference to the appended drawing, the single figure of which schematically represents a side elevation view of the device. In order to preserve the clarity of the drawing, we have omitted

  parts not directly related to the invention proper.

  In front of the cylinder or roller 1 of a typewriter, a printing wheel 3 provided with characters 4 is mounted, in a known manner, on the angular positioning shaft 2. The motor for the angular positioning of the wheel impression 3 is not shown. The motor 7 is fixed on an upright 6 located on a support which can be at the same time a movable carriage along the cylinder 1 of the typewriter. On the shaft 8 of this motor is mounted a cam 9 which can cooperate with a hammer 10. The hammer 10 can pivot

  around an axis 11, and is pulled against a stop 13 by a spring 12.

  For each printing, the motor 7 is supplied with current, so as to rotate the cam 9 by 360. The cam 9 then projects the hammer 10 in the printing direction, by pivoting it around its axis 11, so that that of the characters 4 of the printing wheel 3 which has been placed in position is put into the condition of execution of a printing. Examination of the drawing makes it easy to understand that this device for printing writing characters

  is substantially simpler in structure than known devices.

  This is primarily due to the fact that the motor 7 operates in on-off mode to cause printing. It will also be understood without problem that a differentiated supply of the motor 7 makes it possible to obtain different printing forces for the characters. If the motor 7 is a stepping motor, this can be obtained without difficulty by establishing determined acceleration and braking curves. In the case where the motor 7 must be a direct current motor, it must then be provided with an angle sensor or another suitable device, so as to obtain as differentiated execution of the movements

  lead to different printing forces.

  As the hammer 10 acts in free flight on the spokes of the printing wheel 3, the hammer 10 and the cam 9 can move independently of one another. This applies in particular to movement

  backward movement of the hammer 10 Until it returns to contact with the stop 13.

  Of course, various modifications can be made by those skilled in the art to the devices or methods which have just been described solely by way of non-limiting example, without departing from the

part of the invention.

Claims (4)

CLAIMS:   1. Device for printing, by means. of a hammer which can be actuated with. by means of an electric motor, writing characters arranged on a character support, characterized in that the motor (7) acts, in operating mode on / off, on a cam (9> which exerts, on a pivoting hammer (10) subjected to the action of a spring (12), a driving action such as this hammer   hits the free character (4) to print.   2. Device according to claim 1, characterized in that the electrical supply of the motor is differentiated in order to obtain   different printing forces.   3. Device according to claims 1 and 2, characterized by the   fact that the motor (7) is a stepping motor.   4. Device according to claim 1, characterized in that the hammer (10) is in contact with a stop (13) when it is at its rest position.