IBM Selectric typewriter
As typewriters ball head ( rare: Type Head ) refers to a type - carrier of a particular type in electromechanical typewriters. The characters to be written on the other are arranged in a plurality of circles located on the periphery of a spherical ring. To select a character, the head is rotated about the ring axis, and in addition tipped. Each button triggers the selection of movements for its corresponding type. To print the very light ball head against the platen with the clamped paper and the overlying ribbon is struck.
Was introduced in the IBM Selectric ball head typewriter on 31 July 1961.
Demarcation from other type carriers
The ball head is an all used types containing type carrier. He was from the short cylinder type used by Blickensderfer in 1893 (then called daisy wheel ) designed for 1961 presented by IBM typewriter. To select the desired type, rotation and vertical displacement, the ball rotation and tilting are ( some authors called tilt) and the modern type wheel rotation only necessary when type cylinder. These three type carriers have the advantage that they can be easily replaced to allow the change to a different font compared to type levers on typewriter type lever - for example, for writing special characters. That a " secretary's Dream" (IBM - advertising) came true, because the Fast Typing hooked no more type lever, nothing was entirely new. This dream had been out in the Blickensderfer already met in other older, but slower typewriters compact type carriers.
IBM typewriters with Ball Head
A further improvement in the IBM typewriters ball was that the ball head held lighter of the platen roller is moved in the row direction. The ball head but was ultimately replaced by modern daisy wheel, whose only rotational motion could be generated from entrained in the row direction light electric motor. The elaborate mechanisms for rotating and tilting the ball head accounted for. The type wheel was lighter than a ball head, which also contributed to the even faster writing or printing in conjunction with word processor and text systems.
Function of an IBM ball head
The printing type are arranged on four groups on the surface of the spherical ring - comparable width circuits on the globe. By tilting the head about an axis parallel to the platen leading through the ball center axis of the circle is selected at the desired print type. By turning around the globe axis the desired type is determined within this circle, she now has the correct position near the point of impact on the paper. Types on a circle lying adjacent are offset in a maximum of 20 types for each circuit by a rotation angle of 18 °; then instead of 80 possible types also have spherical heads with 88 (see photo above: ball head with 22 tines ) were with IBM and 96 types in the program, which smaller angle of rotation due. The achievable using the Shift key ( Shift) type is each offset by 180 ° on the same circle. The operation of the first shift causing a half-turn of the ball head, the rotation corresponding to the selected type, follows. To minimize the rotational movements are frequently used types arranged close to each other.
In the cap of the replaceable ball head is the locking mechanism including handles. At the bottom of a jagged rim is used for fine adjustment after the rotation around the axis ball head. An IBM - ball head has an overall height of 27 mm (Pip lace up cap ) and an outer diameter of about 35 mm and weighs 10.2 g
Drive the ball head in IBM typewriters
The car with the platen roller and clamped writing sheet moves horizontally in most typewriters to the next writing position - within the same line - to achieve, so when IBM ball typewriters remains the roll paper stand, and the ball head is in front of the blade to the desired position pushed. For this purpose, it is mounted on a carriage which is driven by a motor back and forth across a tightrope. To select the desired printing type, the ball head must be rotated and tilted accordingly, and to trigger the write operation, are suddenly pressed against the platen. All these movements are caused by a single electric motor mounted in the machine frame after approval by the appropriate keystroke.
The ball head carriage with a wire traction mechanism, in which one run it is attached is reciprocated. The ball head rotations are produced by means of movements in two further Zugmittelgetrieben a respective pulley. The wire ropes from this co-moving ball head carriage gears are cut. One of the rope ends are each fixed to the carriage and the other attached to a lever, which causes the corresponding rotation of ball head on the slide. By the deflection of a pulley, the free end of the cable pulls on the lever, and rotates or tilts the ball head corresponding to the selected printing type. The selection process is independent of the instantaneous position of the ball head and the carriage may also take place during carriage movement.
Olivetti
The Olivetti did not pursue on their ball typewriter, which could be built upon expiration of IBM patents, to the elaborate wire gear and stayed with the conventional typewriter carriage with lateral movement of the platen as the prototype locomotive Blickensderfer No. 5
Trivia
In the film, Mademoiselle Populaire co-star Louis invents the ball typewriter.