Daisy wheel printing

The type wheel (English daisy wheel, literally: Daisy wheel ) is one next to Type levers and ball joint to the most common type carriers of electromechanical typewriters.

General

The typewriter types are all mounted in a plane on resilient radial arms of the type wheel. By rotating the wheel the desired character is placed in position and beaten with an electromagnetically actuated pin against the ribbon and paper. The simple exchange of the type wheel easily allows changing the font. Some manufacturers ( eg Brother ) one of a housing (cartridge ) had surrounded daisy wheel used, so that it remained protected even when you switch.

Typewriter manufacturers offered in the early days of the personal computer in addition to an RS -232 port for computer and printer with print wheel as computer peripherals. The daisy wheel printer achieved the better typeface than the currently widely used dot matrix printers, but were restricted to the character set of the type wheel.

History

About one hundred years ago, there were already two type carrier, the combined all types on a single body. They were the forerunners of the modern ball heads and daisy wheels.

• In type cylinder (also called type roller) the types were arranged on a cylindrical surface in several circles ( levels). The pointer Mignon Typewriter AEG had a type cylinders with twelve types into seven levels. The domed 7x12 panel of this typewriter was the unwrapped cylinder surface.
• A shorter and larger in diameter type cylinder is in the older scientific literature also called daisy wheel, although the types were usually arranged at least into two, into three levels. It allowed to drive the most common types with less mechanical effort of the keys. The type wheel of the Blickensderfer typewriter ever had 30 types into three levels, ie, had a significantly larger diameter than the cylinder type carriers of the AA.

• For both type support different typewriter models have been developed which have solved the handling and transmission of movement in different ways. For this type carriers of the modern ball head has emerged, which from the historical type cylinder by the spherical shape and the tilting movement ( rather than axial movement ) differs.

• This modern type wheel has only one plane, or on it the types are disposed in a geometrical plane. Characterized the axis of rotation is transverse, but oriented perpendicular to the sheet surface. Although such an apparent step backwards direction, the modern type wheel is considered as further technical development of a long time as no longer applicable surpassable ball head. The filigree wheel is only about half as much as the massive head ( around 5 instead of 10 grams), it comes with only one axis of motion from ( no layers ) and thus enables a simpler mechanical control, which is much cheaper than the ball head technology in manufacturing and remains virtually maintenance-free over the entire lifetime. Thus, it is mainly for economic reasons, today the only remaining stop method for typewriters.

Drive Technology

In an electro-mechanical typewriter printwheel not the car with the platen, but the print wheel is moved together with its drive motor in the line direction.

During the rotation of the type wheel, two different principles of construction are used, there are two different type wheel printing.

Endurance runners - printing

The so-called long-distance runner, the previous and now outdated technology, the daisy wheel continues to rotate at a constant speed. In the simplest version of a type of support rods is extended. His nose is happening at each revolution short a forked light barrier and generates a pulse. The fixed time intervals between pulse and write position of the types are stored electronically, so that the pin at the right moment can beat on the bar with the selected type. The stop pin beats very fast and quickly returns to its original position, so that the print wheel does not need to stop and yet sufficiently carried the imprint clearly. Instead of an elongated rod with fork type light barrier, other sensors for generating a synchronizing pulse are possible. To save energy, the " endurance runner " in writing breaks can also be switched off timed.

Alternating directional printing

When changing the direction of printing still used a stepping motor is used, the forward or backward rotates the daisy wheel located on its axis along the shortest path to the next required type. Since the daisy wheel is stationary at each impression, the stop pin can beat slower. The speed of this printing type was increased by side-by- Place frequently used types on the daisy wheel. The daisy wheel is also for generating a pulse only once for the calibration ( zeroing ) after switching on the typewriter is needed designed.

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