Daisy-Wheels

Daisy wheel printers came onto typewriter and computer market in 1972, introduced by Diablo, who were then very quickly taken over by Xerox.

Daisy-wheel printers are similar to the IBM Selectric in some ways, there is a similar chassis, platen and carriage.   Instead of a ball type-element the carriage holds a print wheel on a servo-motor. Both could be seen as a refinement of the Victorian Hammond   or Blickensderfer typewriters . The Selectic had a motor, but the workings were purely mechanical. A daisy-wheel print mechanism depends on electronics.

The daisy-wheel is a palm sized metal or plastic wheel with 96 spokes each carrying a petal with a printable glyph on it. The wheel clips onto the servo-motor shaft, so if a different font is wanted its just a mater of buying a different wheel and clipping it in place. There is a small advantage over the ball type element in that the daisy-wheel always had the full ASCII character set of 96 characters.

Paper and carriage move into into position pretty much as with a Selectric. The daisy-wheel rotates to select the character and a solenoid hammer hits the petal against the ribbon and the paper. The motor turning the daisy-wheel can select new characters 30 times per second, so a daisy-wheel printer can outpace the fastest human typist. It can also act as a computer printer and will be twice as fast as a Selectric.

Where the Blickensderfer needed 250 components to make a typewriter the daisy-wheel might in principle reduce that to a few dozen mechanical parts. The essential components are four things:

• a motor to move the paper using a platen
• a fairly substantial motor to move a carriage along its rail
• the servo-motor to spin the wheel to the correct character
• a solenoid to work the hammer.

Electronics to control the daisy-wheel were the other requirement. Daisy-wheel printers did not absolutely need microprocessors but as they developed they were microprocessor based with several DC servos controlling the motor position.

Being fast impact printers daisywheel machines were rather noisy. For those used to typewriters the noise itself wasn't exceptional, in fact the printers were little or no worse than a Selectric typewriter. The problem was that the print speed was several times what a typist would achieve and could be continual.

Daisy-wheel printers typically had carbon ribbons to get the best print quality. The ribbon was usually in a cartridge, priced at a level to inspire a bit of grumbling. The print quality was very good, however, particularly using single-strike ribbon which transferred a hard black character shape onto the surface to the page. With the conventional typewriter platen daisywheel printers could take any kind of standard office stationery from 60gsm bank paper to 150 gsm letterhead with an embossed logo.

Another advantage some daisy-wheel printers had was an ability to provide features like proportional spacing. In software a bit more space could be allocated to a wide letter ‘M’ than a narrow ‘I’ and the servo-motor driving the carriage positioned accordingly. Machines like the Selectric could achieve this, but only in the premium priced models.

Daisy-wheel printers were first made successfully by Diablo in 1972. Daisywheel printers seem to have been adopted quickly by DEC, who also used the companies disk drives. Diablo were taken over by Xerox within a year.

David S Lee who had led the team developing the Diablo machines left and founded Qume in 1973. Qume also produced daisywheel printers, disk drives and terminals.

Many of the electronic typewriters made by Smith-Corona, Triumph-Adler, Olivetti and so on during the 1980s and early 1990s were daisywheel based. Canon introduced a series of typewriters base on daisywheels and NEC had a Spinwriter series which used a thimble with 128 characters.

IBM switched from Selectric to Daisywheel in 1983 using Qume technology as the WheelWriter and Actionwriter 1)

Daisy-wheel printers were used for about 20 years, from their invention in 1972 through to about 1990. Problems were:

• Speed - turning to select the character and then banging it with a hammer takes some time. Designers produced statistically optimised letter distributions on the wheels but the speed never got much above 30 characters per second - great for a typewriter, poor for a printer
• Character set- a practically sized wheel had a limited print repertoire of characters - 96 on most machines, 128 on a few. There wasn't space for the box-drawing characters needed to produce a convincing form quickly.
• Colour - in principle a ribbon lift might have been possible giving red and black but these printers were never going to produce anything but text and there is a limited use for coloured text.

Daisy-wheel printers could produce graphics by positioning the full-stop against the hammer and simply using that to do the same job as a dot-matrix printer. The problem was that the printer wasn't really fast enough. The printhead would only fire at about 30 times per second, not the thousands used by a dot matrix. The carriage would need about 9 passes to do what the dot matrix would have done in one pass. Larger daisywheels with box-forming characters for forms were possible but to get graphical flexibility users began to turn to dot-matrix then inkjet and laser printers.

Laser printers now do the job that daisy-wheels once did. Some early Laser printers had a Diablo 630 emulation to make their acceptance easier.

So far as we know there are no producers of daisywheel printers remaining.