FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1943
1943 - 2837.PDF
DECEMBER 2ND, 1943 FLIGHT 6,7 MICROCRAM SERVICE PROCESSING TANKS DRIER GUILLOTINE '48SST The Williamson universal Multiprinter.The printing head is interchangeable with that of the Microprinter used by the G.P.O.The Multiprinter head has the mechanism for making contact prints from film nega-tives and also for pre-viewing the negative to determine exposure. Paper up to 9m.wide can be used. Output is up to 1.000 . 7in. x 7in. prints per hour. gained and providing for the production of a larger andfaster Microprinter, specially designed for the purpose in view. Williamsons' design to this specification wasapproved early in 1941 and work was commenced imme- diately on a sample model. Coincident with this action, the Air Ministry decidedthat the Service requirements called for a machine with a larger capacity than the sin.xsin. capacity of the earliermachine. Since the processing and drying requirements of the two Services were' identical, Williamsons proposed thata universal machine should be produced with interchange- able printing heads suitable to the individual requirementsof each Service. It was agreed thai this should be done, and the two complete machines are now in full production,the one used by the R.A.F. being known as the Multi- djmnter, and that used by the G.P.O. as the Microprinter. These machines are the result not only of Williamsons'many years' experience combined with that of the G.P.O. and the R.A.F., but also incorporate Mr. Ellis Graber's30 years' experience with this type of apparatus. In the consideration of the design of a machine suitablefor the two Services, many points had to be considered, not the least being the fact that many of the Multiprintersare installed in. vehicles, to form mobile photographic units for the R.A.F., compelling every detail to be studied towithstand vibration in transit. 1,000 Prints per Hour Paper up to g£in. wide can be used, and the outputranges from 450 to 800 feet per hour, according to require- ments. A steady output of 1,000 7m. xyin. prints can bemaintained per hour. In the Multiprinter the printing head incorporates thenecessary mechanism to perform repeatedly the functions required to make contact prints from film negatives, to-gether with means for previewing the negative in order to assess the exposure required. Incidentally, the mechanismis totally enclosed in an "oil bath " gear box which would do justice to a small car, and is certainly more complicated.The paper is also perforated at each exposure for the pur- pose of operating a cutter after the drying operation,whereby cut prints are delivered from the machine. In the Microprinter head the fact that the paper is travel-ling continuously means thai the driving mechanism is extremely simple, and the main points of interest are con-cerned with the projector head. The first series of Microprinters followed the lines ofdevelopment initiated by Messrs. Gill and Paul, wherein the film projector was mounted above the paper, projectingvertically downwards. The magnification required of 8—1 naturally resulted in the projector head being mountedsome distance above the paper feed rollers, and solution of the inherent problem of producing an accurate andlasting transmission system, free from any minute irregu- larity between paper and film, is an essential requirementif definition is not to suffer. Ensuring Good Definition Experimental work on this question persisted, and manymethods were tried before the present patented method was designed. In this the paper feed roller and the filmsprocket are mounted on one shaft, the diameter of the former being eight times the latter, and the projected imageof the film is diverted by two surface-silvered mirrors so as to return on to the paper roller. The projector followsorthodox lines, with a 250-watt projector lamp condenser system and projection lens. The film passes over a curvedtrack at the gate, a condition which is permissible without affecting flatness of field owing to the small amount of film(less than one-tenth) which is projected. A Dallmeyer 2in. "focus f/3.5 enlarging lens is used for projection. In thePost Office experiments a Goertz-Elmar had been used, and some doubts were expressed as to whether the opticalperfection of this lens could be repeated, but Dallmeyers' confidence in their products has been substantiated by theresults obtained.* It is hoped that this important application of the photo-graphic process to the requirements of war will have peace- time uses. Much credit foi the development of the systemand the equipment must go to Mr. Paul and Mr. Gill, of the G.P.O. Research Station, who have worked on thetransmission of mail by photographic means, without pub- licity, and who have given great help in the productionof the Williamson Microprinters now coming into active service. • Due credit must be given to Chance Brothers who supplied the high-classoptical glass required by Dallineyer.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
