Microfilm printer

{
  "publication_number": "US3768714A",
  "country": "US",
  "kind": "A",
  "title": "Microfilm printer",
  "abstract": "A microfilm printer is disclosed for printing computer output data on microfilm. The film is advanced along a transport incrementally one line for each line of computer output data, and a line of data is imaged on one side of the film while the film is stopped between incremental advances. Periodically, generally much less often than the imaging of data lines, the image of a form is projected onto the film from the other side so that the film where finally developed displays the data entered in the form. The film transport disclosed employs a new incremental drive capstan for advancing the film on a line by line basis past an exposure station, with a pair of drive capstans employed to transport film to and from the incremental drive capstan from and to, respectively, supply and take-up reels. The incremental drive capstan is started and stopped by electromagnetic brakes in which the starting and stopping times of the capstan are controlled by removal of electrical current from one of the brakes. A separate lens system is employed for projecting each of the data and form images onto the film to facilitate matching the data to the form. The film transport is controlled to permit the film to advance a multiple number of data lines between times when the film is stopped at a data line to speed up the printer''s response where no data is provided for some lines of the form.",
  "claims": [
    "1. In a web transport for moving a web along itsslength rapidly and stopping said web accurately after predetermined short distances of web travel, the transport having: a. an elongated drive shaft with a generally cylindrical web Engaging surface thereon, b. a frame rotatably supporting said shaft, c. drive means on said frame for rotating said shaft, d. a clutch interconnecting said drive means and said shaft, and e. an electrically controlled brake interconnecting said shaft and said frame, in which: a. said clutch comprises driving and driven members mounted adjacent to each other, a fluid mixture of ferromagnetic particles between said driving and driven members for connecting said members together, and an electromagnetic coil adjacent to said driving and driven members for generating a magnetic field to solidify said fluid mixture with said driving member connected to said drive means and with said driven member connected to said shaft, b. said brake comprises driving and driven members mounted adjacent to each other, a fluid mixture of ferromagnetic particles between said driving and driven members for connecting said members together, and an electromagnetic coil adjacent to said driving and driven members for generating a magnetic field to solidify said fluid mixture with said driving member connected to said shaft and with said driven member connected to said frame, and c. control means are connected to said clutch and brake for starting and stopping said shaft by reducing the current to the coil of said brake to start said shaft and reducing the current to the coil of said clutch to stop said shaft said control means comprising means: to maintain said shaft stopped with an electrical current to the coil of said clutch maintained at a first level and an electrical current to the coil of said brake maintained at a second level wherein the current at the first level generates a driving force on the shaft lower than a braking force on the shaft generated by the current at the second level; to start said shaft rotating with the current to the coil of said brake reduced to at least the first level and the current to the coil of said clutch raised and maintained above the level of the current in the coil of said brake; and, to stop said shaft with the current to the coil of said clutch reduced to at least the level of the current in the coil of said brake and the current to the coil of said brake raised.",
    "2. The web transport of claim 1 wherein said control means comprises means to start said shaft rotating with the current to the coil of said clutch raised to at least the second level and to stop said shaft with the current to the coil of said brake raised to the second level.",
    "3. A method of rapidly starting and stopping a rotatable drive shaft having a magnetic particle device connected to operate as a clutch to provide driving torque to said shaft when a current is applied to the coil of said device and a further magnetic particle device connected to provide a braking torque to said shaft when a current is applied to the coil of said further device comprising: establishing a current in coil of said driving device when said drive shaft is in a steady-state stopped condition, establishing a current in the coil of said braking device when said drive shaft is in a steady state stopped condition, said braking device current exceeding said driving device current, removing said braking device current to start rotation of said drive shaft, re-establishing a current in said braking device after rotation of said drive shaft is established, said re-established braking device current less than the current in said driving device, removing said driving device current and re-establishing said first mentioned braking device current to stop rotation of said drive shaft, and re-establishing said first mentioned driving device current when said drive shaft stops rotating."
  ],
  "cpc": [
    "G09G 3/008",
    "G03B 2217/243",
    "G03B 27/465",
    "G03B 27/587",
    "G06K 15/12",
    "G06K 15/1295"
  ],
  "assignees": [
    "MEMOREX CORP"
  ],
  "filing_date": "1971-06-03",
  "publication_date": "1973-10-30",
  "grant_date": "1973-10-30",
  "priority_date": "1969-10-06",
  "application_number": "US-3768714D-A",
  "family_id": "26846982",
  "citations": [
    "US2702016A",
    "US2813605A",
    "US3208567A",
    "US3275208A",
    "US3332084A",
    "US3394853A"
  ]
}