Thermocopier

an office machine used for quick copying and reproduction of documents by thermography. The technological process for obtaining thermographic copies involves the exposure of a heat-sensitive material to infrared radiation, either separately or together with a copy base consisting of ordinary paper, and the developing of an image or the transfer of the image to the copy base.

Figure 1. External appearance (a) and diagram (b) of a TEKA-II thermocopier (USSR): (1) sheet-feeding device, (2) drive roller, (3) glass drum, (4) reflector, (5) lamp, (6) holder roller, (7) guides for removal of copy set, (8) fan, (9) housing, (10) lever for drive roller, (11) lamp switch, (12) guides for insertion of copy set

The main elements of a thermocopier (Figure 1) are the sheet-feeding device, a glass drum containing a source of infrared radiation (for example, an incandescent lamp), an electric drive, and a fan. The original and the heat-sensitive material pass between the glass cylinder and a holder roller and are irradiated by an infrared beam. The drive permits infinite variation of the exposure time. Copies may be made on a thermocopier from transparent and nontransparent, one-sided and two-sided originals with a line image (text, blueprints, and line drawings). Transparent and semitransparent one-sided originals are copied primarily by transillumination, whereas nontransparent one-sided and two-sided originals are copied only by the reflex method (Figure 2).

Figure 2. Copy sets (carriers): (a) for making copies using thermal copy paper (transfer method), (b) for making copies on thermoreactive paper (contact method)

Thermocopiers can produce three to ten copies a minute; the largest format that can be copied ranges from 200 × 300 mm to 300 × 450 mm, depending on the type of machine.

Thermocopiers can also be used for the application of protective plastic coatings to originals (lamination) and for the production of copies on transparent film for projectors.