Patent GB-1389181-A (GB)
Title: Chart recorder
IPC: G01D15/20
Filed: 1973-01-03
Abstract: 1389181 Chart recorders HONEYWELL Inc 3 Jan 1973 [5 Jan 1972] 323/73 Heading G1J A chart recorder comprises a print carriage 54 having two parts 58, 52, one part 58 being constrained to move on a fixed shaft 298 lengthwise of a drum or platen (278) over which a strip of recording material 185 is fed between supply and take-up rollers, and the other part 52 being pivotally mounted on the part 58 for rocking movement about a shaft 56 relative to the platen, two print wheels 120, 122 mounted on the part 52, print wheel 122 being mounted for displacement in a plane parallel to that of the print wheel 120 the axis of which is fixed relative to the part 52, a print wheel advance mechanism responsive to the rocking motion of the part 52 so as to effect rotation of both print wheels in unison, and print selection means operable selectively to position the print wheel 122 such that it either prints or does not print on the recording material 185 when the print wheel 120 prints. Preferably the print wheel 122 prints numerals and the print wheel 120 dots such that when the recorder is adapted to record a plurality of traces on the chart 185, e.g. as in Fig. 14, each trace, comprising a series of dots, is identified at regular intervals by a corresponding numeral. The carriage 54 is connected by a cable (292) for movement lengthwise of the shaft 298 in response to the output of a potentiometer (not shown) which for example may be connected by a switch 22 to each of a number of thermocouples in turn. The switch 22 is driven from a motor 14 via a geneva movement 20. Drive motor 14 also drives an output shaft 24, gear 28, shaft 30 and gears 32, 34. Gears 32, 34 respectively drive gears 36, 40 in unison. An eccentrically-mounted orbiting rod 44 driven by gears 36, 40 engages runners 46, 48 of the part 52 to effect its rocking motion. A switch (288) having an actuating arm (290) contactable by the rod 44 cuts off power to the drive of the carriage 54 when the print wheels 120, 122 are in contact with the chart 185. The dot print wheel 120 is mounted on a hub 140 for rotation with a shaft 144, and the numeral print wheel 122 is mounted on a hub 148 for rotation with a pivot arm 136 on a shaft 134. A manually-positionable cam disc 210 holds the pivot arm 136 depressed against the bias of spring 220 so that a numeral is printed every time a dot is printed or allows the arm 136 to retract the print wheel 122 out of coaxial alignment with the print wheel 120. In the latter position a roller 222 mounted on pivot arm 136 can be acted upon by a rotary cam 127 to restore the alignment of the two print wheels 120, 122 at regular intervals so that a dot and a numeral can be printed together. A ratchet wheel 90 engaged by spring-biased pawls 88, 108 is advanced each time the part 52 is rocked by the rod 44. A gear train comprising a sun gear 124, a planetary gear wheel 126 fixed for rotation with the cam 127, an idler gear wheel 132, and gear wheels 138, 146 coupled to print wheels 120, 122, transmits the drive of the ratchet wheel 90 to the print wheels 120, 122. For each rocking stroke of the part 52 the gear train advances both print wheels 120, 122 to bring the next peripheral dot and number to face the platen (278). At the same time rotary cam 127 is advanced, and its lobe(s) defined by one or more set screws 128 periodically engages roller 222 to move pivot arm 136 so bringing print wheel 122 into a printing position. The shaft 56 also supports a hub (158) keyed for rotation with the ratchet wheel 90 by engagement of a pin (172) in an aperture (174). The hub (158) supports a multi-coloured ink pad wheel 162 composed of a number of ink pads separated by radial fins 190. The ink pads are engaged by the dots 188 and numbers 192 on the peripheral surfaces of the print wheels 120, 122 such that the wheels are inked, and the traces printed and their identifying numerals are each printed with ink from a respective ink pad.