Patent GB-1366371-A (GB)
Title: Automatic sedimentation rate recorder
IPC: G01N15/05
Filed: 1971-09-09
Abstract: 1366371 Recording-apparatus A W STANDAART 9 Sept 1971 42090/71 Headings G1H and G1J [Also in Division G2] The sedimentation rate of suspended matter in a liquid (e.g. human blood) is timed and recorded for a selected period by providing a sample of the material in an elongated tube adjacent to an elongated source of radiant energy and an elongated strip of recording material, an electric timing circuit being started when the tube is placed in position to generate pulses which are counted and energize the source of radiant energy when a predetermined count is reached. The exposure apparatus Fig.9 comprises a xenon-filled discharge tube 19 with an external trigger strip or wire 19C in Fig.8 (not shown), an opaque sheet 23 bearing horizontal transparent scale markings and a recording strip 21, the sample tube 20 being inserted between the tube and the scale sheet. The recording strip 21 consists of a transparent backing coated with a water-permeable layer of hydrophobic thermoplastic material which can become less water-permeable on heating. Such a material is insensitive to normal conditions of light and heat, but by virtue of containing particles of carbon black becomes more or less water-impermeable by the heat of the discharge tube passing through those horizontal scale markings which are above the sedimentation boundary in the sample when the tube is fired. After exposure the strip 21 is washed with water to leave the image marks and numbers of the scale.  Circuitry Fig.1. A power supply unit 12H, 12L Fig.2 or 2A (not shown) provides power for the terminals of the flash tube 19 and also energizes a pulse generator 15 Fig.5 (not shown) where the rectified and clipped A.C. operates a pulse generator comprising a capacitor(15-C2) in parallel with a uni-junction transistor (15-Q1). The output of this is divided by five or six in an identical circuit (15-C3 and 15-Q2) which may alternatively be operated by an external trigger source. An alternative pulse generator Fig.5A (not shown) comprises a squarer transistor (15-Q1) followed by integrated bi-stable circuits. The pulses are fed to a counter 14 Fig.4 (not shown) comprising a chain of thirteen integrated bi-stable circuits, and to an auto set circuit Fig.6 (not shown) comprising a uni-junction oscillator (16-Q1) and thyristor (16-Q2), the latter remaining on during the count period of the circuit 14, typically one hour. At the end of this period the counter 14 supplies a pulse to the trigger circuit 18 Fig.7 (not shown) to turn on three thyristors (17-Q1, 17-Q2, 17-Q3), discharging a capacitor (18-C5) in Fig.2 (not shown) to apply a pulse through transformer (18-T2) to the trigger electrode of the flash tube 19. A photo-resistor (18-R9) senses this flash and turns on a fourth thyristor (17-Q4) in unit 17 to indicate that a flash has taken place. Further indicator lamps show that the apparatus is conditioned to commence a test period and that the period is in course of being timed. A reset circuit 13 Fig.3 (not shown) is operated by a push-button to discharge a capacitor (13-C1) to fire a Schmitt trigger (13-Q1, 13-Q2) and reset the counter 14 to zero, at the same time resetting the trigger circuit 17. A safety circuit Fig. 13 (not shown) comprises two photo-resistors straddling the "fill" mark of the sample tube so that in normal operation one of the photoresistors is conductive. Incorrect filling causes both or neither to conduct and a transistoroperated relay inhibits the passage of the reset pulse to start a new timing cycle. A plurality of units may be operated in sequence Fig.14 (not shown) so that the sedimentation of plural samples of the same blood may be recorded for different times, using external triggering.