| 摘要 |
1,109,269. Photo-electric measurement of boiling point. MEPAG A.G. Dec. 13, 1966 [July 29, 1966], No.55833/66. Heading G1A. The boiling point of a liquid is measured by photo-electric investigation of the vapour bubbles formed when the liquid is heated. Liquid in a test tube 1 is heated by means of an oven 3, the temperature of which is monitored by a sensor 4. Light from a lamp 6 is transmitted through a heat proof glass light guide into the liquid, and reflected on to a cadmium sulphide photo-resistor 8 by any vapour bubbles, produced when the liquid nears the boiling point, passing the hole 7. The output of the detector 8 comprises pulses, of duration dependent on the time taken for a bubble to pass in front of the detector observation hole 7, which is of rectangular or square section. The amplitude of a pulse is dependent on the surface area of the bubble being detected. The voltage pulse occurring across resistor 9 is amplified by a transistor amplifier including input and output transistors 11, 12. The amplifier output is applied to capacitor 13 which charges to a voltage proportional to the length and amplitude of the pulse. The occurrence of further pulses (due to more bubbles passing the observation hole 7) maintains the capacitor in a charged state, and the voltage attained, or the discharge current through resistor 14 thus indicates the amount of vapour (in the form of bubbles opposite the observation hole) being produced at any one time. The resistor 14 may be replaced by a relay energizing coil and thus actuate the relay at a predetermined voltage which represents boiling of the liquid. The relay can control recording or indication devices or switch off the oven. |
