| 摘要 |
<p>1,221,350. Photo-electric toner concentration control. ADDRESSOGRAPH-MULTIGRAPH CORP. May 1, 1968 [June 14, 1967], No.20670/68. Heading G1A. [Also in Divisions G2 and G3] Apparatus which monitors and controls the concentration of toner in a developer mix in an electro-photographic apparatus comprises a probe 34 having a surface 36 which carries a uniformly distributed toner attracting charge and which contacts the mix, e.g. by rotation of the probe by shaft 40, and a photo-electric detector 44 for measuring the amount of toner retained on the surface, toner 30 being added to the mix when the amount of toner detected is less than an optimum concentration so as to obtain an optimum concentration. The photo-electric detector includes a light source and a light responsive photo-diode mounted within a housing 46 of material triboelectrically similar to the toner to avoid deposition of toner particles within the housing. A thermistor is also mounted within the housing so that a temperature independent signal corresponding to the amount of toner deposited on the surface may be obtained. The monitoring apparatus is disposed within a trough 24 through which the mix is circulated by augers 18, 20 to a magnetic brush assembly 26 formed on the surface of a cylinder (14) Fig.2 (not shown) within which a magnet (16) is mounted. The signal from the photo-diode is fed to a transistor amplifying and relay circuit, Fig. 4 (not shown) to control the vibration of toner hopper 32.</p> |
