Abstract: A charger for initial charging is built on the surface of a photosensitive drum. A discharge lamp removes the charge from the photosensitive drum. A current detection unit detects the current flowing from the photosensitive drum upon the removal of the charge from the surface of the photosensitive drum by the discharge lamp. A control unit compares a current which is detected by a current detection unit with a reference value which is initially stored in a memory and generates a digital value corresponding to a difference error between them. An A/D converter converts the digital value which is generated from the control unit into an analog current for supply to the first-mentioned charge. The aforementioned process is repeated by an instruction of the control unit until the difference value between the current detected by the current detection unit and the reference value comes within an allowable range.

Abstract: An image forming apparatus includes an automatic toner supplier for detecting a toner density using a toner sensor and automatically supplying a toner when the toner density is decreased. The toner sensor is automatically initialized when initial use of the image forming apparatus is started so as to generate an analog voltage signal having a predetermined level corresponding to a reference toner density. That is, an output voltage from the toner sensor is converted into a digital signal by an analog/digital (A/D) converter. A comparator compares this digital signal with a reference voltage corresponding to the reference toner density. An arithmetic-logic unit adds/subtracts a digital adjustment value in accordance with a comparison result from the comparator. This adjustment value is converted by a digital/analog (D/A) converter into an analog control voltage signal and is applied to the toner sensor.

Abstract: An equal voltage is applied to a corona shielding case and a screen grid, when a normal mode is set, while a switch is changed over to connect the shielding case to ground when a photo mode is set. Therefore, part of a discharge voltage from a corona discharger is grounded in the photo mode. It is therefore possible to make the surface potential of a photosensitive body in the photo mode in which the shielding case is grounded lower than that in the normal mode in which the shielding case of the corona discharger is placed at a potential corresponding to an output direct-current voltage of a high-tension transformer. As a result, half-tones of photographs can be reproduced effectively.

Abstract: A process for preparing a catalyst for cleaning exhaust gases comprising a refractory carrier composed mainly of alumina and having deposited thereon, iron oxide, cerium oxide and at least one noble metal element, which comprises impregnating said carrier with(a) an aqueous solution A prepared by adding aqueous ammonia to an aqueous solution containing a water-soluble iron salt as a material for iron and a cerium salt of an organic acid as a material for cerium to adjust the pH of the aqueous solution to 6.0-9.0, and optionally adding an ammonium salt of an organic acid, and(b) an aqueous solution B containing a compound of the noble metal element.

Abstract: A process for producing an auto exhaust gas catalyst capable of simultaneously removing hydrocarbons, carbon monoxide and nitrogen oxides, which comprises depositing on a refractory inorganic support, 0.5 to 30 g of cerium, 0 to 20 g of iron, 0 to 10 g of lanthanum, 0.005 to 0.3 g of rhodium, 0.05 to 3.0 g of platinum, 0 to 1.2 g of palladium and 0 to 0.5 g of phosphorus as elements per liter of the finished catalyst in any desired sequence.

Abstract: The present invention relates to a catalyst for purifying exhaust and waste gases which is capable of simultaneously removing nitrogen oxide, carbon monoxide and hydrocarbons from the exhaust gases, comprising supporting phosphorus, barium, rhodium and at least one member selected from the group consisting of palladium and platinum, and optionally nickel on a carrier, and a method for preparation thereof.

Abstract: A catalyst for removing nitrogen oxides, carbon monoxide, and hydrocarbons in exhaust gases, said catalyst being prepared by supporting copper and nickel on a carrier and then further supporting at least two components selected from the group consisting of iridium, rhodium and ruthenium, the atomic weight ratio of copper to nickel being 0.2 to 5, the atomic weight ratio of the sum of copper and nickel to the sum of at least two components selected from the group consisting of iridium, rhodium and ruthenium being 10 to 100,000, and the total weight of copper and nickel being 10 to 200 g per liter of the catalyst.