Sharp Kabushiki Kaisha Corporation

Noboru Kawai

Shinya Kawanishi

Zempei Tani

Kenji Hachimura

At an optoelectronic dust sensor, opening(s) is/are formed at front panel(s) of main body housing(s), and passage hole(s) is/are formed at back panel(s) of main body housing(s). Provided between such back panel passage hole(s) and front panel opening(s) is/are dust passage route(s) permitting passage of dust and/or smoke. Passage hole(s) is/are for introducing dust and/or smoke to dust passage route(s). Opening(s), being for discharging dust and/or smoke from dust passage route(s), is/are sufficiently larger than passage hole(s).

Optoelectronic dust sensor and air conditioning equipment in which such optoelectronic dust sensor is installed

An object of the invention is to provide a toner density sensor capable of detecting toner density with high accuracy without being affected by the temperature change. A light-emitting diode emits infrared light toward the toner attached to the surface of a photosensitive drum, and the infrared light reflected from the toner is received by a photodiode. An amplifier circuit for detecting color toner density and an amplifier circuit for detecting black toner density, of which both amplify outputs from the photodiode, each employ a thermister for the feedback resistance of the amplifier. An input resistance in the amplifier circuit and the thermister adjust the gain of the amplifier circuit so as to obtain optimal outputs.

Toner density sensor

A position control system for positioning a D.C. motor at a desired position operates in a speed detection mode in which the D.C. motor is driven to rotate at a predetermined high speed, and in a position detection mode wherein the position of the D.C. motor is precisely controlled. In the speed detection mode, the control circuit forms a phase-locked-loop (PLL) control circuit which compares the phases of the speed instructing pulse signal and the rectangular signal derived from the actual rotation of the D.C. motor. The motor speed is controlled in accordance with the phase difference between the speed instructing pulse signal and the rectangular signal derived from the actual rotation of the D.C. motor.

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Nabari, Japan

Noboru Kawai