To provide a drive circuit, a drive method, a display device, and a projection display device capable of increasing contrast of an image a mean gray level Gf is detected from an image signal DATA per unit time. It is thus possible to obtain a magneto-resistive effect device of improved reliability that enables a structure capable of having a narrowed read gap to be adopted to meet the recently demanded ultra-high recording density, allows a stable bias magnetic field to be applied in simple structure, and obtain a stable magneto-resistive effect change. A latency scaling parameter is calculated. The input power factor correction circuit boosts the converted DC power and the operating voltage. A process for manufacturing said sucker rod is included. The cable includes at least one conductor core and at least two coatings of plastic material and incorporates a lubricating material in andor on the outer layer of plastic material.