Abstract: A print head apparatus is provided for use with a xerographic printing device having a rotating photoreceptor with a curved conductive surface. The apparatus includes an LED bar print head configured for locating adjacent the photoreceptor; a first distance sensor located on the print head at a first location, the first distance sensor being configured for measuring a first gap between the print head and the photoreceptor at the first location; and a second distance sensor located on the print head at a second location, the second location being different from the first location, the second distance sensor being configured for measuring a second gap between the print head and the photoreceptor at the second location. The print head is configured such that the sensors are arranged on the print head such that the sensors are configured to enable a measurement of angular position of the print head relative to the surface of the photoreceptor.

Abstract: A print head apparatus is provided for use with a xerographic printing device having a rotating photoreceptor with a curved conductive surface. The apparatus includes an LED bar print head configured for locating adjacent the photoreceptor; a first distance sensor located on the print head at a first location, the first distance sensor being configured for measuring a first gap between the print head and the photoreceptor at the first location; and a second distance sensor located on the print head at a second location, the second location being different from the first location, the second distance sensor being configured for measuring a second gap between the print head and the photoreceptor at the second location. The print head is configured such that the sensors are arranged on the print head such that the sensors are configured to enable a measurement of angular position of the print head relative to the surface of the photoreceptor.

Abstract: A print head system useful for xerographic printing includes an LED bar print head; a photoreceptor, the photoreceptor having a conductive surface; a sensor, the sensor being disposed on the LED bar, the LED bar being disposed a conjugate distance from the photoreceptor, wherein the sensor and the photoreceptor are configured to enable a measurement of the conjugate distance.