Detecting contact between print apparatus components and photoconductive surfaces
In an example, a method includes charging a photoconductive surface in a print apparatus and monitoring an electrical parameter associated with a proximity of a print apparatus component to the photoconductive surface. A relative spacing between the print apparatus component and the photoconductive surface may be changed and a contact between the print apparatus component and the photoconductive surface may be detected when the electrical parameter meets predetermined criteria.
1. A method comprising:
charging a photoconductive surface in a print apparatus;
monitoring an electrical parameter associated with a proximity of a print apparatus component to the photoconductive surface;
progressively reducing a relative spacing between the print apparatus component and the photoconductive surface in increments until the electrical parameter meets a predetermined criteria; then
increasing the relative spacing; and
reducing the relative spacing progressively in smaller increments until the electrical parameter meets the predetermined criteria.
2. A method according to claim 1 in which the method is carried out iteratively until the relative spacing is reduced by a minimum available increment.
3. A method according to claim 1 wherein monitoring the electrical parameter comprises monitoring a current value or a voltage value.
4. A print apparatus comprising a print apparatus controller, a photoconductive surface and a print apparatus component, wherein:
the print apparatus controller is to selectively cause the print apparatus component to contact the photoconductive surface and the print apparatus controller comprises a calibration module;
wherein the calibration module is to monitor an electrical condition of the print apparatus indicative of a relative spacing between the print apparatus component and the photoconductive surface when the photoconductive surface is charged and to reduce a relative spacing between the print apparatus component and the photoconductive surface in increments until a predetermined electrical condition is detected; then
increase the relative spacing; and
reduce the relative spacing progressively in smaller increments until the electrical parameter meets the predetermined criteria.
5. A print apparatus according to claim 4 in which the print apparatus component comprises a power supply, a parameter measuring unit and a roller which, in use of the print apparatus, contacts the photoconductive surface.
6. A tangible machine readable medium comprising instructions which, when executed by a processor, cause the processor to:
control a print apparatus to:
progressively reduce a spacing between a print apparatus component and a photoconductive surface of the print apparatus in increments until an electrical condition of the print apparatus component is indicative of contact between the print apparatus component and the photoconductive surface; then
increase the relative spacing; and
reduce the relative spacing progressively in smaller increments until the electrical parameter meets the predetermined criteria; and
determine a set point for the print apparatus based on a state of the print apparatus when contact is detected.
7. A tangible machine readable medium according to claim 6 comprising instructions to determine a set point which is indicative of a condition of a pair of laterally spaced drive motors.
8. A tangible machine readable medium according to claim 7 comprising instructions to determine a set point which is indicative of a condition of each of the laterally spaced drive motors.