Abstract: The present invention provide a carrier for development of electrostatic latent images, comprising magnetic powder dispersed in binder resin, the carrier having a mean particle size in a range of 30 to 80 .mu.m and satisfying the following relational expression:(x).sup.2 /.phi..sup.2 .gtoreq.9.0wherein x represents mean particle size of the carrier and .phi..sup.2 represents variance of particle size distribution.The carrier of the present invention is superior in chargeability and fluidity and free from occurrence of carrier adhesion even when used in combination with small particle size toner and which can form excellent copy images.

Abstract: A printer having a print head with a mounting portion, and a carriage with a supporting structure engaging the mounting portion of the print head to hold it in place on the carriage. The supporting structure includes a lateral positioning portion for positioning the print head laterally in a direction of movement of the carriage, a downward positioning portion for positioning the print head downwardly of the carriage, and a rear wall for receiving a force of reaction of the print head upon printing action on a platen. The printer comprises a biasing device for biasing the mounting portion of the print head downwardly and rearwardly against the downward positioning portion and rear wall of the supporting structure of the carriage, respectively. The carriage may include a serrated portion fixedly engaging a toothed belt for driving the carriage along the platen.