Printing tactile images with improved image quality

1. A method of forming an electrophotographic image on a receiver medium having raised information providing a distinct tactile feel, comprising:

forming a layer of non-marking particles onto the receiver medium using an electrophotographic process responsive to tactile image data, wherein the layer of non-marking particles is in direct contact with the receiver medium;

forming one or more layers of marking particles over the layer of non-marking particles using an electrophotographic process responsive to visible image data, wherein a volume average diameter of the non-marking particles is at least 150% of a volume average diameter of the marking particles and is no more than 200% of the volume average diameter of the marking particles; and

fusing the formed layers of non-marking particles and marking particles onto the receiver medium, wherein the layer of fused non-marking particles has a maximum thickness of at least 20 μm to provide the distinct tactile feel;

wherein a surface charge density of the non-marking particles is between 30% and 60% of a surface charge density of the marking particles.

2. The method of claim 1 wherein the volume average diameter of the marking particles is between 4-9 μm.

3. The method of claim 1 wherein the layer of non-marking particles has a maximum coverage of at least 2 mg/cm 2 .

4. The method of claim 1 wherein the volume average diameter of the non-marking particles is at least 160% of the volume average diameter of the marking particles and is no more than 190% of the volume average diameter of the marking particles.

5. The method of claim 1 wherein the raised information is used to form Braille characters that can be sensed by visually-impaired persons.