Recording medium including a first and second print layer with a controlled inclination angle and method of making the same
First and second print layers extend on the surface of a medium body in a recording medium. The first print layer has a first thickness. The second print layer has a second thickness larger than the first thickness. A print protection layer covers over the first and second print layers on the surface of the medium body. An inclined surface is defined on the surface of the print protection layer. The inventors have found that a print layer has various thickness based on the kind of colors. The difference in the thickness causes a step on the surface of the print layer at the boundary between the different colors. The inclined surface is established on the surface of the print protection layer based on the step. A smooth relative movement can thus be realized between a head and the surface of the print protection layer.
1. A recording medium comprising:
a medium body holding data;
a first print layer extending on a surface of the medium body, said first print layer having a first thickness;
a second print layer extending on the surface of the medium body, said second print layer having a second thickness larger than the first thickness; and
a print protection layer covering over the first and second print layers on the surface of the medium body, said print protection layer having an inclined surface formed at a boundary between the first and second print layers and inclined relative to the surface of the medium body,
wherein an inclination angle is set smaller than 0.49e −0.2x [degrees] between the inclined surface and the surface of the medium body where X[m/s] denotes a relative velocity between a recording track on the medium body and a head, wherein X is approximately equal to 1.2-4.8 [m/s].
2. The recording medium according to claim 1 , wherein said inclined surface descends outward from a contour of the second print layer.
3. The recording medium according to claim 2 , wherein said inclined surface descends outward from a contour of the first print layer.
4. The recording medium according to claim 1 , wherein said first and second print layers are located adjacent each other.
5. The recording medium according to claim 1 , wherein said medium body comprises a magnetic recording layer extending on a surface of a substrate.
6. The recording medium according to claim 5 , wherein said substrate is made of a transparent material.
7. The recording medium according to claim 1 , wherein at least said second print layer is printed in mixture of primary colors.
8. A method of making a recording medium, according to claim 1 comprising:
preparing a medium body holding a print layer on a surface of a substrate, said print layer printed in colors;
dropping a drop of fluid of a resin material during rotation of the medium body at a first velocity;
driving the medium body for rotation at a second velocity higher than the first velocity so as to spread the fluid over a surface of the print layer based on a centrifugal force; and
driving the medium body for rotation at a third velocity higher than the second velocity.
9. The method according to claim 8 , wherein duration of the rotation at the third velocity is set shorter than duration of the rotation at the second velocity.