HEATING DEVICE AND METHOD OF MANUFACTURING MAGNETIC RECORDING MEDIUM
To provide a heating device capable of heating a surface of a workpiece having a disk shape with a hole in the center at high productivity and uniformity, a heating device for heating a workpiece by irradiating workpiece with light has a feature that I 1 /I 2 is 1.00 or less, and I 3 /I 2 is 0.90 or more 1.50 or less, where I 1 represents average amount of light irradiation on first region in which the hole of the workpiece is formed, I 2 represents average amount of light irradiation on second region surrounding first region from outer side, I 3 represents average amount of light irradiation on third region extending from outer periphery of second region to outer periphery of workpiece, provided that the radius of outer periphery of second region is 0.30R H +0.70R W , where R H represents the radius of the hole, and R W represents the radius of outer periphery of the workpiece and third region.
1 . A heating device for heating a workpiece having a disk shape with a hole in a center and having a pair of main surfaces opposite to each other by irradiating the workpiece with light, the heating device comprising:
an irradiating part facing at least one main surface of a pair of main surfaces of a workpiece and configured to irradiate the workpiece with the light,
wherein the irradiating part includes a plurality of light emitting elements on a surface thereof facing the at least one main surface of the workpiece,
in a case where a plane including the main surface of the workpiece is defined as an irradiation-target surface, the irradiation-target surface includes a first region in which the hole of the workpiece is formed, a second region surrounding the first region from an outer side, and a third region extending from an outer periphery of the second region to an outer periphery of the workpiece, and
in a case where a radius of the hole is defined as R H , a radius of the outer periphery of the workpiece is defined as R W , a radius of the outer periphery of the second region is defined as 0.30R H +0.70R W , and a radius of an outer periphery of the third region is defined as R W , and an average amount of irradiation of the light on the first region is defined as I 1 , an average amount of irradiation of the light on the second region is defined as I 2 , and an average amount of irradiation of the light on the third region is defined as I 3 , I 1 /I 2 is 1.00 or less, and I 3 /I 2 is 0.90 or more and 1.50 or less.
2 . The heating device according to claim 1 ,
wherein a minimum value of an irradiation intensity of the light on each of the second region and the third region is 0.80 times or more and 1.50 times or less the average amount of irradiation of the light on the region.
3 . The heating device according to claim 1 ,
wherein the second region includes a 21st region adjacent to the first region and a 22nd region positioned on an outer side of the 21st region, and
in a case where a radius of an outer periphery of the first region is defined as R W1 and the radius of the outer periphery of the second region is defined as R W2 , a radius of the 21st region is defined as 0.50R W1 +0.50R W2 , and an average amount of irradiation of the light on the 21st region is defined as I 21 and an average amount of irradiation of the light on the 22nd region is defined as I 22 , I 21 /I 22 is 0.70 or more and 1.50 or less.
4 . The heating device according to claim 1 ,
wherein a distance between the irradiating part and the workpiece is 0.050 time or more and 2.0 times or less the radius of the outer periphery of the workpiece.
5 . A method of manufacturing a magnetic recording medium comprising forming a magnetic layer on a workpiece having a disk shape with a hole in a center and having a pair of main surfaces opposite to each other, the method comprising after the forming:
heating the workpiece by irradiating the workpiece with light,
wherein the heating is performed by irradiating at least one main surface of the pair of main surfaces of the workpiece with light by an irradiating part including a plurality of light emitting elements on a surface of the irradiating part facing the at least one main surface of the workpiece,
in a case where a plane including the main surface of the workpiece is defined as an irradiation-target surface, the irradiation-target surface includes a first region in which the hole of the workpiece is formed, a second region surrounding the first region from an outer side, and a third region extending from an outer periphery of the second region to an outer periphery of the workpiece, and
in a case where a radius of the hole is defined as Ru, a radius of the outer periphery of the workpiece is defined as R W , a radius of the outer periphery of the second region is defined as 0.30R H +0.70R W , and a radius of an outer periphery of the third region is defined as R W , and an average amount of irradiation of the light on the first region is defined as I 1 , an average amount of irradiation of the light on the second region is defined as I 2 , and an average amount of irradiation of the light on the third region is defined as I 3 , I 1 /I 2 is 1.00 or less, and I 3 /I 2 is 0.90 or more and 1.50 or less.