THERMAL PRINTER WITH DUAL TIME-CONSTANT HEAT SINK
The present application is directed to a dual time-constant heat sink for a thermal printer. The dual time-constant heat sink includes a print head heat sink, in contact with a print head of a thermal printer, the print head heat sink having a first time constant. The dual time-constant heat sink also includes an insulator in contact with the print head heat sink; and a thermal reservoir, in contact with the insulator, the thermal reservoir having a second time constant, the second time constant longer than the first time constant.
1 . A dual time-constant heat sink for a thermal printer, comprising:
a print head heat sink, in contact with a print head of a thermal printer, the print head heat sink having a first thermal time constant;
an insulator in contact with the print head heat sink; and
a thermal reservoir, in contact with the insulator, the thermal reservoir having a second thermal time constant, the second time constant longer than the first thermal time constant.
2 . The dual time-constant heat sink of claim 1 , wherein the print head heat sink has a low heat capacity.
3 . The dual time-constant heat sink of claim 2 , wherein the print head heat sink has a thermal conductivity of at least 50 W/mK.
4 . The dual time-constant heat sink of claim 1 , wherein the thermal reservoir has a high heat capacity.
5 . The dual time-constant heat sink of claim 4 , wherein the thermal reservoir has a thermal conductivity of at least 50 W/mK.
6 . The dual time-constant heat sink of claim 1 , wherein the insulator has a low thermal conductivity.
7 . The dual time-constant heat sink of claim 6 , wherein the insulator has a thermal conductivity of less than 1 W/mK.
8 . The dual time-constant heat sink of claim 6 , wherein the thermal conductivity of the insulator is at least two orders of magnitude lower than the thermal conductivity of the print head heat sink or the thermal reservoir.
9 . The dual time-constant heat sink of claim 6 , wherein the thermal conductivity of the insulator is at least three orders of magnitude lower than the thermal conductivity of the print head heat sink or the thermal reservoir.
10 . The dual time-constant heat sink of claim 1 , wherein the insulator comprises an air gap.
11 . The dual time-constant heat sink of claim 1 , wherein the dual time-constant heat sink has no moving parts.
12 . A method for controlling temperature of a print head of a thermal printer via a dual time-constant heat sink, comprising:
preheating a print head of the thermal printer to a first predetermined temperature, the print head in contact with a print head heat sink having a first thermal time constant, the print head heat sink in contact with an insulator, and the insulator in contact with a thermal reservoir having a second thermal time constant longer than the first thermal time constant such that the print head heat sink reaches the first predetermined temperature before the thermal reservoir;
printing a first image via the print head, the print head and print head heat sink reaching a second, higher temperature, the thermal reservoir at a temperature lower than the second temperature; and
cooling, by the thermal reservoir, the print head and print head heat sink to a third temperature lower than the second temperature.
13 . The method of claim 12 , wherein the print head heat sink has a low heat capacity.
14 . The method of claim 13 , wherein the print head heat sink has a thermal conductivity of at least 50 W/mK.
15 . The method of claim 12 , wherein the thermal reservoir has a high heat capacity.
16 . The method of claim 15 , wherein the thermal reservoir has a thermal conductivity of at least 50 W/mK.
17 . The method of claim 12 , wherein the insulator has a low thermal conductivity.
18 . The method of claim 17 , wherein the insulator has a thermal conductivity of less than 1 W/mK.
19 . The method of claim 12 , wherein the insulator has a thermal conductivity of at least two orders of magnitude less than the thermal conductivity of the print head heat sink or the thermal reservoir.
20 . The method of claim 12 , wherein the insulator has a thermal conductivity of at least three orders of magnitude less than the thermal conductivity of the print head heat sink or the thermal reservoir.
21 . The method of claim 12 , wherein the insulator comprises an air gap.
22 . The method of claim 12 , wherein the dual time-constant heat sink has no moving parts.