| 摘要 |
1,170,426. Constant temperature containers. TEXAS INSTRUMENTS Inc. 10 Nov., 1966 [3 Jan., 1966], No. 50394/66. Heading H1E. A constant-temperature oven for, e.g. a crystal or an electronic component comprises two heating elements made of materials having a steep, positive temperature coefficient (PTC) of resistivity, one element being received within the other. The outer and inner elements respectively consist, as shown, of annuli 58, 54 and discs 59, 60; 55, 66, the inner set defining a cavity 20 for the reception of components 9. The cavity is lined with an insulant 26 and a layer 22, e.g. of aluminium to prevent axial temperature gradients. The discs and annuli are separated by conductive layers 41-52 which are alternately connected to conductors 64 and 68 and thence to base pins 1 and 3. The PTC material used may be lauthanum-doped barium titanate (Ba. 997 La. 003 TiO 3 )which in the neighbourhood of the Curie point has a very steep characteristic. The inner and outer elements may be separated by an insulating layer 62 and the inner element may have a higher Curie point than the outer element. More than two elements may be used with increasing Curie points towards the cavity. The elements are surrounded by a mass of insulation 30 contained within a cap 86. |
