Electric heating – Microwave heating – With diverse-type heating
Reexamination Certificate
1999-03-01
2001-11-27
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
With diverse-type heating
C219S685000, C219S686000, C219S756000, C219S763000
Reexamination Certificate
active
06323471
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for heating objects using microwave and far infrared radiation under reduced pressure for the purpose of drying, concentrating, defrosting, roasting or sterilizing the objects.
2. Description of the Prior Art
In prior art heaters which utilize microwave and far infrared radiation for drying, concentrating, defrosting, roasting or sterilizing objects, uniform heating is achieved by placing the objects in a chamber on jigs such as plates or trays and shelf-type support jig for supporting the jigs which is rotated or on a conveyor which is moved, or the objects are stirred.
However, prior art heaters having a rotatable jig for rotating objects to be heated are expensive and not suited for mass production due to the limited amount of objects that can be supported by the rotatable jig. Further, the scattering of powder and relatively light particles occurs in prior art heaters which stir objects to be dried, and because such heaters are complex and expensive, they are not preferred. Further, prior art heaters which move objects on a conveyor are quite suited for continuous production, but control of this type of heater is difficult. Namely, because objects are continuously supplied, a mixture of objects having different water contents is created, and because this makes it difficult to accurately detect the completion of heating, a high production efficiency can not be achieved. Further, because the accuracy in detecting the completion of heating is lowered, a control data base is required for each object when objects having different water contents are supplied at the time of each production, and this makes the control process extremely complicated. Furthermore, such heating apparatuses are large in scale, and this together with the lower level of accuracy requires much time and cost to obtain conforming articles. For the reasons given above, the use of heaters utilizing microwave and far infrared radiation under reduced pressure has not been widespread.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the problems described above. First, in the present invention, the objects to be dried, concentrated, defrosted, roasted or sterilized are held in plate-shaped or tray-shaped object-holding jigs stacked on a shelf-type support jig which is placed at a prescribed position in a pressure reducing chamber to heat the objects under reduced pressure, and this eliminates the problem of low productivity caused by the use of rotatable jigs and the like. Further, because the object-holding jigs are held still during processing, a large quantity of objects can be placed on the plate-shaped or tray-shaped object-holding jigs outside the pressure reducing chamber and then such plate-shaped or tray-shaped object-holding jigs can be loaded on the shelf-type support jig, and if all these are loaded using a lifter device or the like, it becomes easy to supply the pressure reducing chamber with a large quantity of objects. Furthermore, because the objects are held still instead of being agitated or the like, the present invention avoids making the heating apparatus complicated and prevents scattering inside the pressure reducing chamber. At this point, it should be mentioned that up to now it has been difficult to obtain uniform microwave heating and far infrared heating when the objects are not moved such as by rotation or agitation.
Further, prior art apparatuses and methods that continuously supply objects by moving them on top of a belt conveyor are suited for continuous production, but such arrangement makes it difficult to sufficiently control heating. Namely, for continuous production to work with such prior art arrangement, the objects must be supplied and removed in order, and because this normally causes the immediately supplied objects having a high water content to mix with the objects that are near the completion of heating and have a low water content, the balance between the quantity of water vapor created and the quantity of exhaust removed by the vacuum pump does not obey a fixed law, and this leads to an irregular change in the reduced pressure level, which in turn makes it impossible to confirm the change in the reduced pressure level and the amount of change in the reduced pressure level in order to carry out high precision heating control. However, by the means described in the appended Claims, heat control in the present invention is carried out for individual batches of large quantities of objects to be dried, concentrated, defrosted, roasted or sterilized, and because all the objects in a single batch have roughly the same water content and are arranged at a prescribed position within the pressure reducing chamber, the change in the reduced pressure level and the amount of change in the reduced pressure level can be confirmed to obey a fixed law, and this makes it possible to carry out high precision heating control.
Now, in the embodiments of the present invention described in, the objects to be dried, concentrated, defrosted, roasted or sterilized are loaded on non-rotating plate-shaped or tray-shaped object-holding jigs stacked on a non-rotating shelf-type support jig placed at a prescribed position within the pressure reducing chamber, and because the objects are not agitated, there is no need for a rotation axle, whereby it becomes possible to reduce space loss, achieve a sufficient microwave depth penetration and significantly increase the surface area and holding capacity of the objects. Furthermore, the use of a lifting device makes it possible to easily and quickly load the object-holding jigs into the pressure reducing chamber, and because this speeds up the overall processing time, the use of a lifting device with the present invention is suited for mass production. Moreover, because the objects are not agitated, the present invention prevents the scattering of objects inside the pressure reducing chamber, and because this soiling of the inside of the pressure reducing chamber, the present invention makes it possible to improve maintenance and controllability. Further, the present invention is suited to achieve a high precision, uniform heating even when the objects are heated while held in place at a prescribed position instead of being moved on a conveyor or the like. Namely, in order to carry out a high precision control of heating, it is necessary to obtain the change in the reduced pressure level based on the balance of the water vapor content and the amount of exhaust of the vacuum pump, or the change in the water content of such exhaust, but in continuous supply methods such as the conveyor method in which objects having a high water content are continuously supplied, the objects that have just been supplied but not yet heated mix with objects that are near the completion of heating, and for this reason such systems do not display changes in the reduced pressure level according to a prescribed law, and this makes it difficult to obtain either the change in the reduced pressure level or the change in the water content of the exhaust to be used for control purposes. However, in the present invention, because only objects having roughly the same water content are present in the pressure reducing chamber, the balance between the amount of water vapor created and the amount of exhaust of the vacuum pump can be measured in accordance with a prescribed law, and this makes it possible to confirm that the change in the reduced pressure level and the amount of change in the reduced pressure level obey a prescribed law. Further, in the case where the amount of water vapor is measured, an extremely precise measurement of the increase thereof can be taken, and this makes it possible for the present invention to carry out high precision dryness level detection.
In one embodiment, the heating apparatus is provided with a shelf-type support jig having reflector plates arranged at the top and bottom surfaces thereof, and in this way the objec
Hedman & Costigan ,P.C.
Leung Philip H.
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