Apparatus for detecting amount of liquid nitrogen

• US 4,691,793 A
• Filed: 12/13/1985
• Issued: 09/08/1987
• Est. Priority Date: 12/13/1984
• Status: Expired due to Fees

• Current Assignee: Horiba Limited
• Original Assignee: Horiba Limited
• Inventors: Hosokawa, Yoshinori, Kumakura, Koichi
• Primary Examiner(s): MILLER JR, GEORGE
• Application Number:
  US06/809,111
• Time in Patent Office: 634 Days
• Field of Search: 177/210 R, 177/DIG. 6, 177/50, 177/245, 250/231 SE, 250/211 K
• US Class Current: 177/50
• CPC Class Codes: G01F 23/20 by measurement of weight, e.g. to determine the level of stored liquefied gas
• CPC Class Codes: G01G 17/04 for weighing fluids, e.g. gases, pastes
• CPC Class Codes: G01G 19/00 Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups electric measuring arrangements involving comparison with a reference value G01R17/00
• CPC Class Codes: G01G 23/36 Indicating the weight by electrical means, e.g. using photoelectric cells
• CPC Class Codes: Y10S 177/06 Photoelectric

Abstract

An apparatus for detecting an amount of liquid nitrogen, has a table for supporting a Dewar vessel in which liquid nitrogen used for cooling a semiconductor radio detector is contained. A motion conversion mechanism is engaged with the table for converting the movement of the table in the up and down direction in response to changes in the weight of the liquid nitrogen in the vessel and amplifying and movement. The motion conversion mechanism includes a disk rotated by the amplified motion of the table, and a plurality of sensors adjacent the disk for detecting the rotational position of the disk which is representative of the weight of the liquid nitrogen in the vessel.

Claims

1. An apparatus for detecting an amount of liquid nitrogen and shutting off power to a semiconductor radio detector when the amount of nitrogen is low, comprising:

a table for supporting a Dewar vessel in which liquid nitrogen used for cooling a semiconductor radio detector is contained;

a motion conversion mechanism engaged with said table for converting the movement of the table in the up and down direction in response to changes in the weight of the liquid nitrogen in the vessel and amplifying the movement, said motion conversion mechanism including a disk rotated by the amplified motion of said table;

a plurality of sensors adjacent said disk for detecting the rotational position of said disk which is representative of the weight of the liquid nitrogen in the vessel;

a signal controlled switch connected in the power supply for the semiconductor radio detector; and

control signal means connected between said sensors and said switch for supplying a control signal to turn said switch off when said sensors sense that the weight of liquid nitrogen in said vessel is below a predetermined amount.

2. An apparatus as claimed in claim 1 in which said sensors each include a light emitting part and a light receiving part positioned to receive light from said light emitting part along a path across the peripheral portion of said disk, and in which said disk has a large diameter portion and a small diameter portion around the periphery of said disk, the peripheral portion of said large diameter portion being interposable between said light emitting part and said light receiving part of the respective sensors to block transmission of light and the peripheral part of the small diameter portion being radially inwardly of the path of the light between the parts of said sensors.