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Pneumatic File Protect with Thermistor

IP.com Disclosure Number: IPCOM000091477D
Original Publication Date: 1968-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Helle, RB: AUTHOR [+2]

Abstract

The physical status of a groove is detected by a probe-positioned piston. Such blocks or permits air passage to actuate an electrical switch such as a thermistor for providing an electrical indication of the condition of the groove. The device is particularly useful for sensing whether or not the file protect ring is present in a reel of tape.

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Pneumatic File Protect with Thermistor

The physical status of a groove is detected by a probe-positioned piston. Such blocks or permits air passage to actuate an electrical switch such as a thermistor for providing an electrical indication of the condition of the groove. The device is particularly useful for sensing whether or not the file protect ring is present in a reel of tape.

As shown at A, when groove 10 in reel 11 is open, the probe of piston 12 is able to project into 11 and, therefore, piston 12 blocks port 15 which is under continuous air pressure. Thermistor 16 operates in a self-heating mode and, since it is not cooled by any air flow when port 15 is blocked, it produces a relatively low resistance. This low resistance can be detected at terminals 17 and converted into a signal indicating a file protected condition.

However, when ring 18 is inserted into 11, the probe of piston 12 forces 12 back so as to uncover pressure port 15 as shown at B. The presence of pressure at port 15 then forces 12 back against spring 19 until it is completely compressed as shown at C. This uncovers the thermistor port 20, allowing air to flow over thermistor
16. The latter is cooled, thus increasing its resistance substantially, which indicates that the file is not protected. The advantage of this system is that there are no moving electrical contacts. However, a pressure contact can be coupled to the output of port 20, if desired.

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