Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism
Patent
1997-04-28
1999-12-21
Sniezek, Andrew L.
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
360 7304, 360 75, 340584, G11B 1518
Patent
active
060057351
DESCRIPTION:
BRIEF SUMMARY
It is known that electrical appliances cause power losses during their operation, as a result of which a corresponding generation of heat arises. This generation of heat occurs in particular in output stages for loads connected downstream. If a fault occurs, such as for example a shortcircuit, a mechanical obstruction or the like, while these loads are operating, excessive generation of heat is to be expected. This leads to a high degree of heating, in which case temperatures occur which can lead to the output stages or the entire appliance being destroyed.
In the case of an appliance which stores information on a tape and/or reads information from a tape, such as for example a video recorder, mechanical faults can occur, for example in a drive for the storage tape, that is to say for example the video cassette. In such cases, the output stages which actuate a corresponding drive motor are heated excessively.
It is known to equip appliances in such a way that the temperature of the output stages or of the appliance is monitored, and that the respective load is no longer actuated in the case of faults of the aforementioned type in which a maximum operating temperature, also referred to as alarm temperature below, is reached.
It is also known to stipulate a lower temperature value which corresponds to a so-called warning temperature which is exceeded before the alarm temperature is reached. Above the warning temperature, the connected load is powered down from its normal operation into an idle state or from its instantaneous mode of operation into a lower mode of operation.
Problems can occur here if the fault comes from a different source or is caused by an incident. Then, despite the reduction of the mode of operation, the alarm temperature is reached. For this reason, when the warning temperature is reached the appliance must be powered down.
In a video recorder in which, for example during searching, a mechanical impedance occurs in the region of the video cassette, which can occur for example with worn or cheap cassettes, that is to say both the drive motor and other loads, such as a drum motor, are initially slowed down when the warning temperature is reached and stopped when the alarm temperature is reached. By means of this two-stage process, excessive stressing, stretching and damage to the video tape can be avoided as far as possible. However, a viewer is aware of an abrupt interruption in operation.
The object of the present invention is to develop a temperature monitoring system in an appliance in such a way that on the one hand critical operating temperatures are largely prevented from being exceeded and on the other hand the adverse effects for means or living creatures which interact with the appliance are reduced.
According to the invention, the temperature of the appliance or inside the appliance, for example in the region of the output stage, is monitored. If the temperature exceeds a first temperature value which corresponds to a temperature which is designated here as the economical temperature, the output signal of that output stage which is just actuating a load is changed in such a way that less power is fed to the load than before. Thus, the drop in power within the output stage and therefore also the generation of heat become smaller. This can load may possibly be completely actuated again, operated at reduced power, or in which case at a later time a second temperature value is reached which corresponds to a warning temperature at which only a highly reduced amount of power is fed to the respective loads. As a result, the load or loads may be switched off without damage if the alarm temperature is reached later.
The invention is based on the fact that when the load is actuated with reduced power on the one hand the warning temperature can largely be prevented from being reached and on the other hand the adverse effects for means or living creatures which interact with the appliance are greatly reduced in comparison with known systems.
For the example of the video recorder this means
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Gleim Gunter
Heizmann Friedrich
Link Hermann
Davenport Francis A.
Deutsche Thomson-Brandt GmbH
Laks Joseph J.
Sniezek Andrew L.
Tripoli Joseph S.
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