Typewriting machines – Safety switch or condition-responsive-cutoff switch for...
Patent
1994-04-15
1995-09-12
Wiecking, David A.
Typewriting machines
Safety switch or condition-responsive-cutoff switch for...
400 88, 320 43, 364707, B41J 2938, H02J 700
Patent
active
054492386
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
A recording device formed as a thermal printer is known from DE-PS 32 02 185. Such a recording device demonstrates a high peak power requirement during the recording process. To cover this peak power requirement, providing a corresponding high-performance power pack is possible. However, such a high-performance component would significantly increase the overall costs of the recording device. If accumulators, which are perfectly capable of giving off large amounts of power for a short time, are used in the known thermal printer as a power source, the number of possible recording processes is limited by the lifetime (i.e. the capacity) of the accumulators. To maintain uniform printing quality with a decreasing performance capacity of the accumulators, the printing parameters must be adapted. Such an adaptation takes place in the thermal printer known from DE-PS 32 02 185 during the period when its heating elements are kept on. However, doing so has a disadvantageous effect on the printing speed.
When using rechargeable accumulators, a discharge beyond a certain charge state (i.e. complete discharge or deep discharge) must also be avoided, otherwise damage or destruction of these accumulators may result. The lifetime, which is limited by the number of charging cycles and the useful capacity of the accumulators, is determined to a significant extent by the discharge speed. Therefore, in a recording device powered by rechargeable accumulators, efficient use of small amounts of power is necessary for reasons of economic efficiency and recording capacity.
The present invention is therefore based on the task of creating a method for operating a recording device powered by at least one rechargeable accumulator wherein the greatest possible number of recording processes can be carried out and wherein deep discharge of the rechargeable accumulators is reliably avoided.
SUMMARY OF THE INVENTION
The above mentioned task is accomplished, according to the present invention, with a method for operating a recording device powered by at least one rechargeable accumulator. The recording device includes a charger which can be connected and disconnected, a control, a main switch for start-up and shut-down of the recording device, and at least one electric switch for separating the recording device from the accumulator. The recording device is placed into a stand-by state or into an operative state after start-up, if the state of charge of the accumulator is above a limit sufficient for a recording process. The recording device is placed into the stand-by state in which the power consumption of the control is reduced relative to the operative state and the accumulator is charged, if the state of charge of the accumulator is below the limit and the charger is connected. The recording device is placed into the operative state from the stand-by state when an activation signal occurs, if the state of charge of the accumulator is above the limit. The recording device is placed into the stand-by state from the operative state when a deactivation signal occurs. Finally, the recording device is placed in the electrically shut off state by the electric switch, when the state of charge of the accumulator is below the limit and the charger is shut off.
Placeing the control into power-saving mode (i.e., stand-by state) is possible, for example, in that semiconductor elements of the control are switched over to the tri-state mode. In a correspondingly structured processor which monitors the control, the cycle frequency can be reduced to lower the power consumption. An example of such a processor is the DMOS processor M 68000 described in the essay "Apples Tragbarer: Spat kommt er, doch er kommt [Apple's Portable: Better Late than Never]" in the Frankfurter Allgemeine Zeitung on Sep. 26, 1989, page T1.
When the recording device is started up, it is first placed into the operative state if the accumulator has a sufficient charge. From this state, if no recording process takes place within a comparatively short
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Al-Khatib Mohamed
Drees Friedrich-Wilhelm
Eiler Walter
Pekruhn Wolfgang
Pham Ngoc Q.
Eastman Kodak Company
Kelley Steven S.
Wiecking David A.
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