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Browse Prior Art Database

Heat Controller for Small Copier

IP.com Disclosure Number: IPCOM000050275D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Dodge, JH: AUTHOR [+2]

Abstract

The idea described is an economical heat controller especially suitable for small low cost copiers. Continuous use can increase excessively the internal temperature of a machine designed for intermittent use. This scheme is a substitute for temperature sensors and cooling devices. The basic idea uses programmed digital integration with time recovery. See original for flowchart (Another example of a digital integrator with time recovery is shown in U.S. Patent 4,145,743, which discloses a noise threshold level generator.)

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Heat Controller for Small Copier

The idea described is an economical heat controller especially suitable for small low cost copiers. Continuous use can increase excessively the internal temperature of a machine designed for intermittent use. This scheme is a substitute for temperature sensors and cooling devices. The basic idea uses programmed digital integration with time recovery. See original for flowchart (Another example of a digital integrator with time recovery is shown in U.S. Patent 4,145,743, which discloses a noise threshold level generator.)

Fig. 1 is an analog circuit for explaining the principle. A switch (SW) is closed for a given period of time for each copy made, or it can be closed during the time period a copy job is in progress.

The current supplied through R1 is integrated by capacitor C as is the current supplied through R2 by a constant voltage. The integrator's output signal, Vo, is (V1/R1- V2/R2)t/C. If the switch SW is not operated for long intervals, the output voltage Vo will reach a lower limit, and when the value of Vo is less than some preset low limit (LOW REF), a switch S, shown as an IGFET, discharges the capacitor C to initialize the system. If switch SW is operated for a significant length of time, the output voltage Vo will rise above an upper limit (HIGH REF) and halt the machine. Two upper limits can be used as shown in the digital example.

Fig. 2 is a digital circuit implementation of the invention. A counter is incremented...