An image forming apparatus

Assignee: Kyocera Mita Industrial Co Ltd

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Filing: 1992-03-11

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Granted: —

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Expires: 2012-03-11

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Abstract

Abstract An image forming apparatus comprises an image forming unit for forming and transferring an image of a document to a copy sheet, a fixing unit (19) including a fixing roller (191) for fixing the document image to the sheet while transporting the sheet, a heater (193) for the fixing roller, and a heater control unit (34) for turning the heater on and off at specified timings so as to establish and maintain the temperature of the fixing roller in a predetermined range whose upper limit is a fixing temperature. The copy sheet heated by the fixing roller has a temperature of about the predetermined fixing temperature while in transport, whereby the image transferred to the copy sheet is fixed thereto. A control unit (30) acts on the heater control unit (34) so that it controls the heater over the period during which a copying operation is completed. The heater control unit on-off controls the heater only during the copying operation. Accordingly, power consumed by the heater is reduced and an unwanted temperature increase within the apparatus can be avoided.

Inventors

👤 Junichi Hirobe
👤 Masakutsu Akashi
👤 Masahiko Kobayashi
👤 Tsutomu Sugaya

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-09 15:39

CPC Classifications

G; G03; G03G; G03G15/00; G03G15/20; G03G15/2003; G03G15/2014; G03G15/2039; G03G15/205

Claims Analysis

Total Claims: 8

Claim 1

Independent Claim 143 words

An image forming apparatus comprising: image forming means for forming and transferring an image of a document to a copy sheet; fixing means including: a fixing roller for fixing the document image to the copy sheet while transporting it; heater means for heating the fixing roller; heater control means for turning on and off the heater means at specified timings so as to increase and maintain temperature of the fixing roller to and in a predetermined steady-state temperature range whose upper limit is a fixing temperature; and the copy sheet being heated by the fixing roller having temperature of about the predetermined fixing temperature while transported, whereby the document image transferred to the copy sheet is fixed thereto; and control means for controlling the heater control means to control the heater means within a copying period during which a copying operation is completed.

Claim 2

Dependent Claim 27 words

An image forming apparatus as defined in claim 1 wherein the control means starts controlling the heater control means before driving of the fixing roller is started.

Claim 3

Dependent Claim 66 words

An image forming apparatus as defined in claim 1 further comprising designation means for designating a control stop timing at which the heater control means stops controlling the temperature of the fixing roller before a trailing end of the copy sheet passes the fixing roller by a predetermined period wherein the control means stops controlling the heater control means when the control stop timing is designated.

Claim 4

Dependent Claim 33 words

An image forming apparatus as defined in claim 3 wherein the designation means is timer means which designates the control stop timing upon measuring a preset period following start of the copying operation.

Claim 5

Dependent Claim 57 words

An image forming apparatus as defined in claim 3 wherein the designation means is sensor means disposed away from the fixing roller to a more downstream side by a distance shorter than a length of the copy sheet in a sheet transport direction, the sensor means being adapted for detecting a leading end of the copy sheet.

Claim 6

Dependent Claim 125 words

An image forming apparatus as defined in claim 1 further comprising: temperature detector means for detecting temperature of the fixing roller when the heater means is first turned on during the copying operation; calculation means for calculating, based on the temperature detected by the temperature detector means, a transient period during which the heater means is kept on after first turned on in the copying operation, the transient period being such that the temperature of the fixing roller increasing even after the end of the transient period is peaked at the fixing temperature; wherein the heater control means keeps the heater means on during the transient period calculated by the calculation means to increase the temperature of the fixing roller to the predetermined fixing temperature.

Claim 7

Dependent Claim 66 words

An image forming apparatus as defined in claim 6 further comprising memory means for storing in advance a conversion table defining relationship between the temperature of the fixing roller detected by the temperature detector means and corresponding transient period wherein the calculation means determines the transient period based on the detection result of the temperature detector means using the conversion table stored in the memory means.

Claim 8

Dependent Claim 101 words

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