JPH0363684A - Thermal fixing device - Google Patents

Abstract

PURPOSE:To execute fixing with remaining heaters even if a disconnection arises by outputting the information on a paper size at which thermal fixing is possible with the information on the heater disconnection. CONSTITUTION:A command to permit the copying of the paper of the size to use only the main heater 111 is outputted to a paper size supplying means 40 when the detection signal of the disconnection of the sub-heater 112 is inputted via an I/O interface 30 to a CPU 31. The means 40 locks the paper of the prohibited size of paper size selection keys to prohibit the selection of the keys. The fixing of the paper of the range where the fixing by the remaining heaters is possible is executed in such a manner even if a part of the heaters is disconnected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a thermal fixing device that is equipped with a plurality of heaters and heats the selected heaters according to various paper sizes to thermally fix a toner image on the paper. Regarding.

[Prior Art] Conventionally, as shown in FIG. 2, a heat fixing device for a copying machine, for example, has a heat roller l equipped with a heater 11 inside, and a pressure roller 2 in contact with the heat roller l. The toner is thermally fixed to the paper 5 while the paper 5 having the toner image transferred thereon passes between the heat roller 1 and the pressure roller 2 (Japanese Patent Laid-Open No. 57-158866). In the figure, 3 is a thermistor, and 4 is a temperature control means for appropriately controlling the heater 11 based on temperature data from the thermistor 3. FIG. 3 is a diagram showing details of the heater 11, in which the first heater 11+ and the second heater 112 are wired in parallel. The first heater 11+ covers the W2 area on the right side as shown in the figure, and the second heater 112 covers the W3 area on the left side as shown in the figure. It covers the entire area W1. Therefore, in FIG. 2, in the case of B4 vertical feeding and B5 horizontal feeding, heat fixing is performed within the range of W2 in the figure, so heating by only the first heater 11+ is sufficient;
In the case of horizontal feeding, heat fixation is performed within the range of Wl in the figure, so
The second heater 112 is also heated.

[Problems to be Solved by the Invention] For example, when the first heater 112 is disconnected, the conventional heat fixing device described above treats this as an abnormality and stops copying altogether.

However, if only the second heater l12 is disconnected, as is clear from the above, B4 vertical feeding and B5 horizontal feeding are possible by the first heater 11+. However, conventionally, copying has been completely stopped.

The present invention aims to solve the problems of the prior art.

[Means for Solving the Problems] The present invention provides a thermal fixing device that includes a plurality of heaters, selects and heats the heaters according to various paper sizes, and thermally fixes a toner image on the paper. a wire breakage detection means for detecting a wire breakage, and outputs size information of paper that can or cannot be thermally fixed based on the information detected by the wire breakage detection means, and outputs wire breakage information if there is a wire breakage. This is a heat fixing device equipped with a determining means.

[Function] The present invention provides a thermal fixing device that is equipped with a plurality of heaters and thermally fixes a toner image on the paper by selecting and heating the heaters according to various paper sizes. The determination means outputs size information of the paper that can or cannot be thermally fixed based on the information detected by the wire breakage detection means, and also outputs wire breakage information if there is a wire breakage.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of a thermal fixing device according to the present invention.

In the figure, the main heater 111 is as shown in FIG.
A heater that covers the W2 area, sub-heater 1
12 is a heater that covers the W3 area. This main heater 11+ is connected to a power source 33 via a temperature fuse 26, a silicon risk switch 5SR28, and a relay switch 32.

Further, the sub-heater 112 is connected to a power source 33 via a temperature fuse 27, a silicon risk switch 5SR29, and a relay switch 32.

Furthermore, the sirisk switch 5SR2B, 29 is
It is connected to a CPU (central processing unit) 31 via an I10 interface 3o.

Furthermore, thermistors 24 and 25 are provided in the main heater 111 and the sub-heater 112, respectively, to detect the heat generation state of the respective heaters 11+ and 112. These thermistors 24 and 25 are also connected to a CPU (central processing unit) 31 via an I10 interface 30.

Further, a first current sensor 22 is connected to the main heater 11+ as an example of a disconnection detection means for detecting a current flowing therein, and a first current sensor 22 is connected to the sub-heater 112 as an example of a disconnection detection means. A second current sensor 23 that detects current is connected. The first and second current sensors 22 and 23 are also connected to the CPU (central processing unit) 3 via the I10 interface 30.
Connected to 1.

Furthermore, 34 and 35 shown at the bottom of the figure are B4 sheets supplied from the paper supply means 40 and to which a toner image is transferred by the transfer device. It is paper such as A3. The CPU 31 is a means for implementing various means such as a determination means as described below in a software manner using storage means such as RAM and ROM.

Next, the operation of the heat fixing device of the present invention will be explained in accordance with the above embodiment.

During normal copying, the CPU 31 instructs the paper supply means 4o to supply paper of the paper size selected by the paper size selection key on the operation panel. Paper supply means 4
In response to this command, the printer o sends, for example, B4 or A3 size paper 34,35 to the transfer site. Then, the toner image on the photoreceptor surface is transferred onto the paper 34, 35 by the transfer device. The paper onto which the toner image has been transferred is conveyed to a heat fixing device, and as shown in FIG.
, and further heated by the sub-heater 112, and the toner image is fixed on the paper.

By the way, let us now assume that the sub-heater 112 is disconnected. The disconnection is detected by the second current sensor 23. The detection signal is inputted to the CPU 31 via the I10 interface 30. On the other hand, the first current sensor 2
From 2 onwards, the non-disconnection signal is manually generated. Based on these signals, the CPU 3 determines that the main heater 11+ is not disconnected, but the sub-heater 112 is disconnected. and,
Allows copying of paper of a size used only by main heater 11+, and not only main heater 11+ but also sub heater 1
12 also outputs information prohibiting copying of paper of the required size to the paper supply means 40, for example. The paper supply means 40 receives the command and supplies only the permitted paper size. For example, among the paper size selection keys on the operation panel, the selection keys for prohibited paper sizes are locked so that they cannot be selected. Also, along with that,
It also outputs a signal indicating that the wire has been disconnected. Using that signal, for example, depending on the liquid crystal or LED display element on the operation panel,
A warning may be displayed to indicate the disconnection.

If the main heater 11+ is also disconnected, feeding of all sheets is prohibited.

Even when only the main heater 11+ is disconnected, feeding of all sheets is prohibited.

In addition to this judgment command function, the CPU 3t also has the following functions:
Based on the temperature signals from the thermistors 24 and 25, the thyrisk switches 5SR28 and 29 are turned on and off in order to control the heating state of the heater to a predetermined temperature.

Note that the heaters that are allowed are not limited to those in the above example, but depending on the number of heaters, their arrangement, the position where the paper is fed, etc., the heaters that are allowed in the event of a disconnection may be Needless to say, it will be selected.

Further, as the wire breakage detection means, not only the current sensor but also other known wire breakage detection means may be used.

In the above embodiment, a microcomputer is used as the determination means, but a dedicated discrete circuit may be used for such determination means.

[Effects of the Invention] As described above, the present invention detects a heater disconnection, and based on the detected information, outputs information on the size of paper that can or cannot be heat-fixed, and also detects the disconnection of the heater. In this case, disconnection information is output, which is convenient because even if some heaters are disconnected, it is possible to fix a sheet of paper size within the range that can be fixed using the remaining heaters.

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram showing an embodiment of the heat fixing device according to the present invention, FIG. 2 is a perspective view of the heat fixing device, and FIG. 3 is a front view of the heater of the heat fixing device. be. 11, 11+, 112◆◆・Heater 22.23◆◆・Current sensor (disconnection detection means) 31
...CPU (judgment means) Figure 2

Claims (1)

[Claims] In a thermal fixing device that includes a plurality of heaters and thermally fixes a toner image on paper by selecting and heating the heaters according to various paper sizes, a wire breakage detection means for detecting a wire breakage in the heater, and a wire breakage detection means for detecting the wire breakage. A thermal fixing device characterized by comprising: a determination device that outputs information on the size of paper that can or cannot be heat-fixed based on the information detected by the device, and also outputs disconnection information if there is a disconnection. Device.