JPS63218984A - Fixing temperature controller - Google Patents

Abstract

PURPOSE:To uniformly hold a fixing roller temperature, and to obtain a stable picture quality in both of the time of copying of a single color and a multicolor, by executing the continuous copying of the minimum size as to a prescribed number of sheets or more, and thereafter, inhibiting the copying extending over some prescribed time. CONSTITUTION:Detecting signals of thermistors 47, 49 provided on a fixing roller 31 and a pressure roller 32 are sent to a CPU 52 through an A/D converter 53, and by turning ON and OFF fixing heaters 33, 34 through a solid state relay 54, a temperature is kept constant. When a single mode repeat by the minimum size, for instance, a mode of 50 sheets or more is set by an operating part 51 and copying is started, counting of a timer contained in a CPU 52 is started, and after copying has been ended, when the maximum passing paper width/multicolor copying has been selected within the time determined is accordance with the number of sheets of copying in advance, copying is inhibited. In such a way, a temperature of the fixing roller and the pressure roller can be held uniformly, and at the time of copying both of single color and multicolor, a stable picture quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fixing temperature control device, and more particularly, to a fixing temperature control device that can be applied to a multicolor recording device that can arbitrarily select multiple colors and multiple sizes. It is something.

(Prior art) The fixing temperature side of a fixing device that can be applied to various multicolor recording devices such as copying machines, laser printers, printing machines, and facsimile machines.
Conventionally, as a 4B device, for example,
A device disclosed in Japanese Patent No. 44 is known. This device proposes dividing the heater into one for heating the center of the heating roller and one for heating both ends of the heating roller, and separately controlling the energization of these heaters using a plurality of temperature detectors provided at corresponding positions. However, although this measure has the advantage of always keeping the entire peripheral surface temperature of the heating roller within the fixing temperature range, it is difficult to incorporate multiple heaters inside the heating roller, which is spatially narrow. The manufacturing cost of the heat fixing device is relatively high due to the use of a plurality of heaters.

(Purpose) The present invention was made in view of the above-mentioned disadvantages of the conventional apparatus, and its purpose is to maintain a uniform temperature of the fixing roller in a recording apparatus in which multiple colors and sizes can be arbitrarily selected. An object of the present invention is to provide a fixing temperature control device that can obtain stable image quality both during monochrome and multicolor copying.

(Structure) In order to achieve the above-mentioned object, the present invention includes a fixing means for sandwiching and conveying a recording paper in order to heat and fix a toner image on the recording paper, a heating means for heating the fixing means, and a surface of the fixing means. In a fixing temperature control device for a multicolor recording device, which is equipped with a temperature detection means for detecting and controlling temperature, and can arbitrarily select multiple colors and multiple sizes, the fixing temperature control device is equipped with a means for measuring the elapsed time after the completion of copying, This system is characterized by prohibiting copying for a certain period of time after continuous copying of a certain size or more has been made.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

FIG. 1 is a schematic diagram illustrating the main structure of a general three-color or four-color overlapping color copying machine to which the present invention is applied. In the figure, 1, 2, 3.4 are respectively 1st. Second. Third
and a fourth mirror, 5 is a lens, 6 is a three-color dividing filter consisting of a blue filter, a green filter 6b, and a red filter 6C, 7 is an optical system fan, 8 is an exposure lamp, and 9 is a photosensitive drum. 1st. Second. The third mirror and exposure lamp constitute an optical scanner. 10
1 is a cleaning roller, 1 is a static elimination charger, 12 is a static charger, 13 is an eraser, 14 is a pre-cleaning charger, 15 is a separation upper charger, 16 is a separation lower charger, 17 is a transfer drum, 18 is a pre-transfer static elimination lamp, 19 is a transfer charger, 20 is a magenta developer, 2
1 is a developing roller, 22 is a cyan developing device, 23 is a developing roller, 24 is a yellow developing device, and 25 is a developing roller.

26 is a calling roller, 27 is a paper feeding roller, 28 is a reversing roller,
29 is a cassette, and 30 is a registration roller.

Furthermore, 31 is a fixing roller, and 32 is a pressure roller.

In the color copying machine having the above configuration, in the full color copying mode, the optical scanner reciprocates three times and the zero color separation filter 6, which exposes the original image on the document table onto the photoreceptor drum 9, is rotatable. It is designed to be sequentially switched according to the three reciprocating movements of the optical scanner. For example, if Blue Filter Taro a is used first, a yellow image is visualized by the yellow (Y) developer 24, which is a complementary color. Calling roller 26, paper feeding roller 2
7. The transfer paper fed from the paper feed section consisting of a cassette 29, etc. is wrapped around the circumferential surface of the transfer drum 17 in synchronization with the photosensitive drum 9, with its tip held by a gripper (not shown), and transferred. The charger 19 transfers the yellow image described above. The toner remaining on the photosensitive drum 9 after the transfer is cleaned by a cleaning section such as a cleaning roller 10, and the residual potential is reduced to approximately 0 port by a static elimination charger 1).

The photoreceptor drum 9 uniformly charged by the charger 12 is exposed to light through the red filter 6c for the second time, and the cyan (C) developer 22, which has a complementary color relationship, visualizes the photoreceptor drum 9 on the previous transfer paper. A cyan image is transferred onto the yellow image.

Similarly, a magenta image is transferred onto a yellow image and a cyan image using a green filter 6b and a magenta (M) developing device 20, separated by a separation charge +15. Fixing roller 3
1. The image is sent to a fixing section consisting of a pressure roller 32 and the like, and is fixed by heat and pressure.

Next, in the case of monochrome copy mode, the optical scanner
The color separation filter 6 is reciprocated once for each copy, and the color separation filter 6 is switched to neutral, and the color separation filter 6 is visualized using a pre-specified developing device, transferred to the transfer paper on the transfer drum 17, fixed by the fixing unit, and discharged. Ru.

Generally, in the case of full-color copying, the thickness of the toner layer is about three times that of monochrome copying, and in order to uniformly melt the toner and improve color reproduction, it is necessary to heat the transfer paper from the back side as well. .

FIG. 2 is a schematic diagram illustrating the vicinity of the fixing section in FIG. 1 in more detail, and FIG. 3 is a perspective view showing the main part thereof. 2 and 3, 31 is a fixing roller, 32 is a pressure roller, 33 is an upper fixing heater, 34 is an upper fixing heater, 3
5 is an oil application roller, 36 is an oil supply roller, 36
a is coated felt, 37 is a paper discharge release lever, 38 is an oil sump, 39 is a cleaning blade, 40 is a cleaning roller, 41 is a static elimination brush, 42 is a scrubbing claw, 4
3 is a cleaning felt, 44 is a separating claw, 45 is a conveyor belt, 46 is a fixing entrance guide plate, 47 is a first thermistor, 48 is a temperature fuse, 49 is a second thermistor,
50 is a temperature fuse.

The fixing roller 31 is made of silicone rubber (R) on a hollow metal pipe.
TV), and an upper fixing heater 33 made of a rod-shaped heater is built-in. The surface temperature of the fixing roller 31 is set to a certain constant temperature (for example, 1
50°C). Similarly, the pressure roller 32 is a hollow metal pipe coated with Teflon (PFA) or silicone rubber (HTV), and has an upper fixing heater 34 built therein. The surface temperature of the pressure roller 32 is maintained at a certain constant temperature (for example, 150° C.) by a second thermistor 49. The first and second thermistors 47 and 49 are provided approximately at the center of the fixing and pressure rollers 31 and 32, respectively (the paper passing reference is also at the center).

Here, if the smallest size is continuously copied in monochrome mode (copying speed is three times faster than in multicolor mode where three colors are superimposed), the fixing roller 31 is difficult to absorb heat from the paper.
In addition, the temperature at both ends of the pressure roller 32 increases. This temperature increase is not noticeable in the multicolor mode because the copying speed is slow.

If multicolor copying is performed at the maximum size immediately after the temperature rises above, the hatched areas at both ends shown in graph (B) in Figure 4 will exceed the multicolor copying upper limit temperature, resulting in a pot offset phenomenon (toner on the transfer paper The transfer paper may be caught by the fixing roller 31), the transfer paper may become jammed, and the copying operation may have to be interrupted for a long time due to damage to parts around the roller. FIG. 4 is a graph showing the relationship between paper passing size and roller temperature distribution. Graph (A) in Figure 4
shows the temperature distribution under normal control conditions.

The reason that the upper limit temperature is different for multicolor copying and single color copying is because the toner thickness is, for example, three times as thick during multicolor copying, so there is a temperature difference between the toner in the upper layer and the toner in the middle or lower layer, which causes separation between the toners. This is because a phenomenon occurs and the toner becomes too soft and easily sticks to the roller.

Therefore, when the minimum size and continuous copying of single-color copies exceeds a certain fixed number (for example, 50 sheets), after the copying is completed, a timer means or the like is set to a certain fixed temperature that does not exceed the multi-color copying upper limit temperature [Figure 4 Graph (C)], when the maximum size/multicolor copying mode is selected within a certain period of time until the temperature drops, a signal indicating that copying is not possible is output. Therefore, if the graph (B) in FIG. 4 exceeds the upper limit temperature for monochrome copying, this embodiment can be applied not only to multicolor recording apparatuses but also to general black-and-white copying machines.

FIG. 5 is a graph showing the number of copies and the temperature rise at the end of the roller during monochrome copying and minimum size continuous copying. In FIG. 5, when the number of copies is N0, it takes t0 time for the temperature to drop below the upper limit for multicolor copying, but when the number of copies is N1, it takes 1.
It takes time.

FIG. 6 is a block diagram schematically showing the circuit configuration of an embodiment of the present invention, in which reference numeral 51 indicates an operation unit including a display panel (not shown);
2 is the CPU (central processing unit), 47.49 is the first
and a second thermistor, 53 is analog/digital (
A/D) converter, 54 is a solid state relay (
SSR), 33.34 is the upper and upper fixing heater, 55
is an AC power source.

A copy mode signal set by the operation unit 51 is sent to the CPU 52, which controls each copying process. Detection signals from thermistors 47 and 49 provided on the fixing roller 31 and pressure roller 32 are sent to the CPU 52 via the A/D converter 53, and the temperature is determined by turning on and off the fixing heaters 33 and 34 via the 5SR54. is held constant.

Next, a description will be given with reference to the timing chart of FIG. When copying is started with the minimum paper passing width, that is, the minimum size (for example, 85 plate), monochrome mode repeat, for example, 50 sheets or more mode, set on the operation unit 51, the CPU 52 starts counting the built-in timer T from the start of copying. let it start,
After copying is completed, only if the maximum paper width (for example, A3 size) and multicolor copying are selected within a predetermined time according to the number of copies, the "Ready to copy" message will be displayed on the display panel (not shown). Instead of displaying "Please wait", copying operations are prohibited. In other modes and after a certain amount of time has elapsed, the message ``Ready to copy'' is displayed.

Next, fixing warm-up control will be explained with reference to the flowchart of FIG. Set temperature XI'C of fixing roller 31 and pressure roller 32 and their detected temperature Y
Determine whether 1°C is YI≧X. Yl≧X
If it is not I, a warm-up operation is performed, the copy enable signal is turned off, "Copy ready" is turned off, "Please wait" is lit, and the fixing heaters 33 and 34 are turned on.

Next, it is determined again that Yl ≧X, and if Y≧X1, the fixing heaters 33 and 34 are turned off, the copy enable signal is turned on, and
The "Please wait" display is turned off, the "Ready to copy" display is turned on, warm-up is completed, and the roller temperature XI°C is controlled.

Next, a copying operation in a multicolor recording apparatus embodying the present invention will be explained with reference to the flowchart of FIG.

The copy mode is set, copying is started, and after the copying process is completed, the paper size and number of copies are read out. If the paper size is 85 plates, multicolor copying is not performed, and the number of copies is not N≧50, the process moves to step (2). If the number of copies is N≧50, turn on the copy prohibition timer T and start counting the timer counter CO8 built into the CPU 52.0 Next, reset the copy mode, and if the paper size is A3 and the copy is not multicolor, The flow moves to (2), the timer T is turned off, the counter CO6 is cleared, and the flow moves to (2). In the case of multicolor copying, it is determined whether COt≧t, and if Co1≧t, the timer T is turned off, the counter CO+ is cleared, and the process moves to step (2). If CoI≧t is not the case, reset the copy mode and repeat the following flow. If not, go to the flow of ■, turn off the copy enable signal, and click "Please wait."
Turn on the signal and repeat the following flow.

FIG. 10 is a block diagram illustrating the copying process of the multicolor recording apparatus in this embodiment from start to finish. However, since the flow of each process is obvious in this figure, further explanation will be omitted.

According to the above embodiment, copying is prohibited when the maximum size/multicolor copying mode is selected, and the prohibited time can be made variable depending on the number of copies. Further, by providing the first thermistor in the fixing means that directly contacts the toner image and the second thermistor near the end of the maximum paper passing size, the second thermistor reaches a certain temperature and the maximum paper passing size is reached. and when multicolor mode is selected, copying can be prohibited.

(Effects) As described above, according to the present invention, there is a fixing means that pinches and conveys the recording paper in order to heat and fix the toner image on the recording paper, a heating means that heats the fixing means, and a surface of the fixing means. In a fixing temperature control device for a multicolor recording device, which is equipped with a temperature detection means for detecting and controlling temperature, and can arbitrarily select multiple colors and multiple sizes, the fixing temperature control device is equipped with a means for measuring the elapsed time after the completion of copying, After making continuous copies of a certain size or more, copying is prohibited for a certain period of time, so the temperature of the fixing roller and pressure roller can be maintained uniformly, preventing hot offsets, jams, etc. It is possible to provide a fixing temperature control device that can prevent troubles and provide stable image quality both in monochrome and multicolor images.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the main structure of a general three-color or four-color overlapping color copying machine to which the present invention is applied, and FIG. 2 is a schematic diagram illustrating the vicinity of the fixing section in FIG. 1 in more detail. , FIG. 3 is a perspective view showing the main part of FIG. 2, FIG. 4 is a graph showing the relationship between paper passing size and roller temperature distribution, and FIG. A graph showing the temperature rise at the end of the roller, FIG. 6 is a block diagram schematically showing the circuit configuration of an embodiment of the present invention, FIG. 7 is a timing chart for controlling the copying process, and FIG. 8 is a diagram showing the fixing worm. FIG. 9 is a flowchart for explaining the up control, FIG. 9 is a flowchart for explaining the entire copying operation, and FIG. 10 is a block diagram for explaining the copying process from start to finish. 31... Fixing roller, 32... Pressure roller, 33...
...Top fixing heater, 34...Top fixing heater, 47...
・First thermistor, 49...Second thermistor, 5
1...Operation unit, 52...CPU, T...Timer,
coI...Counter. Figure 1 Figure 3 Figure 4 Figure 5 District 10

Claims (4)

[Claims] (1) A fixing device that clamps and conveys the recording paper in order to heat and fix the toner image on the recording paper, a heating device that heats the fixing device, and a temperature detection device that detects and controls the surface temperature of the fixing device. , a fixing temperature control device in a multicolor recording device that can arbitrarily select multiple colors and multiple sizes, is equipped with a means for measuring the elapsed time after the completion of copying, and after a certain number of consecutive copies of the minimum size have been made. A fixing temperature control device characterized in that copying is prohibited for a certain period of time. (2) The fixing temperature control device according to claim (1), wherein the copying prohibition is performed when a maximum size and multicolor copying mode is selected. (3) The fixing temperature control device according to claim (1), wherein the copy prohibition can be made variable for a prohibition time depending on the number of copies. (4) The fixing means that comes into direct contact with the toner image has a first thermistor that detects and controls the surface temperature of the fixing means at approximately the center in the longitudinal direction thereof, and at the end of the largest paper passing size among the multiple sizes. Claims characterized in that a second thermistor is provided nearby, and when the second thermistor reaches a certain temperature and the maximum paper passing size and multicolor mode are selected, copying is prohibited. The fixing temperature control device according to item (1).