JPH02211471A - Fixing device for copying machine or the like - Google Patents

Abstract

PURPOSE:To improve the working efficiency and economy of a copying machine, etc., by interrupting copying when the temp. falls below the fixing assurance temp. with the colors, kinds, etc., of the toners to be handled and executing the copying and fixing of an adequate number of copies. CONSTITUTION:A CPU 24 makes sampling operation by the clock period of a clock generating circuit 27. The colors and kinds of the toners are detected from a detecting circuit 21 and are inputted to the CPU 24. The surface temp. of a fixing roller 2 of this time is detected from a temp. detecting circuit 22 and is converted by an A/D converting circuit 2 to a digital value which is inputted to the CPU 24. The CPU 24 controls the fixing assurance temp. of a fixing heater circuit 26 by the colors and kinds of the toners built in a ROM 25 and turns a heater 1 on/off. Printing is stopped and is held interrupted until the heater 1 is turned on again and the fixing roller 2 attains the control temp. of the fixing part when the temp. of the fixing roller 2 lowers if the fixing roller 2 has the quantity of heat applied by the heater 1 large than the quantity of heat required for fixing, i.e. at the time of, for example, continuous printing, in the case of starting the print copying at above the fixing assurance temp.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a copier equipped with a heat roller fixing device, and changes the toner fixing guarantee temperature at which continuous copying is interrupted depending on two types of toner being handled. Regarding the fixing device that can be used.

(Prior art) Figure 4 shows a heat roller fixing device for a copying machine, etc.
The fixing roller 2 heated to the fixing temperature by is rotated in the direction of the arrow. On the other hand, a pressure roller 3 rotating in the direction of the arrow with a constant contact pressure on the fixing roller 2 causes the toner 5 to be
The copy paper 4 to which toner is attached is inserted between the fixing roller 2 and the toner 5 is fused and fixed to the copy paper 4.

In such a fixing device, when an attempt is made to increase the copying speed, the amount of heat taken by the copy paper 4 from the fixing roller 2 increases in proportion to the increase, so that the surface temperature of the fixing roller 2 decreases. In order to prevent this, it is possible to increase the power given to the heater, but since this is generally not possible with a commercial power source, the surface temperature of the fixing roller 2 is usually detected.
If the temperature falls below a specified value, copying is interrupted and the surface temperature is allowed to recover.

(Problem to be Solved by the Invention) FIG. 1 shows the temperature change (vertical axis) of the fixing roller 2 with respect to the number of continuous copies (horizontal axis).

In the figure, T is the fixing unit control temperature, T1 is the guaranteed fixing temperature for black toner, T2 is blue toner, and T3 is each guaranteed fixing temperature for red toner. represents the number of copies Y, and X1 to X2 represent the number of copies Y8.

As can be seen from this characteristic curve of the number of copies and temperature change, the conventional fixing roller temporarily stops copying and controls the fixing unit when the temperature reaches a certain temperature, usually the guaranteed fixing temperature for black toner T□. I was trying to wait until the temperature returned to T.

However, in recent copying machines, etc., in addition to black toner, blue toner and red toner are used in the same copying machine, so when using these blue and red toners, the guaranteed fixing temperature of black toner Relying only on T1 causes the following problems.

As shown in the figure, the guaranteed fixing temperature T2 of the blue toner is higher than T, and the guaranteed fixing temperature T3 of the red toner is lower than T1. For this reason, when using red toner, for example, fixing can be guaranteed up to temperature T, but the process is interrupted at temperature T1, and therefore, the process is interrupted when the number of copies is Y□ (x1 to X).

In addition, when using blue toner, although temperature T2 is the limit at which fixation can be guaranteed, it will not be interrupted unless the temperature drops below that, T It turns out.

The present invention eliminates the above-mentioned problems, and improves efficiency and economy by suspending copying when the temperature drops below the guaranteed fixing temperature of each toner, and by adjusting the number of copies and fixing according to each toner. The purpose is to measure.

(Structure and operation) In order to achieve the above-mentioned object, the present invention has the following features: When the surface temperature of the fixing roller falls below the guaranteed fixing temperature during continuous copying,
In the fixing device that temporarily interrupts copying, the guaranteed fixing temperature of the toner at which copying is interrupted is changed depending on nine types of toner colors handled.

According to the present invention, depending on the nine types of toner colors to be handled,
Since the setting of each toner's guaranteed fixing temperature is changed, copying is done when the time to interrupt copying is appropriate.As a result, the copying machine can operate efficiently with the optimum number of copies and high-quality fixing. It is also economical.

(Embodiment) As shown in the graph of the number of copies vs. toner guaranteed fixing temperature in FIG. T
, is set.

FIG. 2 shows an embodiment of the fixing guarantee temperature setting circuit.

In the figure, 21 is a detection circuit for detecting one type of toner color, 22 is a temperature detection circuit for detecting the surface temperature of the fixing roller (FIG. 4, 2), and 23 is the temperature detection circuit 2.
An A/D conversion circuit that converts the surface temperature of the fixing roller detected in step 2 into a digital value.

24 is a CPU that controls the entire operation of the copying machine; 25 is a ROM that stores data on the guaranteed fixing temperature of each toner;
6 is a fixing heater circuit, and 27 is a clock generation circuit that is the basis of the operation of the copying machine.

This is determined by the clock cycle of the clock generation circuit 27.
The PU 24 performs a sampling operation, detects one type of toner color from the detection circuit 21, inputs it to the CPU 24, detects the surface temperature of the fixing roller 2 at that time from the temperature detection circuit 22, and converts it into digital data using the A/D conversion circuit 23. It is converted into a value and inputted to the CPU 24.

The CPU 24 determines the guaranteed fixing temperature of the fixing heater circuit 26 (T in FIG.
1. T2. T3) and set heater 1 to 0N10F.
F.

FIG. 3 is an operation flowchart according to FIGS. 1 and 2 above. When the power switch of the copying machine is turned on, the heater 1
is turned on (S□), printing and copying cannot be performed until the temperature of the fixing roller 2 reaches the fixing unit control temperature T (Fig. 1) (S, , S, l).

Then, when the temperature of the fixing roller 2 rises and reaches the fixing unit control temperature T, the print copy is OK (S
3). When print copying is actually started at a temperature higher than the guaranteed fixing temperature (S4) (S,), the fixing roller 2 is heated as shown in FIG. When the temperature of the fixing roller 2 becomes low (S,), printing is stopped (St)L, and the heater 1 is turned ON (S□) again until the fixing roller 2 reaches the fixing unit control temperature T.

By the way, in the past, as mentioned above, the guaranteed fixing temperature was set at the temperature 'r1 of black toner, but in the present invention, in the case of blue toner, the guaranteed fixing temperature T2 is set higher than T1, and the temperature is adjusted accordingly. To prevent 78 sheets of defective fixing between T and T2. Further, in the case of red toner, the fixing guarantee temperature is set lower than T1 to enable printing of Y square sheets at a temperature between T1 and T1.

(Effects of the Invention) As described above, in the present invention, the fixing guarantee temperature can be changed depending on the two types of toner colors, so it is possible to achieve an optimum number of print copies and high-quality fixing. Therefore, it is efficient and economical.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the relationship between the guaranteed fixing temperature of each toner and the number of copies, Fig. 2 is a circuit diagram of an embodiment of the present invention, and Fig. 3
The figure is an operation flowchart of the present invention, and FIG. 4 is a diagram showing the configuration of the fixing device. 1... Heater, 2... Fixing roller, 3.
...Pressure roller, 4...Copy paper, 5...
Toner 21... Two types of toner color detection circuits, 2
2...Fixing roller surface temperature detection circuit, 23...A
/D conversion circuit. 24... CPU, 25... ROM, 26... Fixing heater circuit, 27... Clock generation circuit.

Claims (1)

[Claims] During continuous copying, when the surface temperature of the fixing roller drops below the guaranteed fixing temperature, the fixing device temporarily suspends copying. Depending on the color, type, etc. of the toner being handled, the guaranteed fixing temperature of the toner at which the copying is suspended is changed. A fixing device for a copying machine, etc., characterized in that: