JPS5981668A - Heat roller fixing device - Google Patents

Abstract

PURPOSE:To utilize consumed electric power effectively and to obtain excellent fixing by performing high/low switching of electric power supplied to a pressure roller according to a signal for controlling the surface temperature of a heat roller. CONSTITUTION:The heat roller 1 and pressure roller 4 incorporate heaters H1 and H2 respectively and the triac TRC of the heater H1 is turned on and off by a signal from a temperature detecting element TH to hold the surface temperature of the heat roller 1 constant. A normally open contact RA-1 is closed and is made to heat the pressure roller 4 for warming-up operation wherein the heat roller rises in temperature up to a prescribed value. Then, a normally closed contact RA-2 is closed and is made to impress the secondary-side stepped-down voltage of a transformer TR, reducing power consumption. Thus, the consumed power of a copying machine, etc., is utilized effectively to heat the heat roller and quantity of heat from the heat roller surface to the pressure roller is reduced to use it effectively for toner fusion, thereby improving the fixing performance.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a heated roller fixing device for fixing unfused toner images to copy paper.

2. Description of the Related Art Generally, in copying machines and the like, a heat roller fixing device is widely used, which is composed of a candy roller having a built-in heating means and a pressure roller that rotates in pressure contact with the heat roller.

However, this type of heat roller fixing device has the following disadvantages.

When the power is turned on using the main switch, the surface flow rate of the heating roller increases by turning on a heating means, for example, a heater, but the surface temperature of the pressure roller hardly rises. This is because the pressure roller generally has a thicker rubber layer than the heating roller, so the amount of heat applied from the heating roller surface to the pressure roller surface through the contact portion is insufficient.

From this, the surface temperature of the heating roller can be set ji! When warm-up is completed and the copying operation is started to perform continuous copying, the heat on the surface of the heating roller is consumed to raise the surface temperature of the pressure roller and is absorbed by the copying paper to a large extent. The surface temperature of the copy paper drops to a large degree, and the heat required to melt the toner on the copy paper is insufficient by one degree, resulting in a printing failure.

This phenomenon is most noticeable when copying first thing in the morning, especially when continuous copying is performed.

In order to eliminate such inconveniences, it is conceivable to provide the pressure roller with a heating means to increase the temperature of the surface of the heating roller and to reduce the amount of heat taken away from the surface of the heating roller to the surface of the pressure roller. . However, recently there is a need to save power even in copying machines, and there is a limit to the overall power consumption. Naturally, there is also a limit to the amount of power that can be consumed by the heating means for the heating roller and the pressure roller.

Furthermore, since the heating roller directly contacts the unfixed toner on the copy paper, the surface temperature of the heating roller must be set to a temperature that provides a sufficient amount of heat to melt the toner. This requires more power to be consumed than the heating means for the pressure roller. Therefore, if the power that can be consumed by the heating means of the pressure roller is reduced, or if the power given to the heating means of the pressure roller is small, the rubber thickness of the pressure roller is greater than the rubber thickness of the heating roller or the coating layer. Because of the large size and poor thermal response, the surface temperature of the pressure roller does not rise to an extent that does not adversely affect the heating roller surface 61□ (i.e., remove heat from the heating roller surface).

On the other hand, in order to prevent the surface temperature of the pressure roller from having an adverse effect on the surface temperature of the heating roller, is it possible to ignore the power consumption and make the heating means of the pressure roller consume more power? If the surface temperature of the pressure roller is too high, the surface of the heating roller will be heated excessively, causing offset.

Therefore, it is necessary to provide a temperature control means for the pressure roller to set the surface temperature of the pressure roller to a predetermined temperature, which is undesirable because the structure of the heat roller fixing device becomes complicated and costs increase.

Purpose The present invention has been made in view of the above-mentioned disadvantages, and its purpose is to provide a heat roller fixing device that can effectively utilize the consumption of copying machines, etc. and obtain good fixing performance. be.

SUMMARY OF THE INVENTION In order to achieve the object described in item 1, the present invention provides a heating roller having a built-in heating means, a pressure roller that is pressed against the heating roller and having a built-in heating means, a rotation driving means for both rollers, and a heating roller having a built-in heating means. In a heat roller fixing device, the heat roller fixing device is provided with a control means for controlling the surface temperature of the roller and outputting a signal when the surface of the heat roller reaches a predetermined temperature after turning on a main switch, and supplying the pressure roller to the heating means. A control means is provided for switching the power from high power to low power according to the signal.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an oil coating type heat roller fixing device to which the present invention is applied.

The heating roller (1) has a core metal (2) made of iron alloy such as stainless steel, aluminum, etc. The outer periphery gls of the heating roller (1) is coated with a thin silicone rubber or Teflon layer (3), and a heater (mountain) is installed inside to heat the surface of the heating roller. ) within if#c L. The pressure roller (4) is made of a core metal (5) made of the same 14 materials as the core metal (2), with a silicone rubber layer (6) bonded to the outer circumferential surface of the core metal (5), and a pressure roller inside. (4) Built-in heater (H2) that heats the surface. The heating roller (1) is rotated in the direction of the arrow by the drive motor and the ladle! Iil,! be moved.

The pressure roller (4) rotates in accordance with this rotation.

Silicone oil is supplied to the surface of the heating roller (1) to prevent offset, or this is applied to the surface of the heating roller (1).
The adder 11-roller (4) rotates as a result of the drive rotation of 1).
) side, silicone oil is supplied and applied to the pressure roller (4) by the oil supply application roller (7) which is in pressure contact with the pressure roller (4) and rotates driven by the pressure roller (4), and the leveling roller (
8) After smoothing it evenly, heat roller [ ] ) ;/
Supplied to the J side. The operation of the drive motor is
The drive control circuit (11) of the i1 system (9) serves as a secondary side,
;・Δl, Qill motor) operating time is determined by the control system (
9) is controlled by the timer circuit (I2).

In addition, as the temperature rises, the surface of the heating roller (1)
), the temperature sensing element (TH) detects the surface temperature of the heating roller (1), and transmits a detection signal to the temperature control circuit (10). The /M degree control circuit (]0) controls the heater (fh) based on this detection signal so as to constantly maintain the surface temperature of the heating roller (1) at the set temperature (200° C. in this embodiment).

Now, when the power is turned on using the main switch (not shown) of the electronic copying machine, the heater (1-11) and the heater (1-1
F2) and J are turned on to heat the heating roller (1) and pressure roller (4), respectively. During warm-up, a printed circuit (not shown in FIG. 1) for controlling the copying operation is cut off so that the copying operation cannot be started. When the surface temperature (of the heating roller) reaches the set temperature, that is, when the warm-up is completed, the printed circuit is unblocked by the warm-up completion signal, and the copying operation can be started.

On the other hand, the pressure roller (4) is heated by the heater (Hl) during the warm-up, or is the pressure roller (4) heated by the heater (Ilz)?
The electric power supplied to the electric power source is controlled to be switched from high electric power to low electric power by the warm-up completion signal 7j1,
This control will be explained in detail below.

FIG. 2 is a circuit diagram for controlling the temperature of the heater (output) and controlling the switching of the power supplied to the heater (Ilz).

Heater (Hl) and heater (Hl) are alternating current power supply (AC)
It is configured to operate by receiving power supply from.

First, a bidirectional thyristoric (hereinafter referred to as TRIAC) (TRC) is used for switching the heater (!(1)), and the gate of the TRIAC ('11ζC) is connected to the control signal of the temperature control circuit (10). In other words, when the detected temperature of the temperature sensing element (TI()) is in a region lower than the set temperature, the triac ('n
tc ) is turned on, the heater ([b) lights up, and if the detection temperature is higher than the set temperature, the triac ('nt
c) is not turned on, and the heater (Hl) stops heating (9V).

The heating roller (1) is heated by repeating this operation with the skewer.
Vortex control is performed to keep the surface temperature constant.

Next, regarding the heater (Hz), there is a circuit that directly applies the voltage of the alternating current power supply (AC) to the heater (Hl) via the normally open contact (Iv-1) of the relay (RA), and ) and the normally closed contact (RB-2) of a relay (RB) provided separately from the relay (1). ) is provided with a circuit for applying the voltage stepped down by the transformer (TR) to the heater (1-12).

When the main switch is turned on, the relay (
The normally open contact (RA, -1) closes, and at the same time the normally closed contact (RA-2) opens, the heater (Hl) is supplied with alternating current power (AC), and the pressure roller ( 4) or heated.

On the other hand, when the warm-up is completed, the relay (RA) is controlled to be turned off by the warm-up completion signal, and when the relay (1tA) is turned off, the normally open contact (RA-1) is turned off.
opens and the normally closed contact (RA-2) closes, so the heater (
An AC' voltage stepped down on the secondary side of the transformer ('nt) is applied to Hl).

With this control, the heater (1
12) A high AC voltage is applied to the heater (Hl), but during warm-up, the operation of the exposure lamp and the driving motor fly (not shown) is stopped. However, the total power consumption for one voice will not be exceeded. Moreover, since the power consumption of the heater (Ilz) can be set to a large value, the rise time of the surface temperature of the pressure roller (4) is shortened, and the temperature can be raised to a predetermined level during warm-up. On the other hand, during the standby period, the heater (Hl)
Reduce the pressure applied to the heater (Hz) and turn off the heater (Hz).
This power consumption is reduced when the surface temperature of the pressure roller (4) is a predetermined 111111°, that is,
It is set to maintain a temperature at which heat is not transferred from the surface of the heating roller (4) to the surface of the pressure roller (1).

In this example, the heating roller (1) is equipped with a 900W heater (
1-11) is built in, and the pressure roller (4) has a pressure of 350~■
It has a built-in heater (I-T2). The heating roller (1) is heated at 90°C during warm-up and copying operation.
Heated with 0W power consumption, surface temperature controlled to 200℃7
;! 41 has been done. The pressure roller (4) is heated with a power consumption of 350 W during warm-up, and after the warm-up is completed, it is heated with a power consumption of 100 W during the standby period.

The surface temperature of the pressure roller (4) during standby is controlled by the heater (I(2)
) and the heat h emitted from the surface of the pressure roller (4) are in equilibrium and the surface temperature of approximately 1.50°C is maintained. There is no need to provide control means. The heating roller (1) used in this example has a length of 320 mm and a Teflon inner (3) thickness of 4 mm.
0mm.

Inner thickness of core bar (2) 4. mm, outer diameter 5011rn, pressure roller (1) length 320mm, silicone rubber layer (6) I”?-5mm.

The inner thickness of the core metal (5) was set to 4 wn, and the outer diameter was set to 5 Q + nm. However, these set values, the set value of the heating roller (1) surface temperature, the heater (Y) and the heater (I-I2)
The power consumption must be set according to the configuration of the heat roller fixing device.

In addition, in the first embodiment, during warm-up, the rotating layer of the heating roller (1)! Fit is stopped, but in order to equalize the surface temperature of the heating roller (1) and the pressure roller (4), after warm-up is completed, the drive motor lock is activated and the timer circuit (12) is activated. The drive motor may be controlled to stop after a predetermined period of time has been counted by the timer circuit (12).

Alternatively, after the power is turned on and the surface temperature of the heating roller (1) reaches a predetermined temperature lower than the set temperature, the heating roller (1) may be rotated 151 revolutions until warm-up is completed. Furthermore, during the copying operation, while the exposure lamp is on, the heater (tlz) of the pressure roller (4) may be turned off. In this case, while the exposure lamp is on, the relay (RI3) may be turned on to open its normally closed contact (RB-2) and cut off the power supply to the heater (+12). In this way, power can be saved by turning off the heater (Hz) while the D'N light lamp is on.

Furthermore, the heater (Ii2) of the pressure roller (4)! The range force can also be controlled by phase control as shown in the 31st line.

By using such a control circuit, the timing of trigger pulse generation can be controlled by the phase control circuit (22) so that the AC voltage applied to the heater (Hz) is increased during warm-up and decreased during copying operation. For example, the timing of turning on the triac (TRC) is controlled,
The power consumption of the heater (Hz) is controlled. Note that the normally closed contact (RB-2) of the relay (i(B)) functions in the same manner as in the above embodiment.

Next, regarding the temperature characteristics and fixing properties of the heating roller (1) and the pressure roller (4), we will discuss the results of experiments conducted using a heating roller fixing device to which the present invention is applied, and the results of experiments conducted using a heating roller fixing device that does not have a heating means as in the past. A comparative study will be made with reference to the results of experiments conducted using a heat roller fixing device having a pressure roller (4). The diameters of the heating roller (1) and pressure roller (4), the thickness of the silicone rubber layer of both rollers, and the power consumption of the heater (Hl) built into the heating roller (1) are set as described above. It is the same as the example.

■ Regarding the surface temperature characteristics of the heating roller (1) and pressure roller (4) when 100 sheets of A3 size are continuously copied first thing in the morning (see BL), Fig. 4FA), tb+ In the figure, [Al, [
B) shows the surface temperature of the heating roller (1) and pressure roller (4), respectively. As shown in the figure, when comparing the surface temperature (A) of the heating roller (1) in the continuous copy area (C),
In the conventional case, the heat on the surface of the heating roller (1) is transferred to the pressure roller (
4) The heating roller (1) surface temperature (Al is large + j J
(the surface temperature tA+ decreases by about 40° C.), the heat on the surface of the heating roller (1) is not effectively used to melt the toner on the copy paper, resulting in poor fixing. On the other hand, in the case of the present invention, the pressure roller (4) is heated by a heater (Hz) with medium-high power, and its surface temperature (tB) is raised to about 100°C. (1) From the surface to the pressure roller (4) From the surface temperature to rF+, '
, the amount of heat generated is small, and the decrease in the heating roller (1) surface temperature FA,l in the continuous copying area (C1) is about 10°C,
Compared to the conventional method, the decrease in the surface temperature (Al) of the heating roller (1) can be greatly reduced. Therefore, the amount of heat effectively used to melt the toner on the copy paper is increased by 3 times compared to the conventional method, and the fixing The temporal change in the power supplied to the heater (Ht) is shown in Figure 4 (
As shown in C).

■ Regarding the temperature characteristics of the heating roller (1) and pressure roller (4) when 250 sheets of A4 paper are continuously copied after 30 minutes of normal copying operation after power-on. Figure 5 (see al, tbl) Figure 5 Fa), (b)
(A+) and (I3) indicate the surface temperatures of the heating roller (1) and pressure roller (4), respectively. .

As shown in the figure, when comparing the surface temperatures of the heating roller (1) and the pressure roller (4) in the continuous copying area (C1), it is found that in the conventional case, the heat on the surface of the heating roller (1) increases during the initial stage of continuous copying. The heating roller (1
) The surface temperature +A+ also decreases. Actually about 20℃
At the initial stage, the heat on the surface of the heating roller (1) is not effectively used to melt the toner on the copy paper.

On the other hand, in the case of the present invention, in the continuous copying area tel, the heating roller surface dlI +A+ and the pressure roller surface temperature (Bl are fixed with almost no fluctuation compared to the conventional one. This shows that the heat on the surface of the heating roller is not taken away by the surface of the pressure roller and is effectively used to melt the toner on the copy paper.

Therefore, the toner fixability to the copy paper is extremely good.

Figure 6 shows the temperature characteristics when high power is applied to the lower heater during warm-up, the heating roller (1) is rotated for 1 minute after it reaches a predetermined temperature, and then continuous copying is performed. .

Effects As is clear from the above description, the present invention provides a heating roller having a built-in heating means, a pressure roller which is in pressure contact with the heating roller and having a built-in heating means, a means for driving rotation of both rollers, and a heating roller having a built-in heating means. A system that controls the surface 15-,' of the heating roller at a certain time and outputs a signal when the surface of the heating roller reaches a predetermined temperature after the main switch is turned on. In the heat roller fixing device equipped with 1ll1 means, a controller is provided to switch the power supplied to the heating means of the pressure roller from the recitation power to the low power by the above (No. 6). The surface of the pressure roller can be heated by effectively utilizing power consumption, and during continuous copying, the amount of heat transferred from the surface of the heating roller to the surface of the pressure roller can be extremely reduced.Therefore, the heat on the surface of the heating roller can be used to heat the fixing toner. Since it is effectively used for melting, the fixing properties are extremely good.

[Brief explanation of the drawing]

FIG. 11 is a diagram showing the configuration of a heat roller fixing device to which the present invention is applied, FIG. 2 is a circuit diagram of an embodiment of the present invention, FIG. 3 is a circuit diagram of another embodiment of the present invention, and FIG. ai, (bl are T1 which shows the relationship between the surface temperature of the heating roller and pressure roller first thing in the morning and time in the present invention and the conventional heat roller fixing device, respectively.
, 4(C) is a diagram showing the relationship between the power supplied to the pressure roller and time, and 5th figure 1(a) and tb) are diagrams showing the relationship between the power supplied to the pressure roller and the conventional heat roller fixing device after power is turned on. Figure 6 shows the relationship between the surface temperature of the heating roller and pressure roller and time when continuous copying is performed after 30 minutes of copying operation. FIG. 3 is a diagram showing the temperature characteristics of a heating roller and a pressure roller when rotated for one minute. (1)... Heating roller (4)... Pressure roller (10)... Temperature control circuit (11)... Drive control circuit (12)... Timer circuit (Hl),
(H2)...Heater recess...Drive motor ('
l)...1-Lance (TRC)...Triac (
■Temperature sensing element applicant Minolta Camera Co., Ltd. Figure 1 Figure 2 nrIrJC#) Figure 4-@(α) Figure 4(C) Figure 4(b) GinP allowed (7 pieces)

Claims (1)

[Claims] 1. A heating roller having a built-in heating means, a pressure roller that is pressed against the heating roller and having a built-in heating means, a rotation driving means for both rollers, and controlling the surface temperature of the heating roller. and a control means for outputting a signal when the surface of the heating roller reaches a predetermined temperature after the main switch is turned on, the heating roller fixing device is configured such that the electric power supplied to the heating means of the pressure roller is controlled to a high power level by the signal. A heat roller fixing device characterized in that it is equipped with a control means for switching from dry to low tonne force. 2. The heat roller fixing device according to claim 1, wherein the heating roller is rotated for a predetermined period of time by the rotation driving means after the heat roller reaches a predetermined temperature.