JPS5962883A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate defects of fixing without rotating always a heat roll and a pressure roll or using an internal heating-type pressure roll by providing a mechanism which rotates the heat roll and the pressure roll in cooperation with each other after the time, when the surface temperature of the heat roll reaches a prescribed value, or the elapse of a prescribed time from power-on at the start time. CONSTITUTION:When a potential V6 corresponding to the surface temperature of a heat roll 1 is equal to or higher than a reference potential VR corresponding to a prescribed temperature after a main switch S1 is turned on, the heat roll 1 and a pressure roll 7 are rotated cooperatively only for a time DELTAt by its change signal, and heat is used efficiently to raise the surface temperature of the pressure roll 7. Further, the surface temperature of the heat roll 1 is not lowered extremely to achieve a good fixable state in a short time. Consequently, defects of fixation are not generated at all when a toner image T is fixed to a supporting material P.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus having a heat fixing device for fixing a toner image onto a support material. Recently, pressure rolls without heating means have come to be used in order to simplify the structure and reduce costs.

However, in this type of fixing device, while both rolls are stopped, only the surface of the heating roll rises even when the power is turned on, and the pressure roll t is almost at room temperature. When the warm-up is completed and copying is started, the fixing temperature drops to 11] because the heat roll temperature is absorbed not only from the paper but also from the pressure roll with a large permissible Jrl at the beginning of the copying cycle. This is a cause of poor fixing. This phenomenon is particularly noticeable in the first copy in the morning.

In order to eliminate such drawbacks, the heating roll and pressure roll are constantly cooperating. + Rotate Py! A machine that uses an internally pressurized pressure roll (or
Mechanisms that combine these have been proposed, but these have the following drawbacks.

(11) The qO warm-up time is longer in machine A, which is constantly rotating (heating roll and pressure roll).

0 The life of the roll is short and constantly produces noise.

(2) Mechanism 0 that uses internally heated pressure rolls Warm amp time is long.

0 The cost will be high.

0 Out of the power consumption of the copying machine, the power consumption allowed for the fuser is divided into the heat source for the fixing roll and the heat source for the pressure roll, and this method of division does not impair fixing performance, and In order to avoid prolonging the start-up time and to avoid causing the rubber to sag, the electric power of the upper and lower heaters must be selected taking into account the power supply. This will exceed the power consumption and become uneconomical.

0 There is a risk of peeling of the rubber contact 717 layer.

0 It becomes necessary to provide temperature control, and the configuration is complicated,
Costs will rise.

O The surface temperature of the pressure roll rises slowly and has no effect on sticking properties first thing in the morning.

(3) Combination of both of the above 0 It is effective, but it has the drawbacks of both.

SUMMARY OF THE INVENTION The present invention aims to provide an image forming apparatus having a fixing device that eliminates the above-mentioned drawbacks of conventional fixing devices, can perform good fixing, and can simplify the configuration. This is the purpose.

An embodiment of the present invention will be described below.

The fixing device shown in FIG.
It consists of a pressure roll without any heating means. The heating roll 1 has a roll core 2 coated with i! such as Teflon (trade name) or silicone rubber on the surface. It has a structure in which the LIC-type material layer 3 is torn thinly, and a heating means 4 such as a heater pump is built inside. Reference numeral 5 denotes a controller for controlling the temperature of the heating means 4, which detects the surface temperature of the heating roll 1 with a temperature sensor 6 such as a server star installed close to or in contact with the surface of the heating roll I. The surface temperature is always maintained at a constant temperature by controlling and operating the voltage mechanism 5a on the heating means 4 based on the surface temperature. The pressure roll 7 has a structure in which the surface of a roll core 80 is coated with a moldable material layer 9 made of noricorn rubber or the like, and is in pressure contact with the heating roll 1.

The rotating shaft 1' of the heating roll 1 and the pressure roll 7
The rotating shaft 7' is rotatably supported by well-known support means 12. Further, these rolls 1 and 7 are rotationally driven by the e'M M force from a motor 11 etc. transmitted by a well-known four-motion coupling means. Driving force is applied to the gear 1a to rotate the heating roll 1, while the pressure roll 7 rotates as a result of the heating roll I. During fixing of the thermal toner image T on the support material P, well-known control is performed. By roll 1,
7 is rotated. Furthermore, motor 11 has 1 drive 1ff.
1J control means 10 is connected, and this drive control means 10 receives the output from the temperature detector 6 and the switching output of the main switch 81, or controls the motor 11 by means 10a and control circuit 10b contained therein. Rotation ＾￥g! It is the one that controls the VI. In this mechanism, the main switch (power w,) is turned off during warm-up.
Immediately after applying the force n, the heat roll 1 and the pressure roll 7 are stopped, but after a predetermined time when the surface temperature of the heat roll reaches a predetermined temperature, the timer means 10a operates and (1 (old,
7, it would be good to have something that decides everything when it is activated. ) motor] 1 for 5 hours, heat lff-le 1 door J
ll Rotate the EJE roll 7 in f, t, directions 0 2nd
1"Al'r, this heating roll] and force t) Pressure roll 7
% at 9 o'clock at the beginning like this? 1'j i'j4 After the heating roll surface temperature reaches a predetermined temperature after charging/heating, a rotary heating machine fl' for a predetermined period of time is shown. In the figure, CI and C2 are capacitors, and R1, R2, IL3, R4 and i4i are air resistances, and have capacitance and negative values and resistance values of γ1. DC is the alternating current, 13 is the output from the temperature sensor 6.
21 is a resistor R, which compares
i, tt2. It is an input means to the thyristor 14 that shapes the waveform of the output from the capacitor C1 and the comparator 13. A thyristor 14 is normally in an off state, but becomes an on state when the capacitor -CI is charged in response to the high (fj) signal of the comparator 13 and reaches the gate potential.

There is a reed near this thyristor 14, and a connection point 14a between the resistor R3 and the monostable multivibrator 15 has an AC potential D.
The voltage at the connection point 14 becomes High due to the potential of
a becomes LOW and sends a signal to the monostable multipipe rake 15 to activate the monostable multivibrator. Therefore, the monostable multivibrator 15 operates for an operating time Δt determined by the resistor R4 and the capacitor C.
By driving the motor 11 only for a period of time Δt, the heating roll 1 and the pressure roll 7 are caused to rotate together. This time Δt is variable depending on the values of the resistor R4° and the capacitor C2, but this activation signal may be sent to the rotation of the roll pair during fixing or the like.

That is, after turning on the main switch S1, the heating roll 1 is turned on.
When the potential ■6 corresponding to the surface temperature of the Since the surface temperature of the pressure roll 7 can be increased and the surface temperature of the heating roll 1 is not lowered to the opposite end, a good fixing state can be achieved. Therefore, when fixing the toner image T on the support material P, no fixing failure occurs.The circuit shown in FIG.
The motor II is operated only once during the wait time when the potential v6 reaches the reference potential VR. After that, the pressure roll 7 is heated to a temperature necessary for fixing by the heat radiation of the heating roll 1, so there is no need to rotate both rolls together again. However, if this device is used in a cold region, good fusing can be achieved when the soil is being erected, but if the copy is not made over a long distance, the surface temperature of the pressure roll 7 will be extremely high depending on the environmental temperature. may decrease. FIG. 3 is a circuit diagram of a more preferred embodiment of the present invention that enables good fixing even in such rare cases. A circuit including a regulator 18, a monostable multivibrator 16, and a transistor 17 is incorporated between the thyristor 14 in the circuit diagram and the part where it is grounded. This integrated circuit will be mainly explained below. As mentioned above, during the wait time, the potential v6 is equal to the reference potential V
When the temperature exceeds R, the transistor is in an on state, so the heating roll 1 and the pressure roll 7 rotate together and are maintained in a good state.

By the way, in this embodiment, the motor 11 is connected to the pressure roll 7 and the heating roll 1 is configured to rotate following the pressure roll 7, and a temperature sensor 6a is provided on the surface of the pressure roll 7. ing. A comparator 18 compares the output potential V, a of the temperature sensor 6a with a reference potential Vna at which fixing failure starts to occur. This output 7J potential Vs
When a becomes smaller than the reference potential Via, the comparator 18 outputs a High signal due to the change, and the monostable multipipe lake 16 receives this signal and is activated by a signal that is activated only for the time set by the resistor R5 and the capacitor C8 (this (It is preferable that the set time is short because it outputs a signal to turn off the transistor.)
ff. At the same time, the thyristor 14 is turned off and the connection point 14a changes from the Low state (the state during the wait time described above) to the High state. At almost the same time, a high signal (v,〉■R) from the comparator 13 is output.
Therefore, the connection point 14a becomes Low and the monostable multivibrator 15 is activated. Therefore, the motor 11 is driven for the time Δ, causing the heating roll and the pressure roll to rotate together.

As a result, the surface temperature of the pressure roll is always maintained at an effective temperature for fixing toner images, so excellent fixing without defective fixing is possible even in rare cases that occur after a long period of time or when used in cold regions. becomes.

In the circuit shown in Fig. 2.3, a circuit having monostable multivibrators 15 and 16 is used, but the heating roll 1 and the pressure roll are Any circuit that rotates the heating roll 1 and the pressure roll 7 together (=!i11) in response to changes in the surface temperature of the roll 7 or under temporal control can be applied to the present invention.

Next, the effects of the present invention will be explained with reference to Fig. 4.5.6. Fig. 4 is similar to Fig. 1, and is similar to Fig. 1, and is similar to Fig. The relationship between the surface temperature of the heating roll and pressure roll and time is shown. In the figure, A shows the temperature change of the heating roll 1, and B shows the temperature change of the pressure roll 7.

As shown in this figure, during warm-up (power on)
Since the heating roll 1 and the pressure roll 7 are stopped, the surface temperature A of the heating roll 1 increases with time, but the surface temperature B of the pressure roll 7 increases in areas other than the contact area with the heating roll 1. The temperature is kept at room temperature Ta. When the warm-up is completed and copying begins, the heating roll 1 and the pressure roll 7 rotate, but in the early stages of copying, the heat of the heating roll 1 is effectively used to melt the toner on the transfer paper. Instead, it is consumed to increase the temperature of the pressure roll 7. That is, although the surface temperature B of the pressure roll increases, the surface temperature AFJ of the heating roll decreases, which may result in poor fixing. This phenomenon occurs especially at low temperatures (5°C
).

The present invention can eliminate such fixing defects, and in particular, it is possible to eliminate such fixing defects by using a system in which a heating roll and a pressure roll are constantly rotated, or an internally heated pressure roll, as previously proposed. This is an attempt to eliminate fixing defects without necessarily having to do so. To this end, in this embodiment, the heating roll and the pressure roll are rotated in cooperation with each other after the surface temperature of the heating roll reaches a predetermined temperature or after a predetermined time has elapsed after one kongyuan is added at the time of startup. ! I is provided.

FIG. 5 shows a typical relationship between the surface temperature of the heating roll and pressure roll and time in the apparatus of the present invention. In a device having a simple timer means 10a as shown in FIG.
During warm-up, the surface temperature A of the heating roll 10 increases with time during a period of time after the power is turned on (cooperative rotation start time), but the surface temperature B of the pressure roll 7 is maintained at room temperature Ta. At time 11K)1, the timer means ioa operates to rotate the motor 11, causing the heating roll 1 and the pressure roll 7 to rotate together for a rotation time t. Due to this rotation, the surface temperature of the pressure roll 7 increases,
In addition, the surface temperature of the heating roll 10 does not show an extreme rise in temperature, and the slope of the rise is only gentler than before rotation, and the standby setting temperature T of the 7JII heating roll 1 is reached.
It continues to rise. The above-mentioned operating time t1 and rotation time t! What about warm-up time, roll configuration, power consumption, heating rolls? Ni\YongF'! It can be selected as appropriate depending on the material, etc. This rotation time t may be set to a time period after the operation time t1 has elapsed until the warm-up is performed. Also, in this example, time 1
．． ．． 1. Although the timer means 10a is used for this purpose, instead of this time, a function may be provided to start or stop the rotation depending on the number of revolutions of the motor or the surface temperature of the heating roll/pressure roll.

In the non-example, after the electric current is applied to the holes ε and r, the surface of the heating roll ? During operation l'1i1t, when 1irh degree reaches the predetermined temperature, p1 of the roll after (> o)
Starting the rotation is 24j: 7i4;14'i 叡. If the operating time is 11 times, that is, if the initial / ノ) is also rotated, then the addition from the initial stage is ff:l l-7
- L7 Tenori,'! X% is carried out and heating [1
-Release from rule 1 ij% i? ] i product is state big VC
As shown in Figure 6, the rising gradient of the surface temperature of the heating roll 1 becomes gentle, so that 11j becomes very stiff at the time of start-up, and 1(i energy and Furthermore, due to the heat insulation properties of the jJ5 rubber layer that provides sudden V heat to the pressure roll 7 as in the present invention, the
Since the heat of 711 is transmitted to the inside of the rubber layer, the surface temperature of the processing roll rises quickly as shown in No. 5121. When rotating the heating roll 1, the rise of the heating roll 1 becomes gradual, and the rubber of the pressure roll 7! (inside)
, 'lj K- Since the rotation is long enough for a certain amount of surface heat to be transferred, the pressure low shift 0 surface temperature also starts to rise slowly. Therefore, according to the above, it is possible to accelerate the rise of the pressure roll surface temperature without impairing the rise time of the heating roll 1.

When copying is performed after the heating roll 1 has reached the standby set temperature r, Ka, the temperature of the heating roll 7 has fewer rises than that shown in FIG. 8112, so that the fixing is better.

Operation 11 (b) It goes without saying that the time tl and the rotation time 1° should also be determined by the saturation temperature or higher temperature of the pressure roll 7 after this standby release frt. Setting the roll 7 to a predetermined temperature also has the effect of greatly contributing to energy saving.

The above-mentioned operating time t, rotation time 'bi''j, primary set temperature 1' in heating roll 1, and secondary set temperature T
, may be determined by . It is desirable that T be set at 70 times or more of the standby set temperature T.

Such an embodiment of the present invention is shown in No. 7N. In Figure 7,
19.20 is a comparator, 21 is a J.((dynamic fl+')) elevation circuit, and 11 is a roll PI<motive source, that is, a motor.

In this device, C, roll L's Umensho 1 (Intan y9
It is detected by the thermistor 6 and input to the comparator 19.20, respectively.
The signal b1 to the group f corresponding to the surface temperature Ill of the heating roll 1 and the surface temperature T1 of the heating roll), I-I! Compare with the number C it, a≧l) (The surface temperature of the heating roll 1 is the primary setting it, r, [T, or more)
In this case, a signal b' is issued to the roll drive control circuit 2I. When the signal b' is sent to the roll drive control circuit 21, the roll 6 is moved by the roll drive source (motor) 11. Then, when the danger signal a is a≧C (the surface temperature of the heating roll 10 is higher than the second set temperature T!), the roll drive (b control) is performed.
A signal C' is issued to the circuit 2I, which causes the roll drive source (motor) 11 to stop. Therefore, the same effects as described above can be obtained. Mechanical tA formation・111
．． A control means that combines a gas configuration may also be used.

As described in detail above, the present invention promotes the rise in the surface temperature of the pressure roll by rotating the heating roll and pressure roll together after a predetermined time has elapsed after the power is turned on during warm-up. , the surface temperature of the pressure roll is raised above room temperature, good fixing can be obtained from the beginning when the machine is started, and an inexpensive fixing device can be provided without increasing power consumption. . Furthermore, it goes without saying that the above sequence may be made to work only at low temperatures. The above-mentioned cooperative rotation may be performed at regular intervals or as needed, and the operating time may be set to any desired time. Further, the heating roll and the pressure roll may be driven so that one rotation is driven by the other, or both rolls may be driven by independent drive sources.

In this way, the present invention can prevent the occurrence of fixing failures without the need to constantly rotate the heating roll and the pressure roll, and without using a pressure roll whose interior is heated.

In addition, although the above first explanation was explained regarding a heating roll and a pressure roll, the present invention is applicable not only to rolls but also to members such as belts.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the fixing device according to the present invention, FIG. 2 is an operation control circuit diagram of the embodiment of the fixing device according to the present invention, and FIG. Implementation of i,? lJ
Other actuators 1111 times iA3 Figure 4 Implementation 1 of the present invention
A diagram showing the 4th section similar to Figure 4 in Ruri, Kan 612
1 is the surface of the roll that separates 0ζ when the roll and pressure roll are rotated from the initial stage (in the following device).・1: Diagram showing raw and time ii yarn, FIG. 7 is a diagram showing another embodiment of the present invention 0 1: JJII Kusuro multi roll 8: roll core, 3, 9 Fli type attaching material i '+: Iη, 1 digit Kakamo Tesetsu, 5 digit system i
11 units, 6°) and 6a is /1. I HJX wisdom, 4 (, 7 is t) Il f
E Low %, 10 is drive 161J control means, 11 is motor.

Claims (4)

[Claims] (1) A heating member having a heating means and in contact with the toner image, a pressure member for fixing the toner image by sandwiching and conveying the toner image support material between the heating member, and these heating γS11 A rotation drive means for rotating the moon and a pressure member, and a heating means that starts operating at the time of startup, and after the surface temperature of the heating member reaches a predetermined temperature, the heating member and the pressure member work together. An image forming apparatus having a rotation control means. (2) The heating means includes a heating section I that contacts the toner iron, and a pressure section I that holds and conveys the toner image support material between the heating member and the pressurizing section A that controls the toner density. A rotation drive means for rotating the heating member and the pressure member; and a rotation drive means for operating the rotation drive means to cause the heating member and the pressure member to cooperate when the surface temperature of the heating member reaches a first temperature during startup. an image forming apparatus comprising: a control means for causing the rotation to rotate; and for stopping the rotation when a second temperature higher than the first temperature is reached. (3) A heating member having heating means and in contact with the toner image, a pressure member for fixing the toner image by sandwiching and conveying the toner image support material between the heating member, and these heating members. An image forming apparatus comprising: a rotation drive means for rotating a pressure member; and a control means for causing the heating member and the pressure member to rotate together after a predetermined period of time has elapsed since activation of the heating means at startup. (4) a heating member having heating means and in contact with the toner image; a pressure member for conveying the toner image support 4J with the toner image support 4J sandwiched between the heating member; A rotary drive means for rotating the heating member and the pressure member; after a first predetermined period of time has elapsed since the heating means is started to operate at the time of startup, the heating member and the pressure member start cooperative rotation; control means for stopping the rotation after a predetermined period of time;
An image forming apparatus comprising: