JPS5852669A - Heat fixing roller - Google Patents

Abstract

PURPOSE:To preheat a press-contacting roller sufficiently by measuring the time between the time when the surface temperature of a heat roller attains to the 2nd set temperature T2 and the time when it attains to set temperature T1, and rotating the rollers in proportion to the measured time. CONSTITUTION:When the surface temperature of a heat roller 1 attains to the 2nd set temperature T2, a count-up signal is inputted from an oscillating circuit 19 to the count-up input terminal of a counter 20, which counts up successively. Then when the surface temperature attains to set temperatue T1, a flip- flop 8 is set and an AND gate 9 is closed, so that the counter 20 stops counting. For this purpose, the time between the time when the surface temperature of the heat roller 1 attains to the 2nd set temperature T2 and the time when it attains to the set temperature T1 is measured by the counter 20 and the heat roller 1 and press-contacting roller 3 is rotated in proportion to the measured time to preheat the press-contacting roller 3 according to said time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing unit of an electrophotographic copying machine, and more particularly to a heat fixing roller that includes rollers that are in pressure contact with each other and that is provided with a heat source on the roller that comes into contact with a toner image on a copy sheet to be fixed. .

In general, a heat fixing roller is composed of two rollers, an upper and a lower roller.The -1 roller, which mainly contacts the toner image transferred to the copy paper, is a heat roller that has a heater inside, and the lower roller - 1-A pressure roller that is in pressure contact with a heat recording roller. Normally, when the temperature of these two rollers reaches a predetermined temperature at the temperature detection position of the ten rollers after the power is turned on, the Reso and E lamps will light to indicate that copying is possible, and printing will begin in this state. When you press the button,
It is energized when the drive motor rotates for the first time. The reason why the rotation of the drive motor is started as late as possible is to avoid operating the device as much as possible when unnecessary.

Here, the heat fixing roller is provided with a temperature detecting means, and after a predetermined temperature is detected by the detecting means, the temperature is controlled by a temperature control circuit.

It is controlled to maintain a predetermined temperature. Normally, the temperature of the roller described in - is controlled to the set temperature, but if the power supply voltage is lower than the specified voltage or the ambient temperature is lower than the normal temperature, it is difficult to control the temperature to the specified temperature for the following reasons. becomes.

As mentioned above, the heat fixing roller has a built-in heater only in the clay roller of -1112 rollers, and at this time, heat is transmitted from the heater to the 4-roller and mainly to the lower roller and the lower roller. is transmitted to the lower roller from the contact area with the lower roller. However, since neither roller rotates until the ready lamp is turned on, the -1-distribution contact portion is always the same. Therefore, even when the upper roller reaches a predetermined temperature, the temperature of the portions of the upper roller other than the -1- distribution contact portion remains close to the ambient temperature. In this state, when you press the print switch and start the copying process, -1-
The thermal fixing roller rotates. At this time, since the 1-roller, which has risen to a predetermined temperature, comes into contact with the lower roller whose temperature is approximately equal to the ambient temperature, a large amount of heat is removed from the 1-roller. Even so, under normal conditions and drying conditions, it is possible to maintain the temperature of the fourteenth roller at a predetermined temperature by increasing the input to the heater in the thousand-day roller using the temperature control circuit of the heat fixing roller. It is.

However, if the ambient temperature is low or the power supply voltage is lower than the specified voltage, even if the input to the heater is increased as much as possible, it will not be possible to supply the same amount of heat as the heat taken away. -1-Lola's l! In some cases, it is unavoidable that the temperature becomes even lower than the fixable limit temperature, which is lower than the predetermined temperature.
there were. Therefore, even if the copy paper holding the transferred toner image on its surface passes through this heat fixing roller 17,
・Fixing of the Na image (4) became incomplete.

The present invention has been made in view of the above drawbacks, and even when the ambient temperature is low or the power supply voltage is low,
Before the ready lamp lights up, that is, before the copying state is activated.
This method is characterized in that the lower (pressing) roller is warmed in advance by rotating the heat-recording and fixing roller.

Further, the present invention has a major feature in that the heat fixing roller (1) and (2) is rotated. In other words, a second set temperature 1゛2, which is slightly lower than the set temperature T1 of the heat roller, is determined, and from the time when the heat roller reaches the set temperature T2 to the time when the heat roller reaches the set temperature TI. The time t is measured, and the heat recording roller and pressure roller are rotated in proportion to this time, and the pressure roller is preheated for a time proportional to the recorded time.

As a result, for example, the preheating time of the pressure roller changes in inverse proportion to the ambient temperature, and the preheating time is longer at low temperatures than at high temperatures, allowing manual preheating to be performed and preventing fixing failures etc. at low temperatures. .

Hereinafter, the heat fixing roller of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a side sectional view showing a heat fixing roller according to the present invention. In the figure, an upper roller 1 is a heat roller equipped with a heater 2 inside, a lower roller 3 is a pressure roller that is pressed against the heat roller 1 with an appropriate pressure, and these rollers 1,
3 constitutes a heat fixing roller. As the rollers 1 and 3 are rotated in the direction of the arrow, the fed copy paper 4 is sandwiched between the rollers 1 and 3, and a toner image 5 is formed on two sides.
The image is fixed by the heat of the heat roller 1. The above roller 1゜3
is driven by rotation of a main morph (not shown).

FIG. 2 is a circuit diagram for driving the heater 2 of the heat recording roller 1, and shows the set temperature TI of the surface of the heat roller 1.
+ Controls the drive of the rollers 1 and 3 of the present invention with respect to T2. 61 in the figure is a temperature sensing element that is attached to the surface of the heat roller l shown in FIG. →No-mister 6 is connected in series with resistor R3, and voltage (V) is supplied between it and the ground.

Resistors R, , R2, and R3 are connected in parallel to this series connection circuit of the → no mister 6 (resistance R5) and the resistor R4. Further, reference numeral 7 is a comparator for keeping the heat roller l at a set temperature of 1.1, and the set temperature T is set at the negative end Tm.
Resistance R is the reference value of I (180°C).

The combined resistance of R2 and R3 is connected to the 4- side terminal of Ichikawa 7, which is divided by A, and the resistance of the thermistor 6 is <5 and resistor 180.
When the temperature exceeds (or is equal to) .degree. C., the output of the comparator 7 is inverted to fl-II. In other words, if the crystallinity is less than the set crystallinity T1, the IIJl force of the comparator 7 is "'II".

The output of the comparator 7 is supplied to the cent input terminal f of a flip-flop 8, and the flip-flop 8 is set when the output of the comparator 7 is ++Ll+. A reset input terminal of the flip-flop 8 is supplied with an IR signal that is an initial reset signal that is output when the copying machine is powered on.

The reset output Q of this flip-flop 8 is supplied to one input terminal of a three-way AND gate 9. Further, the set output Q of the flip-flop 8 is supplied to one input terminal of a two-man AND gate 10. -1-
The output of the ant gate 10 switches the transistor I2 via the OR gate II. This transistor 12 is a switching element for supplying voltage +-V to a main motor relay 13 for rotating the main motor M. Immediately, when the base of the l transistor 12 becomes 'TI', the relay 13 is energized and its contact is turned on, causing the main motor M to rotate.

A motor drive signal from the copying process control circuit 14 is supplied to the other input terminal r- of the OR game 1-11.

The copying process control circuit I4 performs conventionally well-known copying control in response to the operation input of the print switch 15.
When driving the main motor M, a drive signal (II'') is output to the OR gate 11 described in -1-.This copying process control circuit I4 executes copying control in accordance with the operation of the print switch 15; When the copying is possible (ready) state, that is, when the heat roller 1 has not reached the set temperature T1 (j), copying control is not executed.

Also, the output of the comparator 7 (supplied to the base of the J transistor I6 and drives the heater control circuit 17. The output of the comparator 7 is "Il", that is, the set temperature T
When the temperature is below I (180° C.), the heater control circuit 17 is supplied with voltage +■, and controls the power supply to the heater 2 of the heat roller 1. As a result, the temperature of the heat roller 2 is raised, and when the set temperature is reached, power supply to the heater 2 is stopped.

On the other hand, reference numeral I8 is a comparator that detects the second set temperature T2, and its output is inverted from "■7" to II H11 when the temperature is higher than the set temperature T2. ” 2 The set temperature in description 2 is T2, which is slightly lower than the set temperature of 180°C, for example.
Set to 60°C. Therefore, the 4-
(The i11 terminal is set to be the reference temperature of the set temperature T2. The output of this comparator 18 is
9 is supplied to one input terminal. Antogame 1・
Another input terminal of 9 is supplied with a voltage from an oscillation circuit 19. In other words, if both the output Q of the flip-flop 8 and the output of the comparator I8 are "II", the AND gate 9 transfers the oscillation signal (count-up signal) of the oscillation circuit 19 to the next up-down counter (hereinafter referred to as "count-up signal"). -F
20 (referred to as a counter) is manually input to the up input terminal r. The counter 20 is manually input to the top of the up input (I'3-
When input is input manually to the down input terminal, the contents of the counted up count are sequentially counted down, and when J runt down cannot be performed, This output B is supplied via the inverter 21 to the other input terminal r- of the two-way game 1.
10 is closed, the main motor relay 13 is driven, and the motor M is stopped.

The output of borrow B is also supplied to the base of transistor 22 to switch the transistor 22. The collector of the transistor 22 is the output T of the signals gW, T, L, for indicating the standby state of the copying machine. Therefore,
If the transistor 22 is OFF, the waiting signals w, T, r
-, becomes "'H", and this is transferred to the copying process control circuit 1.
By inputting 4, the operation of the print switch 15 is invalidated. This signal W.

T and L are used as signals to indicate the copy-ready state, and +11-++ turns on a lamp or the like to indicate the copy-ready state depending on the surface temperature of the heat roller (for example, set temperature 'r1). let

The counter 20 is reset by the initial reset signal "9JR" when the power is turned on, and the down input terminal receives a signal indicating the number of rotations of the heat roller or pressure roller 3. A light-emitting element 24 and a light-receiving element 24 are provided between the slit disc 23 directly connected to the rotating shaft of the roller 3, and the light-receiving element 2 receives light through the slit.This slit signal is converted into a countdown. The down input terminal of the counter 20 is manually inputted.

The slit disk may form one slit, and the slit signal corresponding to one rotation of the roller 1 or 3 may be input, or a large number of slits may be formed. Alternatively, the countdown signal may be generated not by the rotation of the rollers 1 or 3 but by the rotation of a photoreceptor that rotates simultaneously with the rollers 1 and 3.

In the above circuit configuration, the 21-power supply of the copying machine is turned off.
If N, initial reset signal 9 TR (
"H") is output, and the flip-flop 8 is reset. At the same time, the non-counter 20 is also reset. By being reset, the flip-flop 8 supplies this reset i/output Q to one input terminal of the anti-games 1 and 9. With this power ON, the output of the comparator 7 becomes "IT"'2, power is supplied to the heater 2 of the heat roller 1 by the comparator I/-7 and the beater control circuit 17, and the heat roller 1 is set. A one-degree control is performed to maintain the temperature at T1.

Then, when the surface 71' of the heat recording roller 1 reaches the second set temperature T2 by 1.1 degrees, the comparator 18 changes to "1".
Inverted from -11 to 1 "H". Here, since the flip-flop 8 is reset when the power is turned on, the AND gate 9 is enabled, and the count-up signal from the oscillation circuit 19 is inputted to the count-up input terminal of the counter 20, and the counter 20 is sequentially Do a count. Note that when the counter 20 is powered on, the output of its borrow B is "+I-++", and the standby signals W, T, L,
is being output.

Subsequently, ``-surface temperature of the heat recording roller or set temperature T,
Once the output is reached, the output of comparator 7 changes from “H” to “1”.
At the same time as the rotation is reversed to 7° and power supply to the heater 2 is stopped, the flip-flop 8 is set. When the flip-flop 8 is set, the ant game 19 closes,
The counter 20 stops counting, the AND gate 10 opens, the main motor relay 13 is energized, and the main motor M rotates. As a result, the heat roller and the pressure roller 3 rotate. In synchronization with this, slit disk 2
A slit signal (countdown signal) from rollers 1 and 3 is supplied to the counter 20, and the counter 20
Countdown is performed in proportion to the rotation of. Due to this rotation, the heat of the heat roller 1 is transmitted to the pressure roller 3, and the pressure roller 3 is uniformly heated as a whole. If the surface temperature of the heat roller 1 accordingly falls below the set temperature T1, the output of the comparator 7 becomes "H", and temperature control is performed to maintain the surface temperature of the heat roller 1 at the set temperature T1.

At this time, the output of the comparator 7 becomes II i (++, so the flip-flop 8 is reset.11
Therefore, the count-up signal from the oscillation circuit 19 is not input to the counter 20.

-1- The counter 20 inputs a countdown signal generated by the rotation of the heat roller 1, etc., and when the countdown becomes impossible, the output of the borrow B becomes "H". Accordingly, the AND gate 10 closes, the main motor stops rotating, and the heat roller 1 and the pressure roller 3 stop rotating. While the pressure roller 3C is rotating, heat is transferred and sufficient preheating is performed. Also, the output of borrow B is “H”
''' indicates the copying machine's standby status. Signals W, T,
When the temperature of the heat roller I reaches, for example, the set temperature, a signal indicating the CJ, copying=T capability state is output, and the copying process control circuit 14 becomes capable of copying control.

- Soil, as mentioned above, the surface of the heat roller 1 is at the second set temperature T2
This means that the counter 20 measures the time from when the temperature reaches the set temperature T1. Then, the heat roller 1 and the pressure roller 3 are rotated in proportion to this measured time, and the pressure roller 3 is preheated in accordance with the above-mentioned time. The time measured by the counter 20 corresponds to the ambient temperature, power supply voltage, etc. Under conditions of low ambient temperature, it takes a long time to reach the set temperature T, and the -h counter 0 measures the corresponding time, so by increasing the preheating time of the pressure roller 3, I can do it enough. In other words, under conditions such as when the ambient temperature is low or the power supply voltage is low, it becomes impossible to supply thermal slip to the heat roller 1 corresponding to the heat removed by the pressure roller 3, resulting in poor fixing. . However, by preheating the pressure roller 3 for a period of time according to the conditions specified in -1-, the heat wave applied to the pressure roller 3 can be reduced and the above-mentioned fixing failure can be prevented.

Here, the rotation of the heat roller 1 etc. is proportional to the time measurement by the counter 20, but by changing the proportionality constant at this time, the rotation speed (time) etc. of the heat roller 1 etc. can also be varied. ”
- To change the proportionality constant, either change the oscillation frequency of the oscillation circuit 19 or change the number of slits in the slit disk 23, and both can be selected appropriately. In order to maintain the heat roller 1 at the fixing temperature d1 without causing the heat roller 1, it is sufficient to set the pressure roller 3 to a preheating limit.

Further, although the counter 20 is provided in this embodiment for time measurement, the present invention is not limited to this, and the time d1 measurement may be performed by providing the 1I4 #1 circuit itself, but the present invention is not limited to this. .

As described below-1-, according to the heat fixing roller J of the present invention, the time from the time when the surface temperature of the heat roller reaches the second set temperature 'r2 to the time when it reaches the set temperature 'i' is measured. Since both rollers are rotated in proportion to this fixed time, under normal power supply voltage conditions or ambient temperature conditions of 41 degrees, the rotation time or number of rotations of the heat fixing cola can be adjusted. On the other hand, under adverse conditions where the rising time becomes longer, the temperature of the pressure roller is slow to rise and the temperature of the heat roller is slow to recover, so the rotation time or number of rotations of the heat fixing roller may be increased. It can be said that it is a rational and excellent device that can sufficiently preheat the pressure roller.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a heat fixing roller according to the present invention;
FIG. 2 is a circuit configuration diagram showing a specific example for implementing the present invention. 1: Heat roller, 2: Heater, 3: Pressure roller, 4:
Copy paper, 5: Toner image, 6: Thermistor, 7: Comparator for setting temperature 'FI detection, 8: Flip-flop, 1
3: Main motor relay, +4: i-printing process control circuit, 1
7: Heater control circuit, 18: Temperature T2 detection comparator, 20 near tube down counter, 23 Nislit disk. Agent Patent Attorney Aihiko Fuku

Claims (1)

[Claims] 1. A heat fixing roller comprising a heat roller equipped with an internal heat source and a pressure roller that is pressed against the heat roller,
``-a sensing element that detects the surface temperature of the heat-recording roller; and a temperature control circuit that maintains the heat-recording roller at a set temperature based on the sensing element;
a detection means for detecting the set temperature of the second set temperature, a time measuring means for measuring the time from the time when the second set temperature is detected by the detecting means until the set temperature is reached, and a time measuring means that is proportional to the measurement time of the time measuring means. - a rotational drive means for rotating both the recording rollers; 2. The heat fixing roller according to claim 1, wherein the roller rotation driving means rotates both rollers in response to a signal indicating that a set temperature has been reached.