JPS5868770A - Heat fixing roll - Google Patents

Abstract

PURPOSE:To prevent the reduction in the temp. of rolls below the fixable temp., by rotating a roll for heat fixing and keeping a lower (press contact) roll prewarmed prior to lighting of a ready lamp when an ambient temp. or a source voltage is low. CONSTITUTION:When a main power source of the body of a copying machine is turned on, electric power is supplied to the heater 2 of a heat roll 1 by a heater control circuit and the temp. of the roll 1 is controlled so as to be kept at a set temp. T1. Upon turning on of the power source, the roll 1 is heated by the heater 2 and at the point of the time when the temp. thereof exceeds a temp. T2, a main motor is driven to rotate the roll 1 and a press contact roll 3. When the rolls revolve, the roll 1 is heated gradually, and the roll 3 is heated gradually as well at the temp. lower than that of the roll 1. When the surface temp. of the roll 1 arrives at the temp. T1, the ready lamp is lighted and the machine is ready to start copying.

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 roller and an upper roller, and the upper roller that mainly comes into contact with the toner image transferred onto the copy paper is a thermal roller that has a heater inside.
The lower roller is a pressure roller that is pressed against the heat roller. Normally, after the power is turned on, when the temperature at the temperature detection position of the ten rollers reaches a predetermined temperature, the ready lamp that indicates that copying is possible lights up, and in this state, the print switch is turned on. When is pressed, the drive motor rotates and is energized for the first time. The reason for starting the simultaneous rotation of the drive motor as late as possible in this way is to avoid operating the device as much as possible when it is not needed.

Here, the heat fixing roller is equipped with a temperature detection means on the upper roller, and after a predetermined temperature is detected by the detection means, a temperature control circuit is used to maintain the predetermined temperature. controlled. Normally, the above rollers are controlled to a 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 may be difficult to control the temperature to the specified temperature for the following reasons. Become.

As mentioned above, the heat fixing roller has a built-in heater only in the bottom two parts, the upper part of the inner part of the part, and the upper part of the part. And the Lord and 1. It is transmitted from the contact area between the upper roller and the lower roller to the lower [J-ra]. However, since neither roller rotates to the ready lamp ONR, the two contact portions are always the same. Therefore, even when the upper roller reaches a predetermined temperature, the temperature of the lower roller other than the above-mentioned contact portion remains close to the ambient temperature.
．． In this state, when the print switch is pressed to enter the copying process, the heat fixing roller rotates as the aforementioned drive motor rotates. At this time, the upper roller, which has risen to a predetermined temperature, comes into contact with the lower roller, which is approximately at the ambient temperature, and therefore a large amount of heat is removed. Still, under normal conditions and conditions fd ura f)
ii: It is possible to maintain the temperature of the upper roller at a predetermined temperature by increasing the input to the heater in the upper roller using the temperature control circuit of the heat fixing roller.

However, 1-1 If the ambient temperature is low or the power supply voltage is lower than the specified voltage, it is not possible to supply the same amount of heat as the heat taken away even if the input to the heater is increased as much as possible. In some cases, the temperature of the upper roller inevitably falls not only below a predetermined temperature but also below the lower limit temperature at which fixing is possible, which is lower than that of the upper roller. Therefore, even if the copy paper holding the transferred toner image on its surface passes through this heat fixing roller, the fixing of the toner image is incomplete.

The present invention has been made in view of the above problems, and even when the ambient temperature is low or in the three situations where the electric power is low, the above-mentioned heat fixing is performed before the Resophy lamp is turned on, that is, before the copying is possible. This is characterized in that the lower (pressing) roller is warmed in advance by rotating the roller. In fact, the present invention not only preheats the contact roller before copying is possible, but also preheats the contact roller for a predetermined period of time after copying is possible.
The present invention is characterized in that when the copying interval is 7 or more, the roller is rotated for a certain period of time t2 or -a certain number of times to suppress the temperature drop of the pressure roller as much as possible.

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

FIG. 1 is a sectional side view showing a heat fixing roller according to the invention at 21'. In the figure, the upper roller 1 is a heat roller equipped with a heater 2 inside, and the lower roller 3 is a pressure roller that is pressed against the heat roller 1 with a moderate pressure. Consisting of 0 rollers 1,
3 is rotated in the direction of the arrow, the incoming copy paper 4 is sandwiched between the rollers 1 and 3, and the toner image 5 formed on the upper surface of the roller 1 is fixed by the heat of the heat roller 1. The rollers 1.3 are driven by rotation of a main motor (not shown).

FIG. 2 is a circuit diagram for driving the heater 2 of the heat roller 1, and shows the set temperature T of the surface of the heat roller 1, (18
0°C) of the present invention. Reference numeral 6 in the figure denotes a temperature detection element that is attached to the surface of the heat roller 1 shown in FIG. 1 and detects the surface temperature of the heat roller 1, and is, for example, a thermistor whose resistance value decreases as the temperature increases. The thermistor 6 is connected in series with the resistor R3, and a voltage of 10 V is supplied between it and the ground.

Resistors R+ and R2 are connected in parallel to this series connection circuit of the thermistor 6 (resistance R4) and resistor R3.

Further, reference numeral 7 is a comparator for maintaining the heat roller 1 at a set temperature T1, and the set temperature T, (1,8
The resistance R1 has a reference value of 0℃). Further, the signal is supplied to the -1- side terminal of the comparator 7. Here, for example, if the set temperature R3 is selected to be 180° C. or higher, the output of the comparator 7 is inverted to 'L' when the set temperature becomes 180° C. or higher (or equal to).

If the temperature is below the set temperature T, the output of the comparator 7 is "T(").

The output of this comparator 7 is supplied to a set input terminal of a flip-flop 8, and a flip-flop 70. The flip-flop 8 is set when the output of the upper layer comparator 7 is ``L''.The reset input of the flip-flop 8 is supplied with an initial reset signal 1.R, which is output when the copying machine is powered on. The output Q of this flip-flop 8 is supplied to the base of the transistor 10 through the three-man powered or game 1 and 9.1 The transistor 10 is the main motor for rotating the main motor M. It is a switching element for supplying a voltage of 10 V to the relay 11. That is, when the base of the transistor 0 becomes "H", the transistor 10 becomes conductive and the relay 1
1 is energized and its contact is turned on, causing the main motor M to rotate.

Further, the set output Q of the flip knob 8 is supplied to one input terminal of the two-man gate 12. The output of the AND gate 12 switches the transistor 13 via the OR gate 11. This transistor 13 is a lamp 1 indicating a ready state (copyable state).
4 blinks, and if it is ON, ready lamp 1 is activated.
4 is lit.

The output of the comparator 7 is supplied to the base of the transistor 150 and drives the heater control circuit 16.

The output of comparator 7 is H''', that is, the set temperature T+(1
. This increases the temperature of the heat roller 1,
When the set temperature is reached, power supply to the heater 2 is stopped. The other input terminal of the AND gate 12 has a copy 2 "
A motor drive signal from the control circuit 17 is supplied.

Copying process control circuit] 7 is a print switch 1
8 performs well-known copying control, and when driving the main motor M, a drive signal 1) ("H") is output to the OR gate 9. The copying process control circuit 17 executes copying control in response to the operation of the cylinder switch]8, but if the copying is possible (ready) state, that is, the heat roller 1 has not reached the set temperature T1, the copying control circuit 17 executes the copying control in response to the operation of the cylinder switch ]8. Never run.

Further, a time signal from a timer circuit 19 is input to another input terminal of the OR gate 9.

The timer circuit 19 has a set input terminal (S) supplied with the gate output from the AND gate 2, and a reset input terminal (R) supplied with the gate output from the AND gate 12 via the inverter 20 and the OR gate 21. Supplied O': Kiorage-!・An initial reset signal XR, which is output when the power is turned on to the main body of the copying machine, is applied to the other input terminal 21. When a "H" signal is applied to the reset input terminal of the timer circuit 19, the output becomes "L", and when an "H" signal is applied to the set input terminal, the output becomes "H" signal at the time when the "H" signal is input. More.

At time, the output becomes "r," and after time t7, the output becomes "H" for time t2. In other words, when the timer circuit 19 is set, it counts the time for 41 hours "r," from the time when the 1-1 output is set, reverses after t1 time and becomes t2 time "JT", and repeats this until it is reset. I'll give it back. The times of t and t2 above are:
The time can be set so that the pressure roller 3 will not absorb heat from the heat roller 1 under adverse conditions and cause fixing failure, and may be set based on, for example, experimental results. Main power supply 0N-
If ftt, the initial reset signal "i L"
R8 ("H") is output, and the flip-flop 8 is reset. Father, the timer circuit 19 is also reset at the same time. By being reset, the flip-flop 8 supplies this reset output Q to one input terminal of the anti-games 1 and 9. With this power supply 0)NK, the output of the comparator 7 becomes "H", and power is supplied to the heater 2 of the heat roller 1 by the comparator 7 and the heater control circuit 16 to maintain the heat roller 1 at the set temperature T. temperature control is performed. By being reset, the flip-flop 8 supplies its reset output Q to the transistor 10 via the OR gate 9, making the transistor 10 conductive. As a result, the relay 11 operates, causing the main motor M to rotate, thereby rotating the heat roller 1 and the pressure roller 3. Due to this rotation, the temperature of the heat roller 1 gradually rises, and the pressure roller 3 also gradually rises at a temperature lower than that of the heat roller 1.

When the surface temperature of the heat roller 1 reaches the set temperature T,
The output of the comparator 7 is inverted from "J" to "L", and the flip-flop 8 is set. When the flip-flop 8 is set, the set output Q is passed through the AND gate 12 to The light turns on and the copy ready state is displayed.At this time, the reset output Q changes from ゝゝH“ to ゝゝL.
'', the transistor 10 becomes non-conductive, stops the rotation of the main motor M, and stops the rotation of the heat roller 1 and the pressure roller 3. Also, the output of the comparator 7 changes to . By becoming “L”, heater control circuit 1
At G, drive of heater 2 is stopped. Then, control is executed to maintain the heat roller 1 at the set temperature T1.

” If you operate the print switch 18 in the double state,
The copying process control circuit 17 executes copying control since it receives the copyable state signal.

Then, by outputting the drive signal of the main motor M,
Transistor 10 is made conductive via OR gate 9, and main motor M is driven. As a result, the heat roller 1 and the pressure roller 3 are rotated to fix the toner image on the copy paper 4j-2). In this case, the pressure roller 3 has been rotated in advance until it reaches the set temperature T1, and the entire roller is sufficiently preheated. Therefore, even if the heat roller 1 is rotated in accordance with copy control, the heat of the heat roller 1 is not absorbed by the pressure roller 3. Therefore,
The heat roller 1 does not undergo sudden temperature changes, and the heater control circuit 16 can always maintain the set temperature T1 even under low temperature conditions or low voltage conditions.

On the other hand, if the flip-flop 8 is set, the AND gate 12 is in the operating state, and the print switch 1
If 8 etc. are not operated, the timer circuit] 9 will be incremented seven times. This timer circuit 19 starts at t from the time it is set.
For 1 hour, the output is "r," and the main motor relay 11 is not energized. ○And after t3 hours,
The output of the timer circuit 19 is reversed to "H", the main motor is driven, and the heat fixing roller 1 is rotated. The rotation time at this time is t2 time when the output of the timer circuit 19 becomes "H". This means that when the copying machine is set up and the copying interval becomes a considerable period, 1
- Preventing heat from the heat roller 1 from being taken away by the pressure roller 3 when copying is started after the temperature of the heat roller 3 falls. Therefore, if the copyable state is set and no copying operation is performed, the heat fixing roller 1. ．． Output within 122 hours” L
", "H". Then, when the print switch 18 is operated, one timer circuit is turned on and the heat fixing roller is driven according to a drive signal from the copying process control circuit 7. Sane Ru.

Further, the timer circuit 19 is set, and if the print switch 18 or the like is operated within the tl time, the AND gate 12 is closed and the timer circuit 19 is reset. Therefore, t
If the print switch 18 is operated within one hour, the heat fixing roller is driven by the copy process control circuit 17 without rotating.

Incidentally, the timer circuit 19 is set and after t7 hours, its output is reversed to "H", thereby causing the main motor M to reach t.
Although the main motor M is driven for two hours, the number of rotations of the heat fixing roller may be counted and the driving of the main motor M may be stopped after a certain number of rotations.

In the embodiment described above, the heat roller 1 is turned on at the same time as the power is turned on.
and the pressure roller 3 are rotated, but when the copy is ready, the waiting time until the ready lamp 13 is turned on becomes longer. Since it is also heated via the heat roller 1,
The rise time of the heat roller 1 becomes longer. By energizing the main motor M, many other devices also operate when they are not needed. In addition, it would be a pain for the user to ignore the sound at this time. Furthermore, copy i
((The above toner adheres to the heat roller in a small amount during fixing, and the melted material solidifies when the power is turned off. Therefore, if the heat fixing roller is rotated immediately when the power is turned on,
There is also the problem of scratches on both rollers -) 0 If the above-mentioned problems arise when using a copying machine, they can be solved by the following specific example. Figure 3 shows a circuit configuration that shows a specific example. ○This figure shows the fixing temperature T.
From the time when a certain temperature T2 (160° C.) lower than 1 is detected by the upper RL fixing roller, the heat fixing roller is rotated IL. , 21'21. in FIG. The same as ;: i+ is indicated by the same reference numeral, and its explanation will be omitted. The resistor 1'++r2 corresponds to the resistor R7 shown in FIG. 2 and is on one side of the comparator 7.

In addition, the comparator 22 changes the output from ゜L/I to \ when the surface temperature of the heat roller 1 reaches, for example, 160°C (T2).
\H" (is inverted and drives the main motor M. Therefore, each resistor should be set so that the comparator 22 will respond. The output of this comparator 22 is connected to one input terminal of the AND gate 23. A flip-flop 8 is connected to the other input terminal of the AND gate 23.
A reset output Q is supplied. This anime game-1
- The output of 23 is supplied to the base of the transistor 10 via the OR gate 9 as shown in FIG.

When the power of the copying machine is turned on in the circuit configuration described above, the flip-flop 8 is turned on and the timer circuit 1 is turned on.
9 is also reset. Also, the comparator 7 is connected to the heat roller 1
Since the temperature of has not reached the set temperature T, its output is \H'', and the heater 2 is driven by the heater control circuit 16 to heat the heat roller 1〇-Meanwhile, the temperature of the comparator 22 reaches the temperature T2 If the output does not reach \\L
/', the main motor relay 11 is not energized, the main motor is not rotated, and the power supply is O.
At the same time as N, the heat roller 1 and the pressure roller 3 are not rotated.

After that, the amount of heat ~1 is heated by the heater 2, and the temperature T
2, the output of the comparator 22 becomes \H, and since the reset output Q of the flip 70 knob 8, which was reset when the power was turned on, is ``H'', the AND gate 23 opens. conducts, the relay 11 is energized, the force 5 is applied, and the main motor M is driven.

Therefore, the temperature of the heat roller 1 and the pressure roller 3 is T2 (16
When the temperature reaches 0℃), it rotates. At this time, as the pressure roller 3 rotates, the heat of the heat roller 1 is absorbed by the pressure roller 3, and although the temperature rise of the heat roller 1 is reduced, the temperature of the pressure roller 3 as a whole also gradually rises.

Thereafter, as in FIG. 2, when the temperature of the heat roller 1 reaches T1, the rotation of the main motor M is stopped and the roller ], 30
Rotation stops. Further, the ready lamp 14 is lit to display the copy ready state.

As a result, when the print switch 18 is pressed, the copy T
The process control circuit 17 executes copy control, outputs a drive signal for the motor M, and rotates the motor.

Here, after turning on the power, both rollers 1 and 3 are not rotated,
When the temperature exceeds T2, the rotation is continued, and the rotation time of the rows 1 and 3 is shortened, and durability and noise can be minimized. In addition, the assimilated toner melts and rotates without causing any scratches on the surfaces of the rollers 1 and 3.
The amount of heat taken away by the side is small, and the set temperature T1 is reached\r
I can write down the time. In this case, although the preheating temperature of the pressure roller 3 is lower than that in FIG.
The temperature T2 is set at a rapid temperature drop of the heat roller 1 (with a certain distance from the set temperature T1), and the temperature T2 is set at a certain distance from the set temperature T1. If the L jam roller] and 3 are rotated, it becomes possible to control the temperature near the temperature T or below the lower limit temperature for fixing, even with the electric power that can be used during copying, thereby preventing fixing failures, etc. There is no need to worry about it at all.

In FIG. 3, as in FIG. 2, when the flip 70 knob 8 is set, the timer circuit 19 is set, and if no copying operation is performed within time t7 from the time of this setting,
The main motor relay 11 is energized, and the rollers 1 and 3 are rotated to suppress the temperature drop of the pressure roller 3.

As explained above, by the heat fixing roller of the present invention.

For example, you can either rotate both rollers while supplying a small amount of electricity, or set a temperature T2 that is slightly lower than the set temperature T, and when this temperature is reached, rotate the rollers to preheat the pressure roller side before copying is possible. This makes it possible to minimize the amount of heat taken by the cutout roller during copying, and to easily control the set temperature T of the heat fixing roller. ) or more, the roller rotates and the temperature of the pressure roller is kept from dropping, ensuring stable fixing at all times.

[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 eleven specific examples for implementing the present invention, and FIG. 3 is a circuit configuration diagram showing another specific example for implementing the present invention. . 1 Heat roller, 2 Heater, 3: Pressure roller, 4 Copy paper, 5 Toner image, 6: Thermistor, 7° set temperature i'
r[Output comparator, 11 Main motor relay, 1
4 Lettie Lang, 16 Heater control circuit, 17
Copying process control circuit, 19 timer circuit, 22 temperature T2
Detection comparator 0 Agent Patent attorney Aihiko Fukushi

Claims (1)

[Claims] 1. A heat fixing roller consisting of a heat roller equipped with an internal heat source and a pressure roller that is in pressure contact with the heat roller (with a detection element that detects the surface temperature of the heat roller). a temperature control circuit that drives and controls the heat source to control the heat roller to a set temperature based on the detection element; a drive means that drives both of the rollers; A heat fixing roller comprising: a control circuit for driving both rollers for a certain period of time or a certain number of times via the driving means. 2. The driving means rotates the heat fixing roller in advance before copying is possible. The heat fixing roller 03 according to claim 1, further comprising a roller drive control circuit for stopping the rotation by a signal based on a set temperature of the heat roller. Claim 2, characterized in that the roller is driven by detecting electrolytic erosion.
Thermal fixing roller described in section. 4. The heat fixing roller according to claim 2, wherein the roller drive control circuit drives the roller based on detection of a temperature slightly lower than a set temperature of the heat roller.