JPS61188571A - Fixing device - Google Patents

Abstract

PURPOSE:To shorten a waiting time and extend the life of a roller by detecting the surface temperature of a hear roller, maintaining the heat roller's surface temperature at a temperature capable of fixing, and detecting a pressing and contacting roller to control the rotation of both the rollers. CONSTITUTION:A cylindrically formed heat roller 1 has a heater lamp 2 disposed at an inside thereof. To the roller 1, a cylindrical pressing and contacting roller 3 contacts under pressure. The rollers 3, 1 constitutes a thermal fixing roller. To the rollers 1, 3, temperature detecting elements 4, 5 for detecting a surface temperature are disposed in opposite. The elements 4, 5 are respectively connected in series with resistances R1, R6. Voltages to be detected Va, Vd are compared with a reference voltage and fed to a control circuit 8. The circuit 8 maintains the surface temperature of the roller 1 by a driver 12 and relays 13, 14 at a temperature capable of being fixed based on the detected surface temperature, and controls a rotation of the roller 3. In such a way, a waiting time till a waiting condition can be shortened and a life of the roller itself can be extended.

Description

[Detailed description of the invention] Technical fields> The present invention relates to a fixing device for fixing an unfixed image.

<Prior art> In an electrophotographic copying machine, an image formed on a recording medium is transferred to a transfer material that is sent as needed, and in order to fix the image on this transfer material, the transfer material after transfer is transferred. It is separated from the recording medium and transported to the fixing section. The image on the above transfer material is
The image is fixed on the transfer material by passing through the fixing section. A thermal fixing roller is widely used as a device for fixing images.

The heat fixing roller is composed of a pressure roller that is provided with a heater lamp such as a halogen lamp as a heat source in at least the side of the roller that contacts the unfixed image, and that presses against the roller with an appropriate pressure.

A roller (heat roller) having a heater lamp inside is controlled to have a temperature at which an image can be fixed on the roller surface by controlling power supply to the heater lamp. That is, a temperature/detection element is brought into contact with the surface of the heat roller, and power supply control to the heater lamp is executed based on a signal from the temperature detection element.

In the fixing roller as described above, after turning on the power of the copying machine, it is necessary to wait until the temperature reaches a temperature that allows fixing (warm-up time). Here, unless a heater lamp or the like is installed in the roller that comes into pressure contact with the heat roller, the surface temperature of the heat roller will drop significantly when the fixing roller rotates during a copying operation.

In order to prevent this, it is necessary to heat the pressure roller at the same time. For example, the surface temperature of the heat roller should be slightly lower than the fixing temperature (control temperature) (predetermined temperature >
When K is reached, the heat fixing roller is rotated and heat is transferred to the pressure roller, thereby preheating the pressure roller.

The rotation of the fixing roller is performed after a predetermined temperature, for example, at a certain time.
It is rotating for a while. This method is described in Japanese Patent Application Laid-Open No. 56-142.
It is disclosed in Publication No. 56.

However, according to the above-described method, since the rotation of the fixing roller is stopped regardless of the surface temperature of the pressure roller, it is conceivable that the surface temperature of the heat roller decreases significantly during the copying operation. For example, it is thought that the surface temperature of the heat roller decreases after jam removal, but if the temperature exceeds a predetermined temperature, it is not rotated, and at this time, the surface temperature of the pressure roller may decrease significantly.

In addition to the above-mentioned method, it has also been considered to unconditionally rotate the fixing roller for a certain period of time when the main power source of the copying machine is turned off again for jam processing or the like. In this case, it is effective to heat the pressure roller. However, even if the fixing roller is at a temperature that allows fixing, it is rotated unconditionally for a certain period of time, so the copying machine's standby state (Read
y,) (waiting time) becomes longer. Further, it is desirable that the rotation of the fixing roller be restricted as much as possible. In other words, since a considerable amount of pressure is applied between both rollers, the life of the rollers themselves is shortened as they rotate, and in particular, the fixing roller is rotated during copying operations.

<Purpose> An object of the present invention is to shorten the waiting time and the like in a heat fixing roller.

Another object of the present invention is to restrict the rotation of the heat fixing roller and extend the life of the roller.

<Example> FIG. 1 is a sectional view showing a heat fixing roller in the present invention. In the figure, 1 is a cylindrical heat roller, and a heater lamp 2 is provided inside the heat roller. The surface of the heat roller 1 comes into contact with the unfixed image on the transfer material, so it is coated with a material having good releasability for the unfixed image. For example, the surface of the heat roller 1 is coated with Tenron or the like. A cylindrical pressure roller 3 is pressed against the heat roller 1, and the pressure roller 3 and the seventh roller 1 constitute a heat fixing roller. Its surface is made of a highly elastic material such as silicone rubber so that it can be pressed with a sufficient width (butt width).

Each roller 1.3 of the heat fixing roller is provided with a temperature detection element 4.5 such as a thermistor in contact with it for detecting the surface temperature. These temperature detection elements 4 and 5
The rotation of the heat fixing roller and the heater lamp 2 are based on the output of
drive control is performed. An example of the control port configuration for this purpose is shown in FIG. The temperature detection element 4 is connected in series with the resistor R1 and is supplied with a voltage +V, and Va is supplied to the ÷ terminal of the comparator 6. One terminal of the comparator 6 is connected in series and is supplied with a certain reference voltage vb. is set to 0, so
When the detected voltage Va based on the temperature detection element becomes equal to or higher than the control temperature 11 on the surface of the roller 1, Va≧v
Each of the resistors R1 to R3 is appropriately set so that the resistance value b.

Furthermore, the detected voltage Va is supplied to the child terminal of another comparator 7, and the surface temperature T of the heat roller l reaches a predetermined temperature fT2 (a temperature slightly lower than the control temperature T1). 0 Therefore, one terminal of the comparator 7 has a divided voltage output c -! by the resistors R4 and R5. -L--v)
A second reference voltage R4+R5 voltage Vc is supplied. Therefore, when the surface temperature of the heat roller 1 becomes equal to or higher than the predetermined temperature 12, Va≧Vc
Resistors R4, R5, etc. are appropriately set so that.

The outputs of both the comparators 6 and 7 are input to a control circuit 8 consisting of an LSI. Control circuit 8#: R in advance
According to the controller lNK programmed in OM9, necessary data is temporarily stored in or read out from the RAM IO, and a control signal is output using the data. Further, the control circuit 8 internally stores necessary timers 11 and the like in the RAM I.
It may also be configured using O. The control circuit 8 controls the power supply to the heater lamp 2 based on the output from the comparator 6 in order to maintain the surface of the heat roller 1 at the control temperature Tl. In other words, the control circuit 8
outputs a signal for energizing the heater lamp relay 13 via the driver circuit 12 in order to supply the power supply VAC to the heater lamp 2 .

Furthermore, if the output of the comparator 7 is inverted from "L" to 'H', the voltage V supplied to the input terminal of the comparator 7
Since the relationship between a and Vc is Va≧Vc, the control circuit 84d outputs a signal to energize the main motor relay 14 via the driver circuit 12 in order to rotate the heat fixing roller. As a result, contact 14-I of relay 14 turns ON.
L, the main motor 16 is driven to rotate the fixing roller and heat the pressure roller 3.

On the other hand, the surface temperature of the pressure roller 3 is detected by the temperature detection element 5, and as shown in FIG.
hl and a child terminal of the voltage division ratio coverator 17 with the resistor R6. One terminal of the comparator 17 has a resistor R
7 and R8 partial pressure. Therefore, comparator I7
The output becomes #Hm when the voltage input to both terminals is Vd≧Ve. The reference voltage Ve is set to detect when the surface temperature "r□" of the pressure welding roller 3 reaches a predetermined temperature TO Resistors R6, R7 and R8 are set appropriately.Here, a predetermined temperature T of the pressure welding a-ra 3 is set.
O+ is set at a temperature higher than the temperature at which the heat of the heat roller is absorbed by the pressure roller 23 at the initial stage of copying and no fixing failure occurs. For example, when the heat roller 1 reaches the temperature T2, the rollers 1 and 3 are rotated and the pressure roller 3 is heated. At this time, if TO+ is set to the temperature at which the pressure roller 3 is heated after rotation for a predetermined time, good.

The operation of the heat fixing roller described above will be explained. When the main power of the copying machine is turned on, the control circuit 8 energizes the heater lamp relay 13. As a result, the contact +a-1 of the heater lamp relay 18 is turned on, and the heater lamp 2 is energized. This energization heats the heat roller 1, and when the roller surface temperature reaches 12 or more, the output of the comparator 7 becomes "H"'. Therefore, the control circuit 8 energizes the main motor relay 14 . When the main motor relay 14 is energized, its contacts 14-1
is ONL, and as the motor 16 rotates, the heat fixing roller rotates.

When the roller 1.3 rotates, the heat of the heat roller 1 is transferred to the pressure roller 3, and the pressure roller 3 is heated. The temperature of the roller 3 is set to be higher than the temperature 'rot.After a predetermined period of time has elapsed since the start of rotation, the control circuit 8 de-energizes the main motor relay 14 and stops the rotation of the roller 3 and the roller 3. Then, when the surface temperature of the heat roller 1 reaches 11 or more, the heater lamp 20 is de-energized.In other words, the heater lamp 2 is energized according to the temperature detection output of the comparator 6, and the surface temperature of the heat roller 1 is is maintained at the control temperature Tl. When the heat roller 1 reaches the control temperature Tl, the copying machine becomes ready for copying, and the copying operation is started by operating the copy switch.

On the other hand, if paper jams during the copying operation of the copying machine, the jammed paper is removed. In this case, the main body of the copying machine is opened and power supply to the heater lamp 2 is temporarily stopped. Therefore, it is thought that the surface temperature of the heat roller 1 decreases. Then, when the jam processing is completed, power supply control to the heater lamp I is started. Here, if the copying machine is temporarily stopped due to a jam or the like as described above, it is predicted that the surface temperatures of the heat roller 1 and the pressure roller 3 will decrease. After this temporary stop, when the power is turned on again, the heat fixing roller is controlled according to the flow shown in FIG. That is, when the main power is turned on again after processing for jams, etc., the process jumps to step S1 in FIG. 3, and the surface temperature of the heat roller 10 is judged. At this time, if the temperature T of the heat roller 1 is lower than the control temperature T1 and equal to or greater than the predetermined temperature T2, the process proceeds to step S2, and the surface temperature of the pressure roller 3 is judged. If the surface temperature To of the pressure roller 3 is equal to or higher than the predetermined temperature 701, the process advances to step S3 and waits until the surface temperature T of the heat roller 1 becomes equal to or higher than 11. Then, if the surface temperature T of the heat roller 1 becomes T≧T1, the process proceeds to step S4,
A message such as "Ready" will be displayed indicating that the copying machine is in a standby state.

In step S2 above, the surface temperature T of the pressure roller 3
If o is less than or equal to TO+, the process proceeds to step 5 and a timer is set. This timer is for rotating the heat fixing roller for a certain period of time. The set time t1 of the timer is different from the time t, which is rotated for a certain period of time if the heat roller 1 reaches a temperature of 12 or higher when power is initially supplied to the copying machine. In particular, when the power is turned on again, the temperature of the pressure roller 3 is thought to be higher than that at the initial stage, and the time t1 of the timer is set to 1≦[゛.

After setting the timer, the timer counts the time;
The process moves to step S6, and the heat fixing roller stops rotating. In other words, the main motor relay! 4 is energized and its contact 14-
1 turns ON, the motor 16 rotates and the rollers 1 and 3
Rotate. Then, when the timer counts a predetermined time, the process moves from S7 to S8, and the rotation of the fixing roller is stopped. After the rotation stops, the process jumps to step S3, and after confirming that the surface temperature T of the heat roller 1 is higher than T1, a "Ready" message indicating the standby state of the copying machine is displayed (S4).
will be carried out.

On the other hand, if the surface temperature T of the heat roller 1 is below the predetermined temperature T2, the process jumps from S1 to S9, and it is checked whether the surface temperature To of the pressure roller 3 is above the temperature 101. In this case, if the surface temperature &To of the pressure roller 3 is To≧TO+, the process jumps to step S3 described above. However, the surface temperature T of the pressure roller 3.

If To<Tol, the process proceeds to step S10, and it is checked that the surface temperature T of the heat roller 1 reaches a predetermined temperature T2. Then, heat the roller to a predetermined temperature of 12 or higher! When the surface of is heated, proceed to step 511 and again.
Surface temperature T of pressure roller 3.

is checked. Here, since the heat fixing roller is not rotated, the surface temperature To of the pressure roller 3 is normally To
("r 01. Therefore, step S
5, as described above, a timer for rotating the heat fixing roller for a predetermined time t1 is set, and the heat fixing roller is rotated.

Further, if the heat roller 10 surface temperature T is equal to or higher than the control temperature T1, the temperature jumps from SI to SI2, and the pressure roller 3
It is checked whether the surface temperature To of is To≧TO+. Therefore, the surface temperature To of the pressure roller 3 is To≧
If it is TOI, the process advances to step S4 and displays the 'Ready' state. However, if the surface temperature To of the pressure contact roller 3 is To<To+, the process advances to step S5 and sets a timer. That is, the heat fixing roller Rotate for the specified time on the timer.

As described above, when the copying machine is temporarily stopped and the main power is turned on again, the surface temperature TO of the pressure roller 3 reaches the predetermined temperature TO.
+, if TO≧TO+, the rotation of the heat fixing roller is prevented, and the surface temperature T of the heat roller 20 is T1.
If the above is the case, the copying machine is immediately set to the Ready state. Therefore, rotation of the fixing roller can be suppressed, and roller 1
, 3 can be extended. Further, if the surface temperature T of the heat roller I is T1 or more, the copying machine immediately enters the Ready state, so that the waiting time of the copying machine after the power is turned on again can be shortened.

Note that if the surface temperature TO of the pressure roller 3 is lower than the temperature TQI, the heat fixing roller is rotated for a predetermined time t1. However, if the surface temperature TQ is close to the temperature TO+, the pressure roller 3 can be sufficiently heated to the predetermined temperature 'rot even if the rotation time of the heat fixing roller is reduced. For this purpose, a comparator 18 is provided as shown in FIG. 2 to detect the surface temperature TO2 of the pressure roller 3. This temperature TO2 is a temperature slightly lower than the temperature TOI, for example, I O'~20
The temperature is set to about 10°. Comparator 18 above
A reference voltage V for detecting the temperature TO2 is connected to one terminal of the
f is supplied, and the detected voltage Vd based on the temperature detection of the pressure roller 3 is supplied to the terminal 0. Therefore, by appropriately setting the resistance R9 and RIG, the pressure roller 3
When the surface temperature To becomes the temperature TO2, comparator 1
The output of 8 becomes "H".

Therefore, 82 of the flow in Figure 3. In S9 and S12, if the surface temperature TQ of the pressure roller 3 is below the temperature TO+, then it is determined whether the temperature TO is above the temperature 702. In this case, if the temperature of the pressure roller 3 is higher than TO2, the time for rotating the heat fixing roller is shortened.

That is, the timer time t2 is set to tl)t2, the timer is set, and the heat fixing roller is rotated for the timer set time t2. Conversely, the temperature of the pressure roller 3 is TO
If it is less than or equal to 2, the process moves to Step S5, as described above, and the heat fixing roller is rotated for a predetermined time tl.

With this, it is not necessary to always rotate the heat fixing roller for a predetermined period of time, and there is an effect that the rotation of the heat fixing roller can be further suppressed.

and a temperature detection means for detecting the surface temperature of the pressure roller, and if the surface temperature of the pressure roller is equal to or higher than a set temperature, the rotation of the heat fixing roller is prevented, and the surface temperature of the pressure roller is If the temperature is below the set temperature, the heat fixing a-ra is rotated for a fixed period of time.
The rotation of the heat fixing roller is suppressed and the life of the roller itself can be extended.In addition, if the surface temperature of the pressure roller is higher than the set temperature, the rotation of the heat fixing roller is prevented and the temperature at which the heat roller 1 can fix is increased. When this happens, the device enters a standby state, and the waiting time to reach this standby state can be shortened.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a specific example of the heat fixing roller according to the present invention, FIG. 2 is a block diagram showing the control circuit configuration of the heat fixing roller shown in FIG. 1, and FIG. 3 shows the control procedure shown in FIG. 2. OI which is a flowchart: Heat roller 2: Heater lamp 3: Pressure roller 4, 5: Temperature detection element 6
, 7, 17.18 = comparator 8: control circuit 13
: Heater lamp relay 14: Main motor relay 16
: Motor − Agent Patent attorney Aihiko Fukushi (and 2 others) Figure 1 −; ■

Claims (1)

[Scope of Claims] 1. A heat fixing roller comprising a heat roller having an internal heat source for fixing an unfixed image formed on a transfer material, and a pressure roller that is pressed against the heat roller. ,
A first detection means for detecting the surface temperature of the heat roller, a second detection means for detecting the surface temperature of the pressure roller, and a signal from the first detection means can fix the temperature of the heat roller surface. It is characterized by having a temperature control unit that maintains the temperature, a drive unit that rotates both of the rollers, and a roller drive control unit that controls the drive unit in response to detection of a predetermined temperature by the second detection unit. Fusing device. 2. The fixing device according to claim 1, wherein the roller drive means rotates both rollers for a certain period of time when the second detection means detects a temperature lower than a predetermined temperature. 3. The roller driving means rotates both rollers for a time shorter than the predetermined time by detecting a temperature below a predetermined temperature and close to this temperature by the second detecting means. fixing device.