JPH05241473A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the nipping part of fixing rollers in a standby state from being left locally deformed by rotating the fixing rollers by specific amounts so that the press-contacting part of the fixing rollers when a specified time lapses in a standby mode, is, at least, moved to the other places, whenever the specified time lapses in the standby mode. CONSTITUTION:The fixing rollers (a heating roller 42 and a pressure roller 43) are set in the standby mode where they are preliminarily heated to the prescribed temperature of a fixing temperature or below, in a stationary state, so that starting-up up to the fixing temperature in use is quickened, and fixing can be executed without having a waiting time. However, whenever the specified time lapses in the standby mode, the rollers 42 and 43 are rotated by the specific amounts, so that the press- contacting part 48 of the fixing rollers 42 and 43 when the specified time lapses, is, at least, moved to the other places. Before the rollers 42 and 43 are preliminarily heated and the local deformation of the press-contacting part 48 is fallen into a habit by pressurization and the preliminary heating, the press-contacting part 48 is moved to the other places, and the deformation at the press-contacting part 48 before being moved, can be restored in a very short time. The fresh deformation of the press- contacting part 48 can be restored in a short time by the movement of the press- contacting part, at the time of fixing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image or the like formed on a sheet by pressing and heating by an image forming device such as a copying machine or a laser beam printer adopting an electrophotographic system. It is a thing.

[0002]

2. Description of the Related Art It takes time for a fixing device of this type to rise to a predetermined fixing temperature. To shorten this rise time and reduce or eliminate the waiting time,
It is known that the fixing roller is preheated to a predetermined temperature equal to or lower than the fixing temperature in a standby mode in which the power is turned on and is not in use, so that the fixing roller can quickly rise to the predetermined fixing temperature during image formation. Has been.

[0003]

With the widespread use of copying machines and the like, the usage status of each user has become diversified and has become commonplace.

For this reason, in a store where a copying machine is set up for use by a customer, a business office where the copying machine is used, etc., even in times such as nighttime when the frequency of use is low and conditions are prepared, it is prepared for emergency use. It is said that the power of the copying machine is turned on and kept in a standby state.

However, when the copying machine or the like is used from the standby state as described above, an abnormal noise is sometimes generated near the fixing device.

As a result of repeated experiments conducted by the inventor of the present invention, it was found that this occurs frequently when the fixing roller is left in a standby state where it is stationary in a preheating state for a long time.

This is because the pressure-bonded portions which are deformed by the pressure-bonding of the fixing rollers are apt to be in the deformed state due to the pressurization and the heating, which is suddenly released even when the pressure-bonding is released by the rotation of the fixing roller. It is considered that the cause is that the fixing roller is not deformed and is rotated while being locally deformed.

The present invention has been made on the basis of such a new finding of the present inventor. The nip portion remains locally deformed by a long period of time while the fixing roller is stationary in the standby state. It is an object of the present invention to provide a fixing device capable of preventing the above problems and solving the above-mentioned conventional problems.

[0009]

In order to achieve the above-mentioned object, the present invention has a heat source in at least one of a pair of fixing rollers which are in pressure contact with each other, and has a temperature not higher than the fixing temperature when the fixing rollers are stationary. In a fixing device having a standby mode in which preheating is performed, the fixing roller is rotated by a predetermined amount every time a predetermined time elapses in the standby mode so that the pressure-bonding portion of the fixing roller at this point moves to at least another part. It is characterized by that.

[0010]

According to the above construction of the present invention, the fixing roller is set in the standby mode in which the fixing roller is preheated to a predetermined temperature lower than the fixing temperature in a stationary state, so that noise, fatigue, wear, etc. due to useless rotation driving are caused. Without this, the rise to the fixing temperature at the time of use is accelerated, and fixing can be performed without waiting time, but every time a predetermined time elapses in the standby mode, the pressure-bonding part of the fixing roller at least moves to another position. As described above, the fixing roller is rotated a predetermined amount, and before the fixing roller is preheated, local pressure deformation of the pressure bonding portion is caused by the pressure and the preheating. Deformation at the pressure-bonding part can be recovered in an extremely short time, and the deformation at the new pressure-bonding part is maintained only for the predetermined time or less. Department transfer It can be made to be further recovered in a short time due to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a copying machine will be described below with reference to the drawings.

As shown in the overall structure of FIG. 1, the copying machine of this embodiment is provided with a photosensitive drum 1 which is driven to rotate counterclockwise in the substantial center of the copying machine body.

An eraser lamp 2, a charging charger 3, a developing device 4, a transfer charger 5, a separation charger 6, and a cleaning device 7 are sequentially arranged around the photosensitive drum 1 in the rotation direction of the photosensitive drum 1.

The photosensitive drum 1 is provided with a photosensitive layer on the surface thereof, and the photosensitive layer is passed through a position facing the eraser lamp 2 and the charging charger 3 to be uniformly charged by receiving these functions. It

The charged photoreceptor layer is imagewise exposed by the optical system 11 to form an electrostatic latent image on the surface.

The optical system 11 is installed below the platen glass 12 so as to scan an original image, and is composed of a light source 13, movable mirrors 14, 15 and 16, a projection lens 17, and a fixed mirror 18. There is.

The light source 13, the movable mirrors 14, 15 and 1
6 moves to the left at a speed of V / m (where m is a copying magnification) with respect to the peripheral speed V of the photosensitive drum 1 (constant regardless of equal magnification or variable magnification), and the movable mirrors 14 and 15 move. It is driven to move to the left at a speed of V / 2m.

The electrostatic latent image formed on the surface of the photosensitive layer of the photosensitive drum 1 is developed with toner by the developing device 4 in the next stage to be visualized.

The visualized toner image on the surface of the photosensitive drum 1 is transferred through a timing roller 19 or the like so that the transfer sheet 21 is conveyed with its front end aligned with the toner image.
The image is transferred onto the upper surface by the transfer charger 5.

The transfer sheet 21 after transfer is separated from the photosensitive drum 1 by the separation charger 6 and is conveyed to the conveyor belt 22.
Are conveyed to the fixing device 23.

Transfer sheet 2 sent to fixing device 23
The sheet No. 1 is discharged onto the sheet discharge tray 24 after undergoing the toner image fixing process.

On the other hand, the surface of the photosensitive drum 1 after the transfer is cleaned of the toner and charges remaining on the surface by the cleaning device 7 and the eraser lamp 2 to prepare for the next copying process.

The transfer sheet 21 includes first and second sheet feeding units 33 and 34 having cassettes 31 and 32 which can be attached to and detached from the copying machine body, and a sheet feeding table 3 which also serves as an installation table of the copying machine.
5, each of which is loaded in each of the third and fourth sheet feeding units (not shown) having a detachable cassette, and the sheet feeding units 33, 34, ... Are selectively driven by a sheet feeding selection signal. By doing so, it is sent into the main body of the copying machine.

The specific structure of the fixing device 23 is as shown in FIG. This fixing device heat-fixes a toner image by applying pressure and heat, and includes a heating roller 42 having a fixing heater 41 for heating as a heat source, and a heating roller 42 which is pressed against the heating roller 42 and is fixed therewith. It has a pressure roller 43 forming a roller pair, and an oil application roller 44 which is in pressure contact with the heating roller 42 and applies silicone oil for mold release to the outer peripheral surface of the heating roller 42.

The rotating shafts of the heating roller 42 and the pressure roller 43 are connected to each other via a power transmission means such as a gear. Therefore, the rotation of the pressure roller 43 in the arrow direction causes the heating roller 42 to move in the arrow direction. To be rotated.

The rotation of the heating roller 42 causes the oil application roller 44 to rotate in the direction of the arrow.

The pressure roller 43 has a silicone rubber layer 4
3a and a Teflon layer 43b that covers the outer peripheral surface of the silicone rubber layer 43a.

The heating roller 42 has a mandrel 42a and a silicon rubber layer 42b covering the outer peripheral surface of the mandrel 42a.

A thermistor 45 is provided on the silicone rubber layer 42b so as to be in sliding contact with the heating roller 42 to detect the surface temperature of the silicone rubber layer 42b.

The oil applying roller 44 is composed of a single layer of silicon rubber, and one end of an impregnating member 46 made of felt comes into contact with the surface of the roller, and the other end of the impregnating member 46 is immersed in a silicon oil reservoir 47. There is.

As a result, the silicone oil stored in the silicone oil storage layer 47 is impregnated in the impregnating member 46 and applied to the surface of the oil applying roller 44, and then is conveyed by the rotation of the oil applying roller 44 and is heated by the heating roller 42.
Applied to the surface of.

Separation claws 49 and 50 are provided at the outlets of the pressure-bonding portions 48 of the heating roller 42 and the pressure roller 43.

The pressure roller 43 is rotationally driven in the direction of the arrow by the driving force supply means 52 using the fixing motor 51 (FIG. 1). This driving force supply means 52 is the first CP
It is controlled by U53, and the driving force is turned on and off.
For example, the rotational speed switching control is performed by the voltage control rotational speed switching control.

The temperature signal from the thermistor 45 is given to the first CPU 53, and a signal for controlling the lighting of the fixing heater 41 inside the heating roller 42 is given from the first CPU 53 to the power supply means 54.

The fixing heater 41 is, for example, a halogen lamp or the like and is energized by the power supply means 54.

FIG. 3 shows a block diagram of a control circuit using the first CPU 53.

The various display sections and the key matrix section use a decoder to time-divisionally share the CPU 53.
Is taken into.

The CPU 53 controls the operation of the copying machine, and the ten key 1 on the operation panel of the copying machine (not shown).
01, print key 102, clear / stop key 10
3, a group of operation keys such as the main switch 104 and the optical system 1
1 fixed position switch 105 for detecting the fixed position, timing switch 106 for outputting a drive signal for the timing roller 19, transfer sheet size detection switches 111-117 for the first and second sheet feeding units 33, 34, transfer Sheet color detection switches 118 to 121, and a detection switch group such as empty detection switches 122 and 123;
It is connected via the decoder 56, and is also connected to a display device 124 for displaying the numerical value input by the ten-key pad 101 as the number of copies in the normal mode.

The first CPU 53 also feeds papers 33, 34.
.. The paper feed display 127 for displaying the selection state of the decoder 1
28, and the thermistor 45 is connected via an A / D converter.

The first CPU 53 outputs operation control signals for the motors, clutches, chargers, etc. in the main body of the copying machine to control the above-mentioned image forming sequence, and the RAM 125 with a battery backup and the paper feed tray 35.
The second CPU 126 for controlling the operation of is also connected through the bus line.

The second CPU 126 has size detection switches 130 to 137 for detecting the size of the transfer sheet in each of the above-mentioned third and fourth sheet feeding units, color detection switches 138 to 141 for detecting the color of the transfer sheet, and The empty detection switches 142 and 143 are connected, and the drive control signals for the paper feed rollers in the third and fourth paper feed units are output.

The first CPU 53 is the second CPU 126.
While exchanging signals with and between the control unit and the control unit, selection control of the sheet feeding unit and control of the copying operation shown in the flowcharts of FIGS. 4 to 5 are executed. These controls will be described below.

FIG. 4 is a schematic flowchart of the main control of the first CPU 53. When the first CPU 53 is reset and the program starts, step # 100.
First of clearing RAM, setting various registers, etc.
Initialize the CPU 53 and initialize the apparatus to the initial mode.

Next, it is built in the first CPU 53,
The value starts an internal timer which has been set in advance by initialization (step # 200).

Subsequently, a fixing temperature adjusting process (step # 300) for controlling the fixing temperature shown in the flowchart, and a fixing motor driving process (step # 300) for controlling driving of the heating roller 42 and the pressure roller 43 which are a pair of fixing rollers. # 400),
When the subroutines of the copy operation process (step # 500) and other processes (step # 600) are sequentially called, and when the processes of all the subroutines are completed,
One routine is ended after waiting for the end of the initially set internal timer (step # 700).

The time length of this one routine is used to count the various timers that appear in the subroutine.

The values of various timers are set depending on how many times this one routine is repeated, and the end of the timer is determined by the number of times this setting is repeated.

The fixing temperature control processing subroutine, the copy operation processing routine, and other processing subroutines are well known and will not be described.

The fixing motor drive processing subroutine of FIG. 5 is shown. First, in step # 401, it is determined whether or not the copying machine body is in the copying operation. If the copying operation is in progress, the standby time timer and the fixing rotation time timer are reset (step # 402), and the process proceeds to step # 403.
Rotate the fixing motor and return.

If the copy operation is not in progress in step # 401, the process proceeds to step # 405 and it is determined whether or not it is in a standby state. In other words, it is determined whether or not the warm-up of the fixing device is completed and the copy start can be accepted.

If it is in the standby state, it is determined in step # 406 whether or not the standby time timer is set.

If the standby time timer is not set, the process proceeds to step # 411 to determine the status of the fixing motor. If the fixing motor is off here, it means that the copying is completed or the warm-up is completed. Therefore, the standby time timer is set to 2 hours (step # 412), and the fixing motor is turned off in step # 413 to perform the processing. To finish.

Next, when the standby time timer is set in step # 406, this standby time timer is counted up (step # 407), and then it is determined whether or not the standby time timer is finished (step # 408).

When the waiting time timer expires, 100 mse
The fixing rotation time timer of c is set (409), and the process proceeds to step # 403. This fixing rotation time timer is set on the condition that the current pressure-bonding portion of the fixing roller pair moves to another portion.

If the standby time timer has not expired in step # 406, the flow advances to step # 413 to turn off the fixing motor and terminate the processing.

If the fixing motor is not turned off in step # 411, the fixing motor is rotating in the fixing rotation time timer set, and the routine proceeds to step # 415, where the fixing rotation time timer is counted up, and step # 416. Determines whether the fixing rotation time timer has ended.

If the fixing rotation time timer has expired, the routine proceeds to step # 413, where the fixing motor is turned off to end the processing. If the fixing rotation time timer has not expired, the routine proceeds to step # 403 where the fixing motor is turned on. Keep the state and keep the rotation.

Returning to step # 405, if not waiting, warm-up is in progress. In this case, both the waiting time timer and the fixing rotation time timer are reset (step # 421), and the process proceeds to step # 413 to fix. The motor is turned off and the process ends.

It should be noted that the heating roller and the pressure roller in the standby state may be rotated by a very small rotation as long as the current pressure bonding portion is moved to another position. However, if the rotation force is made lower than the rotation at the time of fixing, the noise is further increased. It can be kept low.

By rotating the fixing roller pair several times under the condition that the pressure-bonding portion of the fixing roller pair moves to another position, the deformation tendency of the pressure-bonding portion on the surface of the roller can be smoothed to accelerate the recovery. ..

Further, in the above embodiment, the heat source is provided only to the heating roller which is one of the pair of fixing rollers, but the heat source may also be provided to the pressure roller.

[0062]

According to the present invention, the fixing roller is placed in a standby mode in which it is preheated to a predetermined temperature below the fixing temperature in a stationary state, so that the fixing roller can be quickly raised to the fixing temperature during use and wait. Fixing is possible without time, but each time a predetermined time elapses in the standby mode, the fixing roller is rotated by a predetermined amount so that the pressure-bonded portion of the fixing roller at this point moves to at least another part, and the fixing roller is preheated. In this state, before the local deformation of the crimping part is caused by pressure and preheating, the crimping part of the fixing roller moves to another, and the deformation at the previous crimping part can be recovered in an extremely short time. Along with
Since the deformation at the new crimping portion is only continued for the predetermined time or less, it is possible to recover in a shorter time with the movement of the crimping portion due to the rotation of the fixing roller during fixing. It is possible to avoid that the deformation of the pressure-bonded portion of the roller is left as it is and the roller is rotated to generate abnormal noise, and the conventional problem is solved. Moreover, since no special means for pressing and releasing the fixing roller is required, it does not cause a cost increase, and the fixing roller does not continue to be driven even when it is on standby. There is an advantage that the problem of life reduction due to noise, fatigue, friction, etc. does not occur if it is driven only for a limited short time.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment in which the present invention is applied to a copying machine.

FIG. 2 is a sectional view showing the fixing device of FIG.

3 is a block diagram of a control circuit of the device of FIG.

FIG. 4 is a main flowchart showing main operation control of the control circuit of FIG.

5 is a flowchart of a fixing motor control processing subroutine of FIG.

[Explanation of symbols]

 23 Fixing Device 41 Heat Source 42 Heating Roller 43 Pressure Roller 53 CPU 104 Main Switch

Claims (1)

[Claims] 1. A fixing device having a standby mode in which a heat source is provided in at least one of a pair of fixing rollers pressed against each other, and a standby mode in which the fixing roller preheats to a fixing temperature or lower is provided. A fixing device characterized in that, every time a predetermined time elapses in the mode, the fixing roller is rotated a predetermined time so that the pressure-bonding portion of the fixing roller at this point moves to at least another position.