JPH0980968A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent irregularities in an image caused by a temperature difference between the resist and counter-resist sides of a heating roller and damage to a fixing device cause by unnecessary idle running. SOLUTION: A controller for controlling the temp. of the heating roller of the fixing device through idle running compares the previous paper sheet with a paper sheet used this time, when commands to start a job are issued (step 81). When the pager is larger, the idle running for a previously set idle running time is executed with the number of copies at the previous time, elapsed time from the completion of the previous copying, etc., to prevent the irregularities in the image due to the temperature difference. When the paper at this time is smaller, the paper is not passed through a paper nonpassing area (temperature rising area) of the previous time, so that the idle running is not permitted. On the other hand, a control not to permit the idle running, even if the temperature difference vanishes by natural cooling due to the elapsed time from the previous time, is executed to prevent the damage to the fixing device due to the unnecessary idle running.

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 on recording paper used in an image recording device such as an electrophotographic copying machine, and more particularly to a fixing device using a heating roller.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 56-72 has a structure in which the set temperature of a heating roller is switched according to the size of recording paper.
It is disclosed in Japanese Patent Publication No. 470. Japanese Unexamined Patent Publication No. Sho 60-22164 discloses a technique in which a plurality of heaters corresponding to respective paper sizes are used to prevent an increase in temperature in a non-sheet passing area. The fixing roller has a predetermined temperature based on the information that the last transfer paper is discharged by the paper discharge detection means that detects the temperature of a plurality of different areas in the axial direction of the fixing roller and that detects the discharge of the transfer paper. The structure that rotates in the air for
It is disclosed in Japanese Patent Laid-Open No. 4-322284.

[0003]

A fixing device composed of a heating roller containing a heat source and a pressure roller press-contacted to the heating roller is designed to melt the toner on the surface of the heating roller.
The pressure roller is controlled and maintained at a temperature suitable for fixing, the pressure roller has an elastic layer on the surface, contacts the heat roller with a certain width, and the recording paper passes through this contact portion.
The toner was fixed on the paper by heat and pressure. By the way, in recent years, electrostatic recording devices such as copying machines have been increasing in speed, and the size of recording paper that can be copied has been diversifying. In order to meet the current demands, solutions such as increasing the temperature of the heating roller or increasing the pressure have been dealt with. However, if the heat distribution of the heating roller is set in accordance with the maximum size of the recording paper that can be copied, the recording paper will not be printed when the copying operation is continuously performed on recording paper of a small size such as B5 size paper. In the roller portion that does not pass, the roller temperature rises more than necessary, and there is a disadvantage that a hot offset phenomenon occurs. In addition, the paper may have wrinkles. Therefore, as disclosed in Japanese Unexamined Patent Publication No. 4-322284, when the temperature of the fixing device is uniformly adjusted by idling, if the size of the next paper to be used is smaller than that of the previous paper, Since the sheet does not pass through the non-sheet passing area of the preceding sheet, the image is not disturbed due to the temperature difference in the sheet, and the idle rotation time becomes a waiting time.

Further, the temperature rise in the non-sheet passing area which occurs when recording sheets are continuously copied, naturally cools with the lapse of time from the end of fixing. Therefore, if the cooling time of the fixing roller elapses from the end of copying and the next copy command is issued after the influence of the heat of the roller on the next copy disappears, idle rotation is not necessary. Generally, a fuser roll,
The pressure roll has a disadvantage that the separation claw and the temperature sensor are damaged by idle rotation over time and the life of the device is shortened. From this viewpoint, in this type of fixing device, idle rotation is desired to be as short as possible. Therefore, the present invention realizes a fixing device that effectively performs idle rotation of the fixing device to improve fixing defects, offsets, wrinkles, and the like, and can extend the life of the fixing device.

[0005]

A fixing device according to the present invention comprises a heating roller having a heater built therein, a pressure roller in pressure contact with the heating roller, a temperature detector for detecting the surface temperature of the heating roller, and n (n Is an integer) and a control device having a comparison circuit for comparing the (n + 1) th operation information with the (n + 1) th operation information,
When the (n + 1) th work start command is input, the paper used for the nth time is compared with the used paper for the (n + 1) th time, and if the (n + 1) th time used paper is large, the heating roller rotates idle. The basic configuration is to output the drive signal of. Further, the fixing device is a control device having an elapsed time counting means from the end of the nth (n is an integer) operation, a nth operation information storage means, and a comparison circuit of the nth and (n + 1) th operation information. And when the (n + 1) th operation start command is input, the comparison circuit outputs (n +
1) When it is determined that the sheet to be used for the first time is large, a configuration is provided in which a drive signal for idle rotation (control by drive time) preset based on operation information and information such as elapsed time is output.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of the fixing device shown in this embodiment,
2 is a perspective view, and FIG. 3 is an explanatory view of the heating roller. The fixing device includes a heating roller 10 and a pressure roller 20.
A heater 15 such as an infrared lamp is provided inside the heating roller 10.
Is arranged, and the pressure roller 20 is arranged in contact with the heating roller 10. The sheet 50 is guided by the upper guide 30 and the lower chute 35 and introduced between the heating roller 10 and the pressure roller 20, and the toner on the sheet 50 is fixed by heat and pressure while passing through the nip portion of both rollers. It The sheet 50 is peeled from the roller surface by the peeling claw 40, guided by the exit roller 60, and discharged.

The reference side of introducing the paper into the fixing device is the cash register side (the paper passing area regardless of the paper size), and the other side is the non-register side (the non-paper passing area depending on the paper size). Then, the temperature detection sensor for detecting the surface temperature of the heating roller 10 has at least the first temperature sensor 7 on the cash register side.
0, the second temperature sensor 75 is arranged on the side opposite to the cash register.
The surface temperature of the heating roller 10 of the fixing device is detected by the temperature sensors 70 and 75, and the surface temperature is adjusted by a control device (not shown).

Here, the register side of the fixing roll (paper passing area)
From the experience, it has been found that the image difference does not occur in the temperature difference between the non-register side (non-sheet passing area) and the non-sheet passing area temperature-paper passing area temperature (ΔT) ≦ 10 ° C. . After the previous copying operation, the fixing device is naturally cooled by being left unattended, and the temperature is lowered until there is no difference (ΔT) between the non-paper passing area temperature and the paper passing area temperature. But,
If the next copy operation is started before the difference (ΔT) between the non-paper passing area temperature and the paper passing area temperature drops to 10 ° C., the copy image is disturbed.

In view of this, the present invention has a structure in which the temperature difference between the paper passing area and the non-paper passing area of the heating roll is reduced to a temperature difference without image disturbance by idling the fixing device. A method for controlling the driving of the heating roll and the pressure roll in this fixing device will be described. Previously used copy paper width X
And the copy paper width Y used this time are compared, and when the paper used is X ≧ Y, the copy paper used this time does not pass through the non-paper passing area, so the temperature difference (ΔT) is 10 or more. When the difference is small, and when the temperature difference (ΔT) is larger than 10, both idle rotation is not performed. Also, the copy paper width X used last time
And the copy paper width Y used this time, when the paper Y used this time is large, there is no idle rotation when the temperature difference (ΔT) is less than 10, and when the temperature difference (ΔT) is greater than 10, It is configured to rotate idly (see FIG. 4). With this configuration, when the temperature of the fixing device does not need to drop due to idle rotation, for example, in the next copy operation, when the paper cannot pass through the non-sheet passing area where the temperature rises sharply due to the previous copy operation, etc. By not letting it spin idle,
This prevents damage to the fixing device due to idle rotation.

Next, a fixing device provided with a control device for executing more detailed control will be described. The fixing device is provided with a timer and is configured to count the time from the end of copying until the next copy start command is issued. here,
For each size, the number of copies, the temperature difference (ΔT) between the non-paper passing area temperature and the paper passing area temperature immediately after the end of copying, and the non-paper passing area temperature-
The time required for the paper passing zone temperature (ΔT) = 10 ° C. and the idle rotation time required for ΔT = 10 ° C. immediately after continuous copying were measured, and Table 2 shows the measurement results. According to this table, the temperature difference (ΔT) between the non-paper passing area and the paper passing area becomes 26 ° C., for example, when 20 sheets of A4 size paper are continuously copied, and this temperature difference (ΔT) becomes 10 ° C. It is necessary to stand for 120 seconds or spin for 40 seconds. Then, as the number of copies increases, the standing time and the idle rotation time increase. Further, in the case of B5 size paper, the temperature difference (ΔT) between the non-paper passing area and the paper passing area during continuous copying is higher than that of A4 size paper,
The time required for the temperature difference (ΔT) to reach 10 ° C,
Alternatively, it requires a long idle rotation time. And
Also in this case, the idle time and the idle rotation time increase as the number of copies increases from 60 to 99. Also, B
In the case of 4 size paper, as the number of copies increases, the leaving time or the idle rotation time required until the temperature difference (ΔT) reaches 10 ° C. becomes shorter than that of other size paper. . That is, in order to make the temperature difference (ΔT) between the non-paper passing area and the paper passing area 10 ° C. by idling,
It can be seen that in addition to the relationship between the copy paper used last time and the paper used this time, the number of copies made last time and the elapsed time from the end of the previous copy are involved. Here, from the experimental result of FIG.
When the size of the sheet used for the next copy is larger than the sheet width of the sheet used immediately before, the time idle rotation described in the table was executed depending on the number of copies immediately before and the elapsed time from the end of the previous copy. For example, when 60 sheets of B5 size were copied last time and then A4 size was copied, idle rotation was performed for 80 seconds. As a result, the difference (ΔT) between the non-paper passing area temperature and the paper passing area temperature was 10 ° C. or less, and the image was not disturbed.

Therefore, the fixing device of the present invention is
The difference (ΔT) between the non-sheet passing area temperature and the sheet passing area temperature in the (second) copy operation (job) based on the information such as the copy paper size and the number of continuous copies and the information about the elapsed time from the end of the previous copy. Is set to 10 ° C. or less, the idle rotation time is set from the idle rotation time shown in FIG. 5, and idle rotation is switched to idle rotation according to a predetermined matrix, or idle rotation is performed for a fixed time. By using such means, the difference (ΔT) between the non-paper passing area temperature of the heating roller and the paper passing area temperature in this (n + 1) th job is 10 ° C.
In the following, occurrence of image distortion and prevention of offset are performed.

That is, the fixing device of the present invention has the front (n)
The number of rotations of the idling rotation of the fixing device at the time of (n + 1) times of copying is determined by the information such as the number of copy modes (paper size, paper direction, number of copies) and the elapsed time from the end of the previous copy operation. It is set. An example of the matrix will be described with reference to FIG.

When the previous copy paper is A4 Paper insertion direction Vertical direction (1) When the previous number of copies is 20 or less When the elapsed time from the end of copy is 120 seconds or less. When the current paper is in the lateral direction of A3, B4, and A4, it is idly driven for 40 seconds. (2) When the previous number of copies is 21 to 60 When the elapsed time from the end of copying is 210 seconds or less. When the current paper is in the lateral direction of A3, B4, and A4, the idle rotation is performed for 70 seconds. (3) When the previous number of copies is 61 to 99 When the elapsed time from the end of copying is 360 seconds or less. When the current sheet is in the lateral direction of A3, B4, and A4, the idle rotation is performed for 90 seconds. If the paper is inserted in the horizontal direction, it will not idle.

In the same manner as described above, the corresponding condition is determined in advance depending on whether the paper of the previous job is B5 size, A4, B4 or A3 size (not shown). This matrix is basically because the paper size of the previous job is smaller than the size of the paper used this time, and when the elapsed time from the previous job is short, inconvenience occurs due to the temperature difference in the axial direction of the heating roller. Under these conditions, the temperature control is performed by idling. The control circuit of this control device will be described with reference to a block diagram (see FIG. 7). When a copy operation start command is input, when the CPU performs idle rotation in correspondence with a matrix based on information such as paper size, paper traveling direction, and number of continuous copies in the previous copy operation, and elapsed time up to the present time. Outputs an idle rotation control command for driving the main motor for a predetermined time.

Next, the control flow by the output from the CPU will be described with reference to the flow chart shown in FIG. Start at step 80, and copy button is turned on at step 81.
Then, in step 82, the previous paper width is compared with the paper width set this time. If the current paper size is smaller, the process proceeds to step 89 to start the copy operation. When it is determined in step 82 that the current paper size is large, the number of previous copies is determined in the next step.

When the previous number of copies is 20 or less, the routine proceeds to step 86, where the elapsed time from the end of the previous copy is
If the previous sheet is A4 size, it is 120 seconds, if it is B5 size in the vertical direction, it is 180 seconds, and if it is B4, it is 120 seconds, and the copy operation is started in step 89.
If the time has not elapsed, the process proceeds to step 90, and the set time A1 is idled. Then, after idling, the process proceeds to step 89 to start the copy operation.

If the previous number of copies is from 21 to 60, the routine proceeds to step 87, where it is determined whether or not the set time T2 seconds from the end of the previous copy has elapsed. For example, the set time is 210 seconds when the previous paper is A4 size, 300 seconds when it is B5 size vertical, and B4
The size is 210 seconds. If the set time has elapsed, the copy operation is started in step 89. If time has not elapsed, step 91
Proceed to step A2 and rotate the set time A2 idly. Then, after idling, the process proceeds to step 89 to start the copy operation.

When the previous number of copies is from 61 to 99, the routine proceeds to step 88, where it is determined whether the set time T3 seconds from the end of the previous copy has elapsed. For example, the set time is 360 seconds when the previous paper is A4 size, 480 seconds when it is B5 size vertical, and B4
The size is 330 seconds. If the set time has elapsed, the copy operation is started in step 89. Step 92 if time has not elapsed
Proceed to step S3 and rotate the set time A3 idly. Then, after idling, the process proceeds to step 89 to start the copy operation.

The idle rotation set time set in this fixing device will now be described with reference to the chart shown in FIG. For example, if the previous sheet was A4 portrait, this sheet is A
In the case of 3, B4 and A4 vertical directions, the set time A1 is 40 seconds, A2 is 70 seconds, and A3 is 90 seconds. Similarly, apply the current paper Y to the previous paper X, and
The set times for 1, A2 and A3 are determined.

As described above, when this fixing device executes the copy operation, the current idle rotation time is controlled by the previous copy operation information, so the temperature condition set by the minimum required idle rotation is set. It was possible to eliminate the waiting time due to unnecessary idle rotation. Also,
Even if the paper size of (n + 1) times is larger than the paper size of the previous n, the idle rotation is not performed if the next copy operation is requested after a certain time has elapsed from the end of the copy operation of the previous n. Can reduce the damage of heating roll and pressure roll due to idle rotation

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a fixing device.

FIG. 2 is a perspective view illustrating the operation of the fixing device.

FIG. 3 is a structural explanatory view of a heating roller.

FIG. 4 is a control chart according to paper size.

FIG. 5: Heat drop measurement value of the heating roller according to the paper size.

FIG. 6 is an example of a matrix.

FIG. 7 is a block diagram of a control device.

FIG. 8 is a control flowchart.

9 is a symbol explanatory chart of FIG. 8. FIG.

[Explanation of symbols]

10 heating roller, 15 heater, 20 pressure roller, 40 peeling claw, 50 paper, 70, 75 temperature detector.

Claims (4)

[Claims] 1. A heating roller having a built-in heater, a pressure roller in pressure contact with the heating roller, a temperature detector for detecting the surface temperature of the heating roller, and a drive signal for the heating roller based on a detection signal from the temperature detector. In a fixing device having a control device for outputting, the control device controls the operation information of the nth (n is an integer) and (n + 1)
When a (n + 1) th work start command is input, the paper used in the nth time is compared with the (n + 1) th used paper, and a (n + 1) th operation information is compared.
A fixing device configured to output an idle rotation drive signal to the heating roller when the paper used for the first time is large. 2. A heating roller having a built-in heater, a pressure roller in pressure contact with the heating roller, a temperature detector for detecting the surface temperature of the heating roller, and a drive command output by inputting a detection signal from the temperature detector. In the fixing device equipped with the control device, the fixing device has means for counting the elapsed time from the end of the n-th (n is an integer) operation, and the temperature detector measures the surface temperature on the registration side and the non-registration side of the heating roller. Upon detection, the control device stores the operation information storage means for the nth time, and
It has a comparison circuit with the (+1) th operation information, and (n + 1)
When the operation start command for the second time is input, and when the comparison circuit determines that the (n + 1) th used paper is large, the idle rotation drive preset from the temperature detection signal, the operation information, and the elapsed time information is driven. A fixing device configured to output a signal. 3. The fixing device according to claim 1, wherein the idling rotation drive signal output from the control device controls the drive time. 4. The idle rotation drive time output by the control device is set based on the rotation time at which the temperature difference between the register side and the counter register side does not affect the image. Or the fixing device described in 2.