JP2001125424A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which can control the temperature of a fixing device under control conditions suitable for itself without requiring any operator's hand irrelevantly to manufacture variance of a heat source and a fixing rotary body. SOLUTION: The image forming device is equipped with a couple of fixing rotary bodies having a heat source, a temperature sensor, and a control means which controls the heat source under specific control conditions; and the control means has a normal mode wherein a recording sheet while holding a toner image is passed through the press-contact part between the fixing rotary bodies and an adjustment mode wherein the recording sheet holding no toner image is passed through the press-contact part between the fixing rotary bodies and adjusts the control conditions according to the surface temperature of the fixing rotary bodies in the adjustment mode to control the heat source under the adjusted control conditions in the normal mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic method, such as a copying machine, a printer, a facsimile, and a multifunction peripheral thereof, and more particularly, to a temperature control technique of a fixing device of the image forming apparatus. Related.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a fixing device for fixing an unfixed toner image on a recording sheet such as a sheet or an OHP sheet by the action of heat and pressure is widely known. Such a fixing device generally includes a pair of fixing rotators that rotate while being pressed against each other, and includes a heat source such as a heater in the fixing rotator. In such a fixing device, it is necessary to keep the fixing temperature at an appropriate temperature in order to prevent hot offset, cold offset, and the like of the toner. Therefore, various techniques for controlling the temperature of the fixing device based on conventional control conditions have been proposed.

For example, in Japanese Patent Application Laid-Open No. 8-106234, in view of the problem that electric power supplied to a heater as a heat source fluctuates with a change in power supply voltage, an energization ratio of electric power supplied to the heater is controlled. Propose technology. In addition, the present applicant communicates with a first sensor provided in a non-area in order to accurately measure the temperature of the paper passing area while avoiding the inconvenience of contacting the temperature sensor with the paper passing area of the fixing rotator. A technique has already been proposed for measuring the temperature of the surface of the fixing rotator using a retractable second sensor provided in the paper area.

[0004]

However, as a result of further research, the present inventors have found the following problems. That is, manufacturing variations occur in the heat source such as a heater and the fixing rotating body for each individual, and individual differences occur in the calorific value and heat capacity thereof. Therefore, under the control conditions set on the premise of an average heat source and a fixing rotator, appropriate temperature control may not be performed in an individual image forming apparatus. In particular, recently, as the size of the image forming apparatus is reduced, the heat source and the fixing rotating body also tend to be reduced in size. Therefore, generally, the heat capacity of the heat source and the fixing rotating body is reduced, and the influence of the variation cannot be ignored. Exists.

On the other hand, it is possible for an operator to set control conditions one by one for each heat source and fixing rotator, but this not only requires human cost but also depends on the quality of the control conditions. It depends on the skill of the person and is not preferable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to be suitable for an individual image forming apparatus without depending on the production variation of a heat source or a fixing rotating body and without human intervention. It is an object of the present invention to provide an image forming apparatus capable of controlling the temperature of a fixing device under various control conditions.

[0007]

According to the present invention, a pair of fixing rotators having a heat source on at least one of them and rotating while being pressed against each other, a temperature sensor for measuring the surface temperature of the fixing rotator, A control unit for controlling the heat source under predetermined control conditions based on a measurement value of the temperature sensor, wherein the control unit includes the pair of fixing rotating members while holding the toner image on the recording sheet. A normal mode for passing the pressure contact portion of the fixing rotator, and an adjustment mode for passing the pressure contact portion of the pair of fixing rotators without holding the toner image on the recording sheet, based on the surface temperature of the fixing rotator in the adjustment mode. The control conditions are adjusted, and in the normal mode, the heat source is controlled under the adjusted control conditions (claim 1).

FIG. 1 illustrates the concept of the present invention. FIG. 1A shows the adjustment mode, and FIG. 1B shows the normal mode. In the figure, S indicates a recording sheet, and T in the figure indicates a toner image. By configuring the image forming apparatus in this manner, the control condition is adjusted based on the surface temperature of the fixing rotating body in the adjustment mode,
In the normal mode, since the heat source is controlled under the adjusted control condition, the temperature of the fixing device can be controlled under the control condition suitable for each image forming apparatus regardless of the manufacturing variation of the heat source and the fixing rotator. Further, since the adjustment of the control condition is automatically performed, no manual operation is required, and stable adjustment can be performed regardless of the skill level of the operator.

The present invention is based on the first aspect of the present invention, wherein the fixing rotator has, on its surface, a paper-passing area where a recording sheet can contact and a non-paper-passing area where it cannot contact. The temperature sensor includes a paper-passing area temperature sensor that is freely movable toward and away from the surface of the fixing rotating body and measures the surface temperature of the paper-passing area, and a non-paper-passing area that measures the surface temperature of the non-paper-passing area. A temperature sensor, wherein the control means abuts the sheet passing area temperature sensor against the surface of the fixing rotating body in the adjustment mode to measure the temperature thereof, and also controls the sheet passing area during sheet feeding in the normal mode. The temperature sensor is separated from the surface of the fixing rotator and the temperature of the surface of the fixing rotator is measured by the non-sheet passing area temperature sensor.

FIG. 2 illustrates the concept of the present invention. FIG. 2A shows the adjustment mode, and FIG. 2B shows the normal mode. In the figure, S indicates a recording sheet, and T in the figure indicates a toner image. Further, on the surface of each fixing rotator, there are a paper passing area L at the central portion in the axial direction, and two non-paper passing areas 1 at both ends in the axial direction so as to sandwich the paper passing area L. . When recording sheets of a plurality of sizes are used, the sheet passing area L is an area through which recording sheets of all sizes pass, and a non-sheet passing area l is an area through which recording sheets of any size do not pass. Respectively.

[0011] By configuring the image forming apparatus in this manner, in the adjustment mode, the sheet passing area temperature sensor is brought into contact with the surface of the fixing rotating body to measure the temperature. It is possible to control the temperature of the fixing device under a control condition suitable for each image forming apparatus irrespective of the heat source in the region and the manufacturing variation of the fixing rotating body. On the other hand, since the toner image is not held on the recording sheet in the adjustment mode, the paper passing area temperature sensor that is in contact with the fixing rotating body in the adjustment mode is contaminated by toner or stays in the paper passing area temperature sensor. There is no occurrence of the image defect caused by the spilled toner mass spilling on the fixing rotating body.

Further, even in the normal mode, the paper passing area temperature sensor is separated from the fixing rotating body surface and the temperature of the fixing rotating body surface is measured by the non-paper passing area temperature sensor. There is no contamination of the temperature sensor by toner and no image defects.

The control means adjusts the control conditions based on the surface temperature of the fixing rotator and / or controls the heat source, and adjusts the control conditions based on a temperature change rate of the surface temperature of the fixing rotator. And / or may control the heat source (claim 3). By configuring the image forming apparatus in this way, the control conditions can be more appropriately adjusted and the heat source can be controlled. Adjustment of these control conditions and control of the heat source may be performed by selecting from a plurality of stages or may be performed continuously.

The above control conditions are, for example, a duty ratio for energizing the heat source and / or a target value of the surface temperature of the fixing rotator. The temperature sensor may be configured to be detachable from the image forming apparatus. By configuring the image forming apparatus in this way, the image forming apparatus and the temperature adjusting jig having the temperature sensor are configured separately, and the temperature adjusting jig is attached to the image forming apparatus only in the adjustment mode. , Control conditions can be adjusted.

These image forming apparatuses are provided with a display unit for displaying a message to a user and a detachable fixing device, and the control means performs an adjustment mode on the display unit when the fixing device is detached. May be displayed.
With this configuration of the image forming apparatus, it is possible to urge the operator to execute the adjustment mode when the fixing device is attached or detached.

[0016]

First, a copier (image forming apparatus) according to the present embodiment will be described. FIG. 3 is a schematic configuration diagram of the copying machine. The copying machine 7 is of an electrophotographic type, and mainly includes an automatic document feeder provided so as to freely open and close a copying machine body 70 and a copy glass 72 installed on the upper surface of the copying machine body 70. And a device 71.

Inside the copier body 70, there is an image of a moving original conveyed onto the copy glass 72 by the automatic original conveying device 71 or an image of a fixed original placed on the copy glass 72 by opening the automatic original conveying device 62. A document reading unit 73 for reading a document and converting the image into an image signal; an image forming unit 74 for forming a visible image on a recording sheet based on the image signal received from the document reading unit 73;
And a sheet supply unit 75 for supplying a recording sheet to the recording medium.

The image forming section 74 is charged by a charging device (not shown), and is exposed to a laser beam modulated by an image signal from an exposure device 91.
0, a developing device 92 for visualizing or developing the electrostatic latent image formed on the photosensitive drum 90 by the exposure as a toner image developer, and feeding the developed image on the photosensitive drum 90 The fixing unit 1 includes a transfer unit 93 that transfers the image transferred to the recording sheet supplied from the unit 75 and a fixing device 1 that fixes the image transferred to the recording sheet to the recording sheet. The details of the configuration of the fixing device 1 will be omitted.

The paper feeding section 75 is provided at the lower portion of the copying machine main body 70, and is provided in a plurality (three in this embodiment) of paper feeding trays 80a to 80c and in each of the paper feeding trays 80a to 80c. Paper feeding mechanisms 81a to 81c. Each of the paper feed trays 80a to 80c is for stacking and storing recording sheets according to size or type. The paper feed trays 80a to 80c are detachably attached to the copying machine main body 70. Is sent out.

Each of the paper feed mechanisms 81a to 81c includes a paper feed tray 80.
Pickup rollers 81a-c which turn right to the recording sheet at the top of a-c and sequentially feed this recording sheet
The feed rollers 83a to 83c and the retard rollers 84a to 84c are a pair of rollers that receive the recording sheet sent out by the pickup rollers 82a to 82c and send out the recording sheet while preventing double feeding toward the image forming unit 74. It is configured. The pickup rollers 82a to 82c and the feed rollers 83a to 83c rotate by driving a motor (not shown), and the retard rollers 84a to 84c forming a pair with the feed rollers 83a to 83c include feed rollers 83a to 83c.
Follow the rotation of c.

A substantially S-shaped recording sheet transport path R is formed from each of the paper feed trays 80a to 80c to the image forming section 74. Further, on the upstream side of the recording sheet transport path R from the transfer unit 93 (on the side of the paper feed trays 80a to 80c),
A registration unit 8 that controls the timing of supplying the recording sheets sent from the paper feed trays 80a to 80c to the transfer unit 93
8 are provided. The resist section 88 is provided in the transfer section 9
3 and a pre-registration roller 88 provided upstream of the registration roller 88b in the recording sheet conveyance path to feed the recording sheet toward the registration roller 88b at a predetermined timing.
a.

On the other hand, there is provided a discharge roller 89 for sending the recording sheet on which an image has been formed by the image forming section 74 from the copying machine main body 70 to the outside. Further, on a transport path R from each of the paper feed trays 80 a to 80 c to the discharge roller 89, a pair of transport rolls 85 a to 85 c and 8
6, 87 are provided. The above is an outline of the entire copying machine 7 according to the present embodiment.

Next, the configuration of the fixing device 1 will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the fixing device 1 according to the present embodiment. The fixing device 1 includes a heating roll 11 (fixing rotating body) and a pressure roll 12 that rotate in directions indicated by arrows in the drawing while being pressed against each other, and further, inside the heating roll 11, a halogen lamp 10 (heat source) is provided. ). Then, the recording sheet on which the unfixed toner image has been formed is
, The unfixed toner image is fixed on the recording sheet by the action of heat and pressure at that time.

The heating roll 11 is made of an iron-based material having an outer diameter of 25 [mm] and a thickness of 0.2 [mm], and has a reduced thickness and reduced heat capacity. The surface has a thickness of several tens [μ
m] of Teflon. On the other hand, the pressure roll 12 has a surface coated with an elastic material made of silicon rubber, is disposed in pressure contact with the heating roll 11, and forms a nip portion N having a predetermined width with the heating roll 11. .

The following components are provided around the heating roll 11 and the pressure roll 12. A carry-in side guide plate 17 for guiding the insertion of the recording sheet is provided upstream of the nip portion N between the heating roll 11 and the pressure roll 12 in the conveyance direction of the recording sheet, and recording is performed on the downstream side also through the nip portion N. A discharge side guide plate 16 for guiding the sheet is provided. Further, the heating roll 1 downstream of the nip portion N
When the recording sheet is wound around and adheres to one surface, a peeling claw 15 is provided for peeling off the recording sheet. Further, paper discharge rolls 13 and 14 are provided downstream of the nip portion N to forcibly discharge the recording sheets inserted through the nip portion N.

The surface of the heating roll 11 is in contact with a first sensor 21 for measuring its temperature. Further, a retraction mechanism 41 for bringing the first sensor 21 into contact with and separating from the heating roll 11 is provided. The retract mechanism 41 includes an arm 411 supported by a fulcrum 412.
A cam 413 is provided between a spring 414 that fixes one end of the arm 411 by pulling it upward and a fulcrum 412 and one end of the arm 411 to which the spring 414 is fixed. The first sensor 21 is provided at the other end of the arm 411. When the cam 413 rotates, the arm 411 swings about the fulcrum 412, and the first sensor 21 attached to the tip of the arm 411 is rotated. Sensor 2
1 comes in contact with and separates from the heating roll 11. A third sensor 23 for measuring the temperature of the pressure roll 12 is in contact with the surface of the pressure roll 12. The second sensor and the fourth sensor contacting the heating roll 11 will be described later.

Next, a control system of the fixing device 1 will be described with reference to FIG. FIG. 5 is a block diagram illustrating a control system of the fixing device 1.

As a measuring means of this control system, a first sensor 21 (which can freely contact and separate) the surface temperature of the heating roll 11 in the sheet passing area, and one non-sheet passing sheet adjacent to the sheet passing area A second temperature sensor 22, which measures the surface temperature of the region,
A fourth temperature sensor 24 for measuring the surface temperature of the other non-sheet passing area existing adjacent to the sheet passing area, and a third sensor 23 for measuring the surface temperature of the sheet passing area of the pressure roll 12. I have. Further, when an instruction from the user is detected, the copier 7
User interface 51 for notifying the user of the state of the sheet, a conveyance sensor 5 for detecting the presence or absence of conveyance of the recording sheet
2 are provided.

The control unit 30, the retract control unit 31, the energization control unit 32, and the control unit for suitably operating the fixing device based on the measurement results, instructions, and detection results from these measurement units and the like. A motion control unit 33, an image formation control unit 34, and a transport control unit 35 are provided. here,
The retract control section 31 controls the contact and separation of the first sensor 21 by the retract mechanism 41. Energization control unit 3
2 controls the duty ratio of the halogen lamp 10 in the heating roll 11. The rotation control unit 33 controls the rotation of the heating roll 11 and the pressure roll 12 by the motor 43.
The image formation control unit 34 controls permission and prohibition of image formation. The conveyance control unit 35 controls the conveyance timing of the recording sheet.

The control unit 30 includes a CPU (Central Processing Unit) 300 and a memory 301, and controls these control units 31 to 35 as a whole. Also,
In the memory 301, measured values of the sensors 21 to 25, variables indicating the state of the copying machine 7, and various arithmetic expressions are stored.

FIG. 6 shows arithmetic expressions and arithmetic tables stored in the memory 301 of the control unit 30. Here, seven arithmetic expressions to and one arithmetic table are stored. The description of the arithmetic expressions and the arithmetic table will be made together with the description of the operation of the copying machine 7.

As described above, in this control system, each of the sensors 21 to 2
4, the retracting of the first sensor 21, the duty ratio of the halogen lamp in the heating roll 11, the rotation of the heating roll 11 and the pressing roll 12 based on the measurement result and the detection result from the user interface and the instruction from the user interface. By suitably controlling the movement, the presence or absence of image formation, and the timing of recording sheet conveyance, various effects can be achieved.

The operation of the copying machine 7 performed by the control system will be described below with reference to FIGS.

FIG. 7 is a flowchart for explaining the basic operation of the copying machine 7 performed by this control system. As shown in FIG.
Operation in the normal mode (S1) and operation in the adjustment mode (S1)
2) exists. Here, the operation in the normal mode is performed for the purpose of performing fixing at an appropriate fixing temperature based on the target value T2c of the measurement value by the second sensor 22 and the duty ratio Px for the halogen lamp 10. Then, the target value T2c and the duty ratio Px are determined based on a predetermined arithmetic expression shown in FIG. On the other hand, the operation in the adjustment mode is based on the target value T2c and the duty ratio P2.
This is performed for the purpose of adjusting a predetermined arithmetic expression for obtaining x according to the characteristics of the copying machine 7 and the fixing device 1.

When the adjustment mode is required (S3), for example, when the inspection is performed after the copying machine 7 is manufactured and before shipping, when the fixing device 1 is replaced after shipping, an explicit instruction from the operator is issued. Or the case of performing automatically is mentioned. When the adjustment mode is required, the control unit 30 may be configured to display the fact to the user via the user interface 51. Hereinafter, copying machine 7
Will be described in detail separately into the operation in the normal mode and the operation in the adjustment mode.

Normal Mode FIGS. 8 and 9 explain the detailed operation of the copying machine 7 in the normal mode (see S1 in FIG. 7) with reference to flowcharts (FIGS. 8 and S11 show S101 to S111).
9 to S122. FIG. 10 shows the first, second and third sensors 21, 22 and 2 in the normal mode.
3, measured values T1, T2, and T3, a copy instruction, a rotation instruction,
This indicates, over time, an energization instruction, an image formation instruction, a retract instruction, and temperature control by the first sensor or the second sensor.

At time 0, when copying is instructed from the user interface 51 such as a touch panel or a start button (S101), the control unit 30 sets the measured value T1 of the surface temperature of the heating roll 11 by the first sensor 21 at that time.
(= T1 ₀ ) and the measured value T3 (= T3 ₀ ) of the surface temperature of the pressure roll 12 by the third sensor 23 are detected and stored in the memory 301 (S102). The control unit 30, by the equation stored in the measurement value T1 _0, T3 ₀ and advance in the memory 301 These storage, computes the rotation start temperature D ₀ of the fixing device. Note that W ₁ to
W ₄ is a constant.

The control unit 30 calculates the temperature rise rate measurement start temperature T _{RS based} on the calculated rotation start temperature D ₀ of the fixing device and an equation stored in the memory 301 in advance. Rotation start temperature D ₀ and memory 301 in advance.
The temperature T _{RE at which the} temperature rise rate measurement ends is calculated by the equation stored in
Is calculated (S103). Further, the control unit 30 starts supplying power to the halogen lamp 10 at a duty ratio of 70% via the power supply control unit 31 (S104).

FIG. 11 explains the duty ratio of the electric power supplied to the halogen lamp 10. The duty ratio indicates a percentage of the number of AC waves actually applied to the halogen lamp 10 in a predetermined unit number of AC waves. For example, as shown in the figure, a duty ratio of 70% refers to a state in which power is applied to only 7 out of 10 alternating current waves and not applied to three.

Then, when the measured value of the surface temperature of the heating roll 11 by the first sensor 21 rises and reaches the temperature rise rate measurement start temperature T _RS calculated in S103, the control unit 30 starts the heating roll 11 The measured value T1 of the surface temperature of the first sensor 21 is the temperature rise rate measurement start temperature T _RS
, The time t from when the temperature rise rate measurement end temperature T _RE is reached is counted (S105 to S107). And the control unit 3
0 is the temperature rise rate T of the first sensor 21 according to the counted time t and the equation stored in the memory 301 in advance.
R1a is calculated (S108).

Further, the control unit 30 determines the temperature rise rate TR1a of the first sensor 21 portion calculated in S108,
01, the first, second, and fourth sensors 21, 22, and 24 calculated in the adjustment mode previously performed (see S2 in FIG. 7) and stored in the memory 301.
Temperature rise rate TR1k, TR2k, TR4k of each part
Thus, the predicted supply power PW is calculated (S109). Note that a, b, and C in the expressions are constants.

Then, the duty ratio Px after the rotation of the fixing device is started is selected based on the calculated predicted supply power PW and a table stored in the memory 301 in advance (S11).
0). For example, when the predicted supply power PW = 900,
Since 851 ≦ PW ≦ 950, a duty ratio of 80% is selected from the table.

Next, the measurement value T1 by the first sensor 21 of the surface temperature rises further the heating roll 11 reaches the fixing device pivoting start temperature D ₀ calculated in S103, the control unit 30, the rotary control A rotation command is issued to the motor 43 via the unit 33 to rotate the heating roll 11 and the pressure roll 12. Further, the control unit 30 issues a paper feed command through the conveyance control unit 35 issues a rotation command to a time t ₁ after a predetermined time (S112).

At the same time that the paper feed command is issued, the control unit 30
Sets the number-of-feeds counter in the control unit 30 to “1” (S113), measures the surface temperature of the heating roll 11 by the first sensor 21 measurement value T1 (= T1a (1)) and the second sensor 22 measurement. The value T2 (= T2a (1)) is stored in the memory 301 (S114). Then, the control unit 30 calculates these measured values T1a (1) and T2a (1) stored in the memory 301, the value “1” of the number-of-sheets-to-be-transmitted counter, and calculates the values in the adjustment mode previously performed. A target temperature T2c (1) of the second sensor 22 is calculated based on the stored correction coefficient Ry.

The control unit 30 controls the halogen lamp 10
% Power was supplied (see S104).
At the same time as the first sheet passing command, a command is issued to the power supply control unit 32, and the power supply rate is changed to the power supply rate Px selected in S110 (S116). And the first sensor 21 up to that point
Is switched from the temperature control by the second sensor 22 to the temperature control by the second sensor 22 (S117), and the control unit 30 issues a separation command to the contact mechanism 41 via the retract control unit 31. Then, the contact mechanism 41 separates the first sensor 21 from the surface of the heating roll 11.

The control unit 30 determines whether or not the second and subsequent recording sheets are continuously fed based on the signal from the conveyance sensor 52 (S119), and is continuously fed. In this case, the number-of-feeds counter in the control unit 30 is added (S120), and the measurement value T1 (= T1a (1)) of the first sensor 21 and the measurement value T2 of the second sensor 22 stored in the memory 301 are stored. (= T2a (1)), the value of the number-of-sheets-to-send counter “2”, the correction coefficient Ry calculated in the previously performed adjustment mode and stored in the memory 301
Then, the target temperature T2c (2) of the second sensor 22 is calculated (S121).
Update from 2c (1) to T2c (2) (S122).
At the same time, the second sheet of paper feed command is issued at time t _2.

Similarly, at time t ₃ , t ₄ ,..., T _n , the recording sheets are fed one by one, and accordingly, the target temperature T2c of the second sensor 22 is sequentially updated. The temperature of the heating roll 11 is controlled based on this (see FIG. 10).

On the other hand, if the second and subsequent recording sheets are not continuously fed, the control unit 30 determines whether or not to end copying (S123). The subsequent sheet feeding of the recording sheet is waited (S119). When ending, the control unit 30 issues a contact command to the contact mechanism 41 via the retract control unit 32. Then, the contact mechanism 41 causes the first sensor 21 to contact the surface of the heating roll 11 (S124). Furthermore, the second sensor 22
Is switched from temperature control by the first sensor 21 to temperature control by the first sensor 21 (S125), and the process is terminated (S126).

Adjustment Mode FIGS. 12 and 13 explain the detailed operation of the copying machine 7 in the adjustment mode (see S2 in FIG. 7) with reference to flowcharts (S201 to S211 correspond to FIGS.
FIG. 13 shows S212 to S221. Also, FIG.
Measurement values T1, T2, T3, T of the first, second, third, and fourth sensors 21, 22, 23, 24 in the adjustment mode.
4, a copy instruction, a rotation instruction, an energization instruction, an image formation instruction,
The retract instruction and the temperature control by the first sensor or the temperature control by the second sensor are shown over time.

At time 0, when an automatic temperature control adjustment (adjustment mode) of the fixing device 1 is instructed from the user interface 51 such as a touch panel or a start button, or when the copier 7 detects that the fixing device 1 has been replaced. Automatic temperature control adjustment is automatically performed (S201).
Is the first sensor 2 of the surface temperature of the heating roll 11 at that time.
And the measured value by 1 T1 (= T1 _0), measurement value measured by the third sensor 23 of the surface temperature of the pressure roll 12 T3 (= T
3 ₀ ) are stored in the memory 301 (S20).
2).

The control unit 30, by the equation stored in the measurement value T1 _0, T3 ₀ and advance in the memory 301 These storage, computes the rotation start temperature D ₀ of the fixing device. Further, the control unit 30, by the equation stored in advance in the memory 301 and the rotation start temperature D ₀ of the computed fixing device calculates the YutakaNoboru measurement start temperature T _RS, the rotation start of the computed fixing device A temperature rise rate end temperature T _RE is calculated from the temperature D ₀ and an equation stored in the memory 301 in advance (S203).

Next, the control unit 30 starts supplying power to the halogen lamp 10 via the power supply control unit 31 at a power supply rate of 70% (S204). Then, the control unit 30 determines the measured value T of the surface temperature of the heating roll 11 by the first sensor 21.
1, respectively counts the time t from the computed YutakaNoboru measurement start temperature T _RS to reach YutakaNoboru measurement termination temperature T _RE in S103 (S205 to S207). Then, the control unit 30 stores the counted time t and the memory 3 in advance.
The temperature increase rate TR1k of the first sensor 21 is calculated by the equation stored in the first sensor 21 (S208).

At the same time, the value T1 measured by the first sensor 21
Measured value T but according to the fourth sensor and the measurement value T2 (= T2 _RS) by the second sensor upon reaching YutakaNoboru measurement start temperature T _RS
4 (= T4 _RS ) is stored in the memory 301 and the first sensor 2
Storing measured values measured value T1 is according to the second sensor upon reaching YutakaNoboru measurement termination temperature T _RE by 1 T2 (= T2 _RE) and the measured value according to the fourth sensor T4 with (= T4 _RE) in the memory 301 . Then, the control unit 30 calculates the measured values T
2 _RS , T4 _RS , T2 _RE , T4 _RE , and the temperature rise rate TR2a of the second sensor 22 portion and the temperature rise rate TR4a of the fourth sensor 24 portion are respectively calculated by equations -2 and -4 stored in the memory 301 in advance. The calculation is performed (S208).

FIG. 15 is an enlarged view of a part of the temperature graph of FIG.
1, at time t from YutakaNoboru measurement start temperature T _RS to reach YutakaNoboru measurement termination temperature T _RE, the first, second, measured values according to the fourth each sensor 21, 22, 24 T1, T2 ,
It is a graph which shows the value of T4 with time.

The control unit 30 calculates the temperature rise rate TR1a of the first sensor 21 portion calculated in S108 in the previously performed normal mode, a formula stored in the memory 301 in advance, and calculated in S208 and stored in the memory 301. The predicted supply power PW is calculated based on the respective temperature rise rates TR1k, TR2k, TR4k of the first, second, and fourth sensors 21, 22, and 24 (S209). Then, the energization ratio Px after the start of rotation of the fixing device is selected based on the calculated predicted supply power PW and a table stored in the memory 301 in advance (S210).

[0056] Further surface temperature increases of the heating roll 11, the measurement value T1 by the first sensor 21 reaches the fixing device pivoting start temperature D ₀ calculated in S203, the control unit 30
Issues a rotation command to the motor 43 via the rotation control unit 33 to rotate the heating roll 11 and the pressure roll 12.
Further, the control unit 30 issues a paper feed command to a transport system (not shown) via the transport control unit 35 a predetermined time after issuing the rotation command. Further, at this time, the control unit 30 has issued an image formation prohibition command to an image forming system (not shown) via the image formation control unit 34 (S212).

At the same time as issuing a paper feed command, the control unit 30
Sets the number-of-feeds counter in the control unit 30 to "1" (S213), and measures the surface temperature of the heating roll 11 with the measurement value T1 (= T1k (1)) by the first sensor 21 and the measurement by the second sensor 22. The value T2 (= T2k (1)) is stored in the memory 301 (S214).

The control unit 30 controls the halogen lamp 10
% Power was supplied at the same time (see S204).
At the same time as feeding the first sheet, a command is issued to the power supply control unit 32, and the power supply rate is changed to the power supply rate Px selected in S210 (S215). Then, the first sensor 21 is connected to the heating roll 1
The temperature control (target temperature T1c = 180 [°]) by the first sensor 21 is continued while keeping the contact with No. 1 (S216).

The control unit 30 continues to feed blank recording sheets on which no image is formed one by one at times t ₁ , t ₂ ,... Until the ten recording sheets are fed. The number is counted by the transmission counter in the (S21)
7, S218). Then, when feeding the recording sheet Jumaime at time t ₁₀ (see FIG. 14), the heating roll 11
Of the surface temperature measured by the first sensor 21 (= T1)
k (10)) and the measurement value T2 (= T
2k (10)) are stored in the memory 301 (S219).

The control unit 30 updates the temperature control condition (S220). Here, the expressions are rewritten.
That is, the values of TR1k, TR2k, and TR4k in the equations are obtained from the values obtained in the previous adjustment mode, and the current adjustment mode (S20
Update to the value obtained in 8). Also, T1k in the equation
(1), T1k (10), T2k (1), T2k (1
0) is updated from the value obtained in the previous adjustment mode to the value obtained in the current adjustment mode (S214, S219). In addition,
Rewriting the correction coefficient Ry with the equation results in rewriting the equation. Then, the automatic temperature control mode ends (S221).

The operation of the copying machine 7 according to this embodiment has been described above.

FIG. 16 is a block diagram for explaining a control system of a copying machine 7 'according to a modification of this embodiment.
In this modification, connectors 24a and 24b are provided between the fourth sensor 24 and the control unit 30. By configuring the copying machine in this manner, the fourth sensor 24 is attached to the copying machine 7 'by fitting the connector 24a and the connector 24b into the copying machine 7' only in the adjustment mode (see S2 in FIG. 7). When the adjustment mode ends, the engagement between the copier-side connector 24a and the sensor-side connector 24b is released, and the fourth sensor 24 can be removed.

[0063]

As described above in detail, according to the present invention, fixing is performed under control conditions suitable for each image forming apparatus irrespective of manufacturing variations of a heat source and a fixing rotating body and without human intervention. An image forming apparatus capable of controlling the temperature of the apparatus can be provided.

[Brief description of the drawings]

FIG. 1 explains the concept of the invention according to claim 1;

FIG. 2 explains the concept of the invention according to claim 2;

FIG. 3 is a schematic diagram illustrating a copying machine according to an embodiment of the present invention.

FIG. 4 schematically illustrates a fixing device of a copying machine according to an embodiment of the present invention.

FIG. 5 is a block diagram illustrating a control system of the copying machine according to the embodiment of the present invention.

FIG. 6 shows an arithmetic expression and an arithmetic table stored in a memory of a control unit in advance.

FIG. 7 is a flowchart illustrating a basic operation of the copying machine according to the embodiment of the present invention.

FIG. 8 is a flowchart illustrating the operation of the copying machine according to the embodiment of the present invention in the normal mode.

FIG. 9 is a flowchart illustrating the operation of the copier according to the embodiment of the present invention in the normal mode.

FIG. 10 is a diagram for explaining a change in a measured temperature value in a normal mode of the copying machine according to the embodiment of the present invention and an operation of each control unit at that time.

FIG. 11 is a diagram for explaining the duty ratio.

FIG. 12 is a flowchart illustrating the operation of the copier according to the embodiment of the present invention in the adjustment mode.

FIG. 13 is a flowchart illustrating the operation of the copier according to the embodiment of the present invention in the adjustment mode.

FIG. 14 is a diagram for explaining a change in a measured temperature value in the adjustment mode of the copying machine according to the embodiment of the present invention and an operation of each control unit at that time.

FIG. 15 is a diagram for explaining in more detail the change of the measured temperature value in the adjustment mode of the copying machine according to the embodiment of the present invention.

FIG. 16 is a block diagram illustrating a control system of a copying machine according to a modification of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing device, 10 ... Halogen lamp, 11 ... Heating roll, 12 ... Pressure roll, 21 ... First sensor, 22 ... Second sensor, 23 ... Third sensor, 24 ... Fourth sensor, 30 ...
Control unit, 31 ... retract control unit, 32 ... energization control unit,
Reference numeral 33: rotation control unit, 34: image formation control unit, 35: transport control unit, 41: retract mechanism, 7: copying machine

Claims (4)

[Claims] At least one of the fixing rotators has a heat source and rotates while being pressed against each other, a temperature sensor for measuring a surface temperature of the fixing rotator, and a temperature sensor based on a measured value of the temperature sensor. A control unit for controlling the heat source under a predetermined control condition, the control unit comprising: a normal mode in which the toner image is held on a recording sheet and passes through a pressure contact portion of the pair of fixing rotators. And an adjustment mode for allowing the pair of fixing rotators to pass through the pressure-contact portion without holding the toner image on the recording sheet.The control condition is adjusted based on the surface temperature of the fixing rotator in the adjustment mode. In the mode, the heat source is controlled under the adjusted control conditions. 2. The fixing rotator has a sheet passing area where a recording sheet can contact and a non-sheet passing area where it cannot contact the surface of the fixing rotator. A sheet-passing area temperature sensor that is freely contactable and detachable and measures the surface temperature of the sheet-passing area; and a non-sheet-passing area temperature sensor that measures the surface temperature of the non-sheet-passing area. In the mode, the paper passing area temperature sensor is brought into contact with the surface of the fixing rotating body to measure the temperature thereof, and during the normal mode paper passing, the paper passing area temperature sensor is separated from the surface of the fixing rotating body, and 2. The image forming apparatus according to claim 1, wherein the temperature of the surface of the fixing rotator is measured by a non-sheet passing area temperature sensor. 3. The image forming apparatus according to claim 1, wherein the control unit adjusts the control condition and / or controls the heat source based on a temperature change rate of a surface temperature of the fixing rotator. 4. The image forming apparatus according to claim 1, wherein the temperature sensor is configured to be detachable from the image forming apparatus.