JP2000112188A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of obtaining a satisfactory image free of expansion and contraction by preventing a change in the speed of carrying of a transfer material which results from the expansion and contraction of the diameter of a pressure roller due to the heat of a heating means and an environmental temperature. SOLUTION: Based on information on the measurement of the passing time of a sheet material, measured by a laser diode 22 and pin-photodiode 23 in a sheet ejection part, a set condition for an operation at the time of image formation, for example the heating temperature of a heater of a heat fixing-body 15 by energization, is altered. Thus, a change in the speed of carrying of a sheet material which results from the expansion and contraction of the diameter of a pressure roller 16 due to the heat of the heater and an environmental temperature is prevented and a satisfactory image free of the expansion and contraction is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., utilizing an electrophotographic system.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile or the like using an electrophotographic system, the surface of an electrophotographic photosensitive member is uniformly charged by a charging device during image formation, and the charged electrophotographic photosensitive member is charged. The surface of the body is exposed by an exposure device to form an electrostatic latent image. Then, the electrostatic latent image is developed by a developing device to form a toner image, and the toner image is transferred to a transfer material such as paper by a transfer device, and the toner image is permanently fixed on the transfer material by a fixing device. Is heat-fixed and output.

Conventionally, a heat roller system has been generally used for fixing a toner image by the fixing device.
In order to save power and shorten the time from power-on to image output, a film heating and fixing device has been proposed (for example, Japanese Patent Application Laid-Open No. 63-313182, Japanese Patent Application Laid-Open No.
No. 1577878).

[0004] The film heating and fixing device comprises a heating element having a heating resistor such as a heater, a heat-resistant fixing film that slides in contact with the heating element on one side, and heats the transfer material through the fixing film. With a pressure roller to adhere to the body,
The toner image can be fixed as a permanently fixed image on the transfer material by heating the transfer material by nipping and transporting the fixing film and the transfer material together in the nip formed by the heating element and the pressure roller. .

[0005]

By the way, in the above-mentioned conventional film heating and fixing apparatus, the pressure roller expands and contracts due to heat generated by the heater and the surrounding environmental temperature. For example, when the amount of heat generated by the heater is large due to the fixing state of the toner image to the transfer material, the pressure roller expands and the diameter increases.
Therefore, the transfer distance of the transfer material per rotation due to the rotation of the pressure roller becomes longer, whereby the fixing film and the transfer material are conveyed together in the nip formed by the heating element and the pressure roller. The transfer speed of the transfer material increases.

For this reason, when the image forming apparatus provided with the film heat fixing device is a copying machine, the transfer speed of the transfer material is lower than the speed of forming the toner image on the electrophotographic photosensitive member in accordance with the read image data. There is a problem that the printed image becomes larger and the printed image formed as a result is elongated. Conversely, when the environmental temperature of the image forming apparatus is low, the opposite phenomenon occurs, and the image may shrink.

As described above, in the image forming apparatus provided with the above-mentioned film heating and fixing device, the phenomenon that the pressure roller expands and contracts by the heat of the heater and the surrounding environmental temperature, and the printed image expands and contracts by several millimeters in accordance with it. did. this is,
It was not a big problem when printing characters,
For example, printing a drawing such as an architectural drawing, a design drawing, or a mechanical drawing has become a serious problem.

Accordingly, the present invention is directed to an image forming apparatus capable of preventing a change in transfer material transport speed due to expansion and contraction of a diameter of a pressure roller due to heat generated by a heater and ambient temperature, thereby preventing expansion and contraction of a printed image. It is intended to provide a device.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a fixing means having a rotatable pressure roller and a heat fixing member which is in contact with the pressure roller and has a heating means. And transferring the transfer material on which the toner image formed on the image carrier is transferred between the pressure roller and the heat-fixing member, and thermally fixing the toner image on the transfer material to form an image. A measuring unit provided downstream of the fixing unit in the transfer material transport direction and measuring a passage time of the transfer material conveyed through the fixing unit, and an input from the measurement unit. And control means for changing operation setting conditions at the time of image formation based on the measured transfer material passage time measurement information.

[0010] The measuring means may be a pair of laser diodes that emit laser light and are disposed on opposite sides of the transfer material transport path, and a pin photodiode that receives the laser light.

Further, the heat-fixing member is provided with at least the heating means, and a contact member which slides in contact with the heating means on one surface and comes into contact with the transfer material having the toner image transferred to the surface on the other surface. A movable fixing film, and the operation setting condition is a heating temperature of the heating unit by energization.

Further, the heating and fixing member is a rotatable fixing roller provided with the heating means therein, and the operation setting condition is a heating temperature of the heating means by energization.

[0013] Further, there is provided exposure means for scanning the image carrier with a light beam in accordance with image information to form an electrostatic latent image. Scanning time.

In addition, there are provided an exposure means for forming an electrostatic latent image on the image carrier in accordance with the image information, and a magnification changing means for changing a magnification in the sub-scanning direction of the image information inputted to the exposure means. The operation setting condition is a scaling factor of the image information in the sub-scanning direction by the scaling means.

Further, there is provided a document reading means for reading image information of a document, and the operation setting condition is a document reading speed by the document reading means.

The image forming apparatus further includes a conveying unit for conveying the transfer material, and a driving unit for the conveying unit, wherein the operation setting condition is a driving speed of the driving unit.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a schematic configuration diagram showing an image forming section GK of an image forming apparatus according to the present embodiment (in the present embodiment, an electrophotographic facsimile machine FS). The facsimile apparatus FS includes, in addition to the image forming unit GK, an image reading unit that reads an image of a document, a storage unit that stores read image information, a communication control unit that exchanges information with an external device, and the like. It is provided with.

The facsimile apparatus FS of the present embodiment is
An upper cassette which is composed of an apparatus main body 1 and a sheet feeding unit 2 connected to a lower part of the apparatus main body 1 and is built in the apparatus main body 1 as sheet material supply means for supplying a sheet material to the image forming section GK. 3. A lower cassette 4 to be loaded into the paper feed unit 2 is provided. In the upper cassette 3 and the lower cassette 4, a plurality of sheet materials Sa and Sb of appropriate size and type are placed in a stacked state.

Further, on the side surface of the apparatus main body 1, the sheet material S placed on the upper cassette 3 and the lower cassette 4 is placed.
A small sheet material such as a postcard having a size different from a and Sb, or a sheet material that is not used frequently, such as an OHP sheet, can be appropriately placed by an observer and supplied to the image forming unit GK. Manual feed unit 5
Are provided, and the sheet material Sc is placed thereon. The upper cassette 3, the lower cassette 4, the manual paper feed unit 5, and the image forming unit GK are connected to the sub-transport paths Ha, Hb, H
c and the main transport path H1.

The sheet Sa from the upper cassette 3 is fed to the sub-transport path Ha by an upper sheet feeding solenoid for connecting a driving force to the meniscus roller 6 (corresponding to the upper sheet feeding solenoid in FIG. 3). ) To pull up the meniscal roller 6
Is rotated to separate and feed one sheet at a time. Similarly, the feeding of the sheet material Sb from the lower cassette 4 to the sub-transport path Hb is performed by rotating the meniscus roller 7, and the sheet material Sb is nipped by the pair of transport rollers 8 and transported along the sub-transport path Hb. Is done.

Further, the sheet material Sc from the manual paper feed unit 5
Is fed to the sub-transport path Hc by the pickup roller 9.
, The sheets are separated and fed one by one.

At the connection between the sub-transport routes Ha, Hb, Hc and the main transport route H1, the sub-transport routes Ha, Hb,
The registration rollers 10a and 10b for adjusting the timing of the sheet material to be conveyed Hc and the timing of the sheet material entering the image forming unit GK are arranged. Registration roller 10
b is in contact with the registration roller 10a, and rotates according to the rotation of the registration roller 10a.

On the upstream side of the main transport path H1, a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) 11 as an image carrier constituting the image forming portion GK, and a charging roller for charging the photosensitive drum 11 12. Exposure device (not shown) (corresponding to scanner unit 44 in FIG. 3), developing sleeve 1
Developing device (not shown), transfer roller (transfer section)
14 etc. are provided.

A fixing device 20 is provided downstream of the image forming section GK in the sheet conveying direction.
Has a heat fixing member 15 of a film heat fixing method, and a pressure roller 16 for abutting against the heat fixing member 15 to fix an unfixed toner image on a sheet material.

The image forming operation in the image forming section GK is performed as follows.

During image formation, the photosensitive drum 11 is driven to rotate at a predetermined process speed, and is uniformly charged by the charging roller 12 to which a charging bias has been applied. Then, the charged surface of the photosensitive drum 11 is exposed to laser light by an exposure device (the scanner unit 44 in FIG. 3) to form an electrostatic latent image corresponding to input image information. Then, the electrostatic latent image is developed by the developing sleeve 13 to which the developing bias is applied, and is visualized as a toner image.

When the toner image on the surface of the photosensitive drum 11 reaches the transfer nip between the transfer roller 14 and the photosensitive drum 11, the sheet material (for example, the sheet material Sa of the upper cassette 3) is removed at this timing. Transfer roller 14 conveyed to a transfer nip and applied with a transfer bias
The toner image is transferred. The sheet material to which the toner image has been transferred is conveyed to the fixing device 20, and the unfixed toner image is heated and pressed on the sheet material and fixed at the fixing nip between the heat fixing body 15 and the pressure roller 16.

Reference numeral 17 denotes a discharge roller pair for discharging the sheet material on which the toner image has been heated and fixed to the outside of the apparatus main body 1. Further, members denoted by reference numerals 18a to 18j in the drawing are conveyance guides.

The apparatus has a main motor (corresponding to the main motor 70 in FIG. 3) as driving means for the discharge roller pair 17 and the like. The driving force of the main motor 70 is controlled by the solenoids or clutches described above. When the sheet is pulled, the sheet is transmitted to the corresponding roller to feed and convey the sheet material.

Reference numeral 21 denotes a microswitch provided on the main transport path H1 immediately before the registration rollers 10a and 10b to detect a sheet material. In the present embodiment, the flag is tilted by the passage of the sheet material, and the switch is turned on / off. However, the present invention is not limited to this. For example, the proximity of the sheet material is detected by physically detecting the passage of the sheet material. It is also possible to employ a proximity switch or the like.

Reference numerals 22 and 23 denote a paper discharge portion laser diode for emitting laser light for detecting the passage time of the sheet material and a pin photodiode for receiving the laser light, respectively. Vs. 17
Is installed on the downstream side in the sheet material conveying direction. The sheet material passes between the paper discharge section laser diode 22 and the pin photodiode 23.

Although a mechanical switch and a general photo-interrupter composed of a light-emitting diode and a photodiode cannot accurately measure the passage time of paper with an accuracy of 1 mm or less, as in the present invention, the paper passage time is limited. By using the paper laser diode 22 and the pin photodiode 23, it is possible to measure a sheet material with high accuracy, for example, 0.5 mm or less.

FIG. 2 is a sectional view of the fixing device 20.

The sheet material S on which the toner image is formed in the image forming section GK which is conveyed along the main conveying path H1 (conveyed from the bottom to the top in the figure) is heated and fixed by the fixing member 15 and the pressing roller 16
And the unfixed toner T in the nip
a is heated and melted to form the fixing toner Tb.

The heat fixing member 15 is made of a polyimide having a thickness of several tens of microns and has a surface-treated heat-resistant film 3.
1. A head-shaped heater 32 having a small heat capacity as a heating means, film inner guides 33, 34, 35 for guiding the inside of the heat resistant film 31, and film inner guides 33,
A stay 36 for holding the heater 34 and a heater holding member 37 for holding the heater 32 are provided. The heat-resistant film 31
Lubricant such as heat-resistant grease is applied to the inside of the
2 and smooth sliding with the film inner guides 33, 34, 35.

According to the heat-fixing member 15, by energizing the head-shaped heater 32 having a small heat capacity, the nip between the heat-resistant film 31 and the pressure roller 16 is heated to a temperature at which the toner can be fixed in a short time. can do. Therefore, the starting time of the apparatus can be shortened, and in a state where the sheet material S is not being conveyed, the power supply is stopped to reduce power consumption. Further, a thermistor, which is a temperature detecting means (not shown), is attached to a portion of the heater holding member 37 facing the heater 32 to measure the temperature of the sheet passing area and the temperature of the non-sheet passing area of the sheet material S. The amount of current supplied to the heater 32 is controlled so as to reach the temperature.

FIG. 3 is a block diagram of the main components of the facsimile machine FS.

In FIG. 3, reference numeral 41 denotes sensors 1 and 14 for detecting various states of the image forming unit GK, transfer units (corresponding to the transfer roller 14 in FIG. 1) for performing transfer, and 14a.
Is a high voltage circuit for generating a high voltage required for transfer.

Numeral 17 denotes the above-mentioned microswitch, numeral 22 denotes a laser diode of the paper discharge section, and numeral 23 denotes a pin photodiode.

Reference numeral 44 denotes a scanner unit (exposure device) for scanning a laser, reference numeral 44a denotes a laser, and reference numeral 44b denotes a laser scanner motor, which rotates a polygon mirror (not shown) to scan the laser 44a. Reference numeral 44c denotes a scanner motor drive unit that drives the laser scanner motor 44b.

Reference numeral 44d denotes a mirror called a BD mirror for detecting that the laser 44a has been scanned and irradiated to a predetermined position, whereby the external connection device 81 described later knows the end of one printing line. The external connection device 81 transfers the data for one line to be printed next to the image forming unit GK as a synchronization signal.

Reference numeral 46 denotes an AC input section of an AC power supply. An AC power supply on / off switch 47 for the user to turn on and off the AC power supply and a device for converting the energy of the AC power supply to DC are provided downstream of the AC input section 46. A DC power supply 48 for operation is provided. Reference numeral 49 denotes a triac or the like, and the heater 32 of the heat-fixing body 15 of the fixing device 20.
Is a heater control unit that controls the AC voltage applied to the heater.

The heating and fixing member 15 has a heater 32 for performing heating and fixing, a thermistor A 50 for detecting the temperature of a sheet passing portion of the heater 32, and a sheet material S attached to an end face of the heater 32. Is provided with a thermistor B51 for detecting the temperature of a portion where the sheet material S does not pass when the width is small, that is, a so-called non-sheet passing portion. Also,
The pressure roller 16 has a thermistor C for detecting its temperature.
52 are provided.

Reference numeral 53 denotes a fan motor unit for lowering the temperature inside the apparatus, and reference numeral 54 denotes a fan motor drive unit for driving the fan motor unit 53.

Reference numeral 55 denotes a first control unit for controlling the entire image forming unit GK. The first control unit 55 controls the entire image forming unit GK and emits light from the above-described paper discharge unit laser diode 22. The passage time of the sheet material S is measured by inputting a signal from a pin photodiode (photo sensor) 23 that receives laser light, and the sheet material S by the heater 32 of the heat fixing member 15 is measured in accordance with the passage time of the sheet material S.
Is performed (details will be described later).

Reference numeral 56 denotes a cartridge section (not shown) to which a high voltage, which is dangerous when touched by a user, is applied;
This is a door switch unit for turning off the AC power supply 47 when the user opens a part where the heater 32, which is dangerous when touched by the user, is hidden by the heater 32, which is dangerous when touched by the user, to protect the user from danger. 57 is an AC power supply 47
Is an AC voltage detection circuit for detecting the voltage of the AC voltage.

Numeral 58 is constituted by a relay or the like.
Current interrupting means for interrupting the current under the control of the control unit 55;
Reference numerals 59, 60, 61, 62, and 63 denote driving circuits 1 to 5, each of which is configured by a transistor circuit or the like and controls supply of current to a solenoid, a clutch, or the like.

Reference numeral 64 denotes an upper paper feed solenoid for feeding the sheet material from the upper cassette 3, 65 denotes a lower paper feed clutch for feeding the sheet material from the lower cassette 4,
66 is a manual paper feeding solenoid for feeding the sheet material from the manual paper feeding unit 5, 67 is a lower paper feeding solenoid for feeding the sheet material from the lower cassette 4, and 68 is the registration rollers 10a and 10b. This is a registration clutch for rotating.

Reference numeral 69 denotes a current detecting means for detecting the total value of the current flowing through a plurality of solenoids or clutches and transmitting the detected value to the first control unit 55. Reference numeral 70 denotes a main motor that supplies a driving force to various driving rollers and the like that convey the sheet material, and reference numeral 71 denotes a driving circuit thereof.

Reference numeral 80 denotes an interface such as a serial interface, for example, for exchanging a command response signal from the image forming unit GK to the external connection device 81. The external connection device 81 is
An image forming unit G such as an image reading unit that reads an image of a document of the facsimile apparatus FS, a storage unit that stores the read image information, and a communication control unit that exchanges information with an external device.
This is a component of the facsimile machine FS other than K.

FIG. 4 shows the facsimile apparatus FS of FIG.
3 is a block diagram of the communication unit 100 of FIG.

The communication section 100 is connected to the image forming section GK via an interface (signal line) 80 and includes a second control section 101 for controlling each section in the block.

A second control unit 101 includes a document conveying motor 102, a document reading unit 103 for reading a transmission document and converting the same into image data, a network control unit (NCU) 104 for connecting a telephone line to a facsimile, and A modulation / demodulation device (modem) 105 for performing communication, an operation panel 106 for a user to instruct an operation command to each section of the device, a second sensor 107 for detecting a state of the facsimile device FS, and A drive system 108 including a reading motor for performing reading, a memory 109 for storing various data, a read image processing unit 110 for processing image data read by the document reading unit 103, a read image data Image data obtained by decoding the encoded image data that has been read, or the encoded image data A scaling unit 111 for scaling the image data obtained by decoding the image data stored in the memory, an encoder 112 for encoding the read image data, and re-encoding the received image data, The decoder 113 controls decoding of received image data and decoding of read and encoded image data.

The operation panel 106 is a facsimile machine F
An indicator 114 for displaying the state of S to the user;
A key (KEY) 115, which is an operation button for the user to instruct the facsimile machine FS to perform various operations, is provided.

The memory 109 includes an image memory 116 for storing received image data and the like, a system RAM (or a system memory) 117 which is backed up by a battery or the like even when a commercial power supply is cut off due to a power failure, and the data is not destroyed, and a facsimile machine FS. And a ROM 118 for determining specifications.

Next, the heating control of the sheet material S by the heating and fixing body 15 of the fixing device 20 in the present embodiment will be described with reference to a flowchart shown in FIG.

First, the paper discharge section passage time measurement routine is started under the control of the first control section 55, and the laser light emitted from the paper discharge section laser diode 22 is received by the pin photodiode 23, and the discharge roller pair 17 is received. The measurement of the passage time of the sheet material S passing through is started (steps S1, S2, S3). At this time, when the sheet material S passing through the discharge roller pair 17 passes through the discharge roller pair 17 and there is a sheet material S such as paper between the discharge portion laser diode 22 and the pin photodiode 23, the timer is started. (Steps S4 and S5).

When the sheet material (paper) S stops passing between the paper discharge section laser diode 22 and the pin photodiode 23, the timer is stopped (steps S6 and S7). If the passage time (timer value) of the sheet material (paper) S is within a predetermined time range, the heater 32 of the heat fixing member 15 is controlled normally to fix the toner image (step). S8, S9).

On the other hand, in step S8, the sheet material (paper) S
When the passing time (timer value) exceeds a predetermined time range, the voltage (applied energy) applied to the heater 32 of the heating / fixing body 15 is controlled to be lower than usual, thereby fixing the toner image. (Steps S10 and S1)
1).

In step S10, when the passage time (timer value) of the sheet material (paper) S is shorter than a predetermined time range, the voltage applied to the heater 32 of the heat fixing member 15 (normally) is increased. (The applied energy) is increased to fix the toner image (steps S12 and S12).
13).

In step S4, the sheet material (paper) S
When there is no sheet material, it is detected whether or not the sheet material (paper) S passes within a certain time (step S14), and when the sheet material (paper) S passes within a certain time (the sheet material (paper) within a certain time) ) If S is present), go from step S14 to step S4, and if the sheet material (paper) S does not pass within a predetermined time in step S14 (the sheet material (paper) S does not exist within a certain time) In this case, error processing is performed (step S15).

In step S6, if there is a sheet material (paper) S between the discharge portion laser diode 22 and the pin photodiode 23, it is determined whether the sheet material (paper) S passes within a predetermined time. If the sheet material (paper) S is detected (step S16) and the sheet material (paper) S has passed (if the sheet material (paper) S is exhausted within a predetermined time), the process proceeds from step S16 to step S6, and the sheet material is transmitted within a predetermined time at step S16. If the material (paper) S does not pass (if the sheet material (paper) S does not run out within a predetermined time), an error process is performed (step S17).

As described above, in the present embodiment, the passage time of the sheet material (paper) S discharged by the paper discharge section laser diode 22 and the pin photodiode 23 is measured, and the heater of the heat fixing member 15 is correspondingly measured. By changing the heating temperature of the heating roller 32, it is possible to suppress the diameter of the pressure roller 16 from being changed by the heat of the heater 32, prevent the sheet material conveying speed from increasing or decreasing, and obtain a good image without expansion and contraction. it can.

<Embodiment 2> This embodiment will also be described using the image forming apparatus shown in FIGS.

In the present embodiment, a laser scanner for performing scanning (scanning) with a laser 44a of an exposure device (scanner unit) 44 for exposing the photosensitive drum 11 with an image of a laser beam in order to prevent expansion and contraction of an image. The rotation drive of the motor 44b is controlled. Other configurations and image forming operations are the same as those in the first embodiment, and a description thereof will be omitted in the present embodiment.

Hereinafter, the control of the rotational drive of the laser scanner motor 44b in the present embodiment will be described with reference to the flowchart shown in FIG.

Steps S1 to S8 and steps S14 to S17 in FIG. 6 are the same as those in the first embodiment shown in FIG. In the present embodiment, in step S8, the sheet material (paper)
If the passage time of S (timer value) is within a predetermined time range, the laser scanner motor 44b of the exposure device (scanner unit) 44 performs normal rotation control to perform scanning (scanning) by the laser 44a. Perform (Step S20).

On the other hand, in step S8, the sheet material (paper) S
If the passing time (timer value) exceeds a predetermined fixed time range, scanning (scanning) by the laser 44a is performed by controlling the rotation speed of the laser scanner motor 44b to be lower than usual. Steps S10 and S21).

In step S10, if the passage time (timer value) of the sheet material (paper) S is shorter than a predetermined time range, control is performed so that the rotation speed of the laser scanner motor 44b is increased from the normal time. Then, scanning (scanning) by the laser 44a is performed (steps S12 and S22).

As described above, in the present embodiment, the passage time of the sheet material (paper) S discharged by the paper discharge section laser diode 22 and the pin photodiode 23 is measured, and the heater 32 is energized accordingly. When the first control unit 55 determines that the conveying speed of the sheet material (paper) S has increased due to the increase in the diameter of the pressure roller 16 due to the heat generated by the laser scanner motor 44 b of the exposure device (scanner unit) 44, When the rotation speed is increased, the heating of the heater 32 is stopped by stopping the power supply to the heater 32, and the environmental temperature is reduced, the diameter of the pressure roller 16 is reduced and the conveyance speed of the sheet material (paper) S is reduced. When the judgment is made at 55, the sheet material (paper) is controlled by lowering the rotation speed of the laser scanner motor 44b of the exposure device (scanner unit) 44. Conveyed speed by changing the printing speed to suit the good image free from expansion and contraction can be obtained.

<Embodiment 3> This embodiment is also described using the image forming apparatus shown in FIGS. 1 to 4 (in this embodiment, an electrophotographic facsimile machine FS).

In this embodiment, in order to prevent the image from expanding and contracting, the exposure device (scanner unit) 44 for exposing the photosensitive drum 11 to the image with a laser is scanned by the laser 44a (scanning). The magnification ratio in the sub-scanning direction of the image data to be processed is changed by a scaling unit (see FIG. 4) 111.
It was controlled by. Other configurations and image forming operations are the same as those in the first embodiment, and a description thereof will be omitted in the present embodiment.

Hereinafter, the control of the magnification of the received image data in the sub-scanning direction in the present embodiment will be described with reference to the flowchart shown in FIG.

Steps S1 to S8 and steps S14 to S17 in FIG. 7 are the same as those in the first embodiment shown in FIG. In the present embodiment, in step S8, the sheet material (paper)
If the passage time of S (timer value) is within a predetermined fixed time range, the scaling processing unit 111 controls the scaling of the image data at the normal scaling ratio, and records the image data at the normal scaling ratio. Exposure unit (scanner unit) for image forming unit GK
The scanning is performed by the laser 44a (scanning) (step S23).

On the other hand, in step S8, the sheet material (paper) S
If the passing time (timer value) exceeds the predetermined time range, the scaling processing unit 111 controls the magnification of the image data in the sub-scanning direction to be increased, and the image in the sub-scanning direction is controlled. The extended image data is sent to the exposure device (scanner unit) 44 of the image forming unit GK, which is a recording unit, and scanning (scanning) by the laser 44a is performed (step S24).

If the transit time (timer value) of the sheet material (paper) S is shorter than a predetermined time range in step S10, the scaling unit 111 changes the magnification of the image data in the sub-scanning direction. Is sent to the exposure device (scanner unit) 44 of the image forming unit GK, which is a recording unit, and scanning (scanning) is performed by the laser 44a (step). S12, S25).

FIGS. 8 and 9 are diagrams showing the flow of received image data in the image forming apparatus of the present embodiment (in the present embodiment, an electrophotographic facsimile apparatus FS).

As shown in both figures, the network control unit (NCU)
The received image data received from 104 through the modulation / demodulation device (modem) 105 is decoded by the decoder 113, re-encoded by the encoder 112, and stored in the memory 109. Then, the received image data stored in the memory 109 is decoded again by the decoder 113 and input to the scaling unit 111.

Then, as described above, the passage time of the sheet material (paper) S discharged by the discharge section laser diode 22 and the pin photodiode 23 is measured, and the sub-scanning of the received image data is performed accordingly. The magnification in the direction is changed by the magnification processing unit 111 and sent to the exposure device (scanner unit) 44 of the image forming unit GK, which is a recording unit, and the laser 44 a
Scanning (scanning).

As described above, in the present embodiment, the passage time of the sheet material (paper) S discharged by the paper discharge portion laser diode 22 and the pin photodiode 23 is measured, and the heater 32 is energized accordingly. When the first control unit 55 determines that the diameter of the pressure roller 16 has increased due to the heat generated by the first control unit 55 and the conveyance speed of the sheet material (paper) S has increased, the image data scaling unit 45 performs the sub-scanning direction of the image data. In addition, the first control is performed when the conveying speed of the sheet material (paper) S is reduced due to a decrease in the diameter of the pressure roller 16 due to a stop of heat generation due to a stop of energization of the heater 32 or a decrease in the environmental temperature due to a stop of energization to the heater 32. When the determination is made by the section 55, the image data scaling section 45 controls the image data scaling section 45 to increase the scaling ratio of the image data in the sub-scanning direction. By changing the down count, good images free from expansion and contraction can be obtained.

<Fourth Embodiment> This embodiment is an example in which the control operation of the third embodiment is applied to a copying machine (a copying machine that stores image data in a memory and forms an image). As shown, the document reading unit 103 and the read image processing unit 110
have.

In the present embodiment, as shown in FIG.
A document reading unit 103 reads image data of a document, and the read image data is subjected to predetermined image processing by a read image processing unit 110. The image data processed by the read image processing unit 110 is encoded by the encoder 112 and stored in the memory 109. Then, the same processing as in FIG. 9 is performed.

As described above, also in the present embodiment, the same effect as in the third embodiment can be obtained.

<Embodiment 5> This embodiment will also be described using the image forming apparatus shown in FIGS. The present embodiment is an example in which the image forming apparatus is applied to a copying machine (a copying machine that forms an image directly from input image data). As shown in FIG. 4, a document reading unit 103 and a read image processing unit 110.

In this embodiment, in order to prevent image expansion and contraction, when scanning (scanning) by the laser 44a of the exposure device (scanner unit) 44 for exposing the photosensitive drum 11 with a laser image, The reading speed of the document by the reading unit 103 is controlled. Other configurations and image forming operations are the same as those in the first embodiment, and a description thereof will be omitted in the present embodiment.

In the present embodiment, as shown in FIG.
The image data of the original is read by the original reading unit 103, and the read image data is subjected to predetermined image processing by the read image processing unit 110, and the image data processed by the read image processing unit 110 is input to the scaling unit 111.

Then, as described above, the passage time of the sheet material (paper) S discharged by the paper discharge section laser diode 22 and the pin photodiode 23 is measured, and the reading speed of the read image data is accordingly determined. The number of lines of print image data is changed in accordance with the change, and the number of lines of print image data is changed, and is sent to the exposure device (scanner unit) 44 of the image forming unit GK as a recording unit, and scanning (scanning) by the laser 44a is performed. I do.

Hereinafter, the control of the reading speed of the document in the present embodiment will be described with reference to the flowchart shown in FIG.

Steps S1 to S8 and steps S14 to S17 in FIG. 12 are the same as those in the first embodiment shown in FIG. In this embodiment, in step S8, if the passage time (timer value) of the sheet material (paper) S is within a predetermined time range, the document reading unit (see FIG. 4) 103
To read the image of the original at a normal reading speed, and send the image data to the exposure device (scanner unit) 44 of the image forming unit GK, which is a recording unit, at the normal reading speed, and perform scanning (scanning) by the laser 44a. Perform (Step S26).

On the other hand, in step S8, the sheet material (paper) S
If the passing time (timer value) exceeds the predetermined time range, the reading speed of the document is controlled to be reduced, and the read image data is exposed to the exposure device (the image forming unit GK). (Scanner unit) 44, and performs scanning (scanning) with the laser 44a (step S27).

In step S10, if the passage time (timer value) of the sheet material (paper) S is shorter than a predetermined time range, control is performed to increase the reading speed of the original, and the read image data is read. To the exposure device (scanner unit) 44 of the image forming unit GK, which is a recording unit,
Scanning (scanning) by the laser 44a is performed (steps S12 and S28).

As described above, in the present embodiment, the passage time of the sheet material (paper) S discharged by the paper discharge section laser diode 22 and the pin photodiode 23 is measured, and the heater 32 is energized accordingly. When the first control unit 55 determines that the diameter of the pressure roller 16 has increased due to the heat generated by the first control unit 55 and the transport speed of the sheet material (paper) S has increased, the reading speed of the document is increased, and When the generation of heat is stopped due to the stop of energization or the environmental temperature decreases, the pressure roller 16
When the first control unit 55 determines that the transport speed of the sheet material (paper) S has decreased due to a decrease in the diameter of the sheet material (paper) S, the transport of the sheet material (paper) S is controlled by reducing the reading speed of the document. By changing the number of lines of the print image data according to the speed, a good image without expansion and contraction can be obtained.

<Embodiment 6> This embodiment will also be described using the image forming apparatus shown in FIGS. 1 to 4 (in this embodiment, an electrophotographic facsimile apparatus FS).

In the present embodiment, in order to prevent expansion and contraction of an image, the rotational drive of the main motor (see FIG. 3) 70 for driving the discharge roller pair 17 and the like for conveying the sheet material S is controlled. Other configurations and image forming operations are the same as those in the first embodiment, and a description thereof will be omitted in the present embodiment.

Hereinafter, the rotation control of the main motor 70 in the present embodiment will be described with reference to the flowchart shown in FIG.

Steps S1 to S8 and steps S14 to S17 in FIG. 13 are the same as those in the first embodiment shown in FIG. In the present embodiment, when the passage time (timer value) of the sheet material (paper) S is within a predetermined fixed time range in step S8, the main motor 70 is controlled at a normal rotation speed, and the normal rotation speed is controlled. Sheet material (paper) S at transport speed
Is transported (step S29).

On the other hand, in step S8, the sheet material (paper) S
If the passage time (timer value) exceeds the predetermined time range, the rotation speed of the main motor 70 is controlled to be increased, and the sheet material (paper) S is transported at a transport speed higher than usual. (Steps S10 and S30).

In step S10, if the passage time (timer value) of the sheet material (paper) S is shorter than a predetermined time range, the rotation speed of the main motor 70 is controlled to be lower than normal. The sheet material (paper) S is transported at a low transport speed (steps S12 and S31).

As described above, in the present embodiment, the passage time of the sheet material (paper) S discharged by the paper discharge section laser diode 22 and the pin photodiode 23 is measured, and the heater 32 is energized accordingly. When the first control unit 55 determines that the diameter of the pressure roller 16 is increased due to the heat generated by the first control unit 55 and the transport speed of the sheet material (paper) S is increased, the transport speed of the sheet material (paper) S is reduced. , Heater 32
When the first controller 55 determines that the conveying speed of the sheet material (paper) S is reduced due to the stop of heat generation due to the stoppage of the power supply and the decrease in the environmental temperature, the conveying speed of the sheet material (paper) S is reduced. By controlling to increase the transport speed of (paper) S, a good image without expansion and contraction can be obtained.

[0101]

As described above, according to the present invention, the transit time of the transfer material input from the measuring means is measured, and the operation setting conditions (for example, the heating means of the fixing means, The heating temperature, the scanning time of the exposure unit on the image carrier, the magnification in the sub-scanning direction of the image information by the magnification unit, the original reading speed by the original reading unit,
By changing the driving speed of the driving unit that drives the transfer material conveying unit), it is possible to prevent the transfer material conveying speed from increasing or decreasing due to the expansion and contraction of the diameter of the pressure roller due to the heat of the heating unit and the environmental temperature, A good image without expansion and contraction can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view illustrating a fixing device of the image forming apparatus according to the present invention.

FIG. 3 is a block diagram of the image forming apparatus according to the present invention.

FIG. 4 is a block diagram of a communication unit of the image forming apparatus according to the present invention.

FIG. 5 is a flowchart of control according to the first embodiment of the present invention.

FIG. 6 is a flowchart of control according to the second embodiment of the present invention.

FIG. 7 is a flowchart of control according to Embodiment 3 of the present invention.

FIG. 8 is a diagram showing a flow of received image data according to the third embodiment of the present invention.

FIG. 9 is a diagram showing a flow of received image data according to the third embodiment of the present invention.

FIG. 10 is a diagram showing a flow of received image data according to the fourth embodiment of the present invention.

FIG. 11 is a diagram showing a flow of received image data according to the fifth embodiment of the present invention.

FIG. 12 is a control flowchart according to the fifth embodiment of the present invention.

FIG. 13 is a flowchart of control according to the sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed unit 3 Upper cassette 4 Lower cassette 5 Manual feed part 11 Photosensitive drum (image carrier) 12 Charging roller 13 Developing sleeve 14 Transfer roller 15 Heat fixing body 16 Pressure roller 17 Discharge roller pair 20 Fixing device (Fixing unit) 21 Micro switch 22 Paper discharge unit Laser diode (Laser diode) 23 Pin photodiode 31 Heat resistant film 32 Heater (Heating unit) 44 Scanner unit (Exposure unit) 55 First control unit (Control unit) 70 Main motor ( Driving unit) 103 Document reading unit (document reading unit) 111 Magnification processing unit (magnification unit)

Claims (8)

[Claims] An image forming apparatus comprising: a rotatable pressure roller; and a fixing unit having a heating and fixing unit in contact with the pressure roller and provided with a heating unit. The transfer unit transfers a toner image formed on an image carrier. An image forming apparatus that sandwiches and conveys a material between the pressure roller and the heat fixing member to thermally fix the toner image on the transfer material to form an image; Measuring means for measuring the transit time of the transfer material conveyed through the fixing means, provided at the downstream side of the fixing means, and performing image formation based on the transfer material transit time measurement information input from the measuring means. And control means for changing the operation setting conditions in the image forming apparatus. 2. The image according to claim 1, wherein the measuring unit includes a pair of laser diodes that emit a pair of laser beams, which are disposed on both sides of the transfer material conveyance path, and a pin photodiode that receives the laser beams. Forming equipment. 3. The heating and fixing member includes at least the heating unit, and a rotating unit that is in contact with the heating unit and is in contact with one surface of the heating unit, and is in contact with the transfer material having the toner image transferred to the surface of the other surface. The image forming apparatus according to claim 1, further comprising a movable fixing film, wherein the operation setting condition is a heating temperature of the heating unit by energization. 4. The image according to claim 1, wherein the heat fixing body is a rotatable fixing roller provided with the heating unit therein, and the operation setting condition is a heating temperature of the heating unit by energization. Forming equipment. 5. An image forming apparatus comprising: an exposure unit configured to scan the image carrier with a light beam in accordance with image information to form an electrostatic latent image; The image forming apparatus according to claim 1, wherein the scanning time is a scanning time. 6. An exposure means for forming an electrostatic latent image on the image carrier in accordance with image information, and a magnification changing means for changing a magnification in the sub-scanning direction of image information input to the exposure means. And
The image forming apparatus according to claim 1, wherein the operation setting condition is a magnification of the image information in the sub-scanning direction by the magnification unit. 7. The image forming apparatus according to claim 1, further comprising document reading means for reading image information of the document, wherein the operation setting condition is a document reading speed by the document reading means. 8. The image forming apparatus according to claim 1, further comprising a transport unit that transports the transfer material, and a driving unit of the transport unit, wherein the operation setting condition is a driving speed of the driving unit.