JP2002311730A - Image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem due to troubles such as lowering of throughput and lowering in print quality caused by generation of a difference between the carrying speeds of a carrying roller and a pressing roller and partially extending or reducing an image since both the carrying roller and the pressing roller are driven by one driving motor. SOLUTION: The driving source of a carrying means for carrying a recording paper sheet to a transfer position facing a photosensitive drum and the driving source of a heat resistant film, which is positioned between a heater and the recording paper sheet, to move while propagation heat from the heater to the recording paper sheet are respectively independently driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus such as a laser printer, and more particularly to an image recording apparatus using a heating means for fixing an image.

[0002]

2. Description of the Related Art FIG. 9 is a schematic diagram showing a conventional image recording apparatus. In FIG. 9, reference numeral 101 denotes a ceramic heater, 10
Reference numeral 2 denotes a thin heat-resistant film disposed outside the support member so that the support member can be moved by a guide. Reference numeral 103 denotes a pressing roller for pressing the film 102 against the ceramic heater 101. Is composed.

Reference numeral 105 denotes a transfer roller pressed against the photosensitive drum 112; 106, a transport roller for transporting a recording sheet;
Denotes a paper feed roller, 109 denotes a laser driver, and ON / OFF-modulates a semiconductor laser based on an image signal. The modulated image signal is horizontally scanned on a photosensitive drum 112 by a polygon mirror 110 rotated by a polygon motor 111. An electrostatic latent image is formed. 116 is a pressure roller 1
03, a motor for driving the transfer roller 105, the transport roller 106, and the paper feed roller 107;

Reference numeral 121 denotes a fixed mirror for scanning and exposing the laser beam reflected by the polygon mirror 110 onto the photosensitive drum 112, 122 denotes a charging roller for uniformly charging the surface of the photosensitive drum 112, and 123 denotes a charging roller formed on the surface of the photosensitive drum 112. A charging roller 122, a photosensitive drum 112, and a developing device 123 are integrally assembled in a case 124.
It is removable.

The above laser driver 109, polygon motor 111, polygon mirror 110, fixed mirror 211
Constitutes an optical system.

Next, the operation will be described.

The surface of the photosensitive drum 112 rotating in the direction of the arrow is uniformly charged by the charging roller 122. Image exposure is performed on the charged surface of the photosensitive drum 112 by an optical system to form an electrostatic latent image. This electrostatic latent image is developed when the photosensitive drum 112 rotates and passes through the position of the developing device 123, and is visualized by toner adhesion. On the other hand, the recording paper sent out by the paper feed roller 107 is conveyed to a transfer position where the photosensitive drum 112 and the transfer roller 105 come into contact with each other while being synchronized with the rotation of the photosensitive drum 112 by the conveyance roller 106, and the visualized image is formed. The transferred toner is transferred to recording paper. After the transfer, the recording paper is conveyed to a heat fixing device, where heat and pressure are applied by a ceramic heater 101 and a pressure roller 103, and the unfixed toner is heated and fixed on the recording paper, and then discharged outside the apparatus.

[0008]

However, in the above-mentioned conventional example, the pressing roller 103 is provided with the ceramic heater 101.
As a result, the sheet is heated through the heat-resistant film 102, and expands due to thermal expansion, resulting in an inconvenience that the conveyance speed of the recording paper changes. As a result, the transferred image on the recording paper in the transfer section is stretched, so that accurate printing cannot be performed, and the unfixed toner image protrudes from the recording paper, and the toner scatters in the apparatus at the time of transfer.

To avoid this problem, the pressure roller 10
The change in the paper transport speed due to the thermal expansion of
3, the control is performed to reduce the paper transport speed, and as shown by the bold line 200, the transport roller 10 is driven by one drive motor 116.
6 and the pressure roller 103 are driven, so that the throughput is reduced or the conveyance roller 106 and the pressure roller 103 are driven.
However, there is a problem that a difference occurs in the conveyance speed of the image, and the image is partially stretched or shrunk, resulting in a problem that the printing quality is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to prevent image expansion and contraction without lowering the throughput, to prevent the image from protruding from the recording paper, and to prevent the toner from scattering into the apparatus. The aim is to obtain a device.

[0011]

According to the present invention, there is provided an image recording apparatus having the following configuration.

(1) An optical system for scanning and exposing a laser beam corresponding to an image signal on a photosensitive drum, and a developing means for visualizing an electrostatic latent image formed on the photosensitive drum by the scanning exposure. Transport means for transporting the recording paper to a transfer position facing the photosensitive drum, a thin heat-resistant film, a heater for heating the recording paper pressed against the film, and a heater disposed opposite to the heater; An image recording apparatus including a fixing unit having a pressing member for pressing a recording surface of the recording paper together with the film, and a film moving unit; a driving source of the conveying unit; An image recording apparatus, wherein a driving source of the means is driven independently.

(2) In (1), either one of the transport speed of the transport unit or the moving speed of the film transport unit is made variable according to the number of images recorded on the recording paper. An image recording apparatus characterized by the above-mentioned.

(3) In (1), a temperature detecting means for detecting or estimating the temperature of the pressing member is provided,
An image recording apparatus, wherein either one of the transport speed of the transport unit and the moving speed of the film moving unit is variable according to the temperature detected by the temperature detecting unit.

(4) In (1), the rotation speed of the polygon scanner of the optical system for scanning and exposing the laser light is made variable according to the number of images recorded on the recording paper. Image recording device.

(5) In (1), there is provided a temperature detecting means for detecting or estimating the temperature of the pressing member,
An image recording apparatus, wherein a rotation speed of a polygon scanner of an optical system for scanning and exposing the laser beam is made variable in accordance with a temperature detected by the temperature detecting means.

(6) An image recording apparatus according to (1), wherein the reference clock of the image signal is variable according to the number of images recorded on the recording paper.

(7) In (1), there is provided a temperature detecting means for detecting or estimating the temperature of the pressing member,
An image recording apparatus, wherein a reference clock of the image signal is variable according to a temperature detected by the temperature detecting means.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a cross-sectional view of an image recording apparatus showing a first embodiment of the present invention, and FIG. 2 is a control block diagram. In FIG. 1, 1 is a ceramic heater disposed and fixed on a surface of a support member (not shown), 2 is a thin heat-resistant film disposed outside the support member so that the support member can be moved by a guide, Reference numeral 3 denotes a pressure roller for pressing the film 2 against the ceramic heater 1, and these constitute a heat fixing device. Reference numeral 4 denotes a motor for driving the pressure roller 3.

Reference numeral 5 denotes a transfer roller pressed against the photosensitive drum 12, reference numeral 6 denotes a conveyance roller for conveying a recording sheet, reference numeral 7 denotes a paper supply roller, and reference numeral 8 denotes a motor for driving the transfer roller 5, the conveyance roller 6, and the paper supply roller 7. . Reference numeral 9 denotes a laser driver which modulates the semiconductor laser based on the image signal with 0N / 0FF, horizontally scans the modulated image signal with a polygon mirror 10 rotated by a polygon motor 11, and forms an electrostatic latent image on a photosensitive drum 12. These form an optical system.

A fixed mirror 21 scans and exposes the laser beam reflected by the polygon mirror 10 onto the photosensitive drum 12;
Reference numeral 2 denotes a charging roller for uniformly charging the surface of the photosensitive drum 12, and reference numeral 23 denotes a developing device for visualizing an electrostatic latent image formed on the surface of the photosensitive drum 12, and includes a charging roller 22, the photosensitive drum 12, and The developing device 23 is integrated with the case 24 and is detachable from the device main body 25.

The image recording apparatus according to the present invention has the above-mentioned structure, and is different from the conventional image forming apparatus shown in FIG. 9 in that a motor 4 for driving a pressure roller 3, a transfer roller 5, a transport roller 6, and a paper feed roller. The difference is that a motor 6 for driving the motor 7 is provided separately and independently, and the other configuration and the operation of forming an image on recording paper are the same.

FIG. 2 shows a control block for controlling the image recording apparatus of the present invention. In FIG. 2, reference numeral 14 denotes an image controller, which performs image development based on code data from a host computer (not shown). A reference clock (VDOCL) (not shown) that oscillates at a reference frequency for on / off modulating a laser beam scanned in the main scanning direction at a predetermined resolution.
K), and generates an image (VDO) signal. An engine controller 13 controls all control of the image recording apparatus.
Reference numeral a denotes print number counting means provided in the engine controller 13.

The pressure roller 3, which is a component of the above-mentioned heat fixing device, is a ceramic heater 1 when performing continuous printing.
From the outside, causing thermal expansion and increasing the outer diameter. The relationship between the number of prints and the amount of change in outer diameter is as shown in FIG. After the leading edge of the recording paper reaches the pressure roller 3 due to an increase in the outer diameter of the pressure roller 3, the paper conveyance speed is increased, so that the transferred image on the recording paper is elongated. In some cases, the image protrudes and toner is scattered in the apparatus during transfer.

To prevent this state, when the engine controller 13 detects that continuous printing has been performed by the print number counting means 13a, the engine controller 13 predicts the expansion rate of the pressure roller according to the number of prints, and moves the film 2. The rotation speed of the dedicated motor 4 as a means is reduced. For example, when the motor 4 is a stepping motor, as shown in FIG. 4, the excitation pulse frequency is reduced in accordance with the number of prints, thereby keeping the recording paper transport speed constant and preventing the transfer image from growing.

(Second Embodiment) FIG. 5 is a control block diagram showing a second embodiment of the present invention. In FIG.
Is a temperature detecting means for detecting the temperature of the pressure roller 3,
The other configuration is the same as the control block of the first embodiment shown in FIG. However, the engine controller 13 does not have the print number counting means 13a.

FIG. 6 shows the relationship between the temperature of the pressure roller 3 and the amount of change in the expansion coefficient. In the second embodiment, the engine controller 13 detects the temperature as in the first embodiment. According to the temperature of the pressure roller 3 detected by the means 15, the expansion rate of the pressure roller 3 is predicted, the rotation speed of the motor 4 is reduced, and the excitation pulse frequency is reduced according to the temperature rise. Keep the recording paper transport speed constant,
The image can be prevented from being stretched.

(Third Embodiment) FIG. 7 is a control block diagram showing a third embodiment of the present invention. FIG. 7 is different from FIG. 2 except that it is specified that the polygon motor 11 is controlled by the engine controller 13. It has the same configuration as the control block of the first embodiment shown. In the third embodiment, when the pressure roller 3 thermally expands, the rotation speed of the motor 4 is fixed, and the motor for driving the transfer roller 5, the transport roller 6, and the paper feed roller 7, as shown in FIG. The number of rotations of 8 is increased. By doing so, expansion and contraction of the image can be prevented without lowering the transport speed.

At this time, as the transport speed increases, the period of the vertical synchronization signal (not shown) determined by the rotation speed of the polygon mirror 10 needs to be increased in the same manner as the transport speed increase rate. That is, the rotation speed of the polygon motor 11 that rotates the polygon mirror 10 is increased. The means for finely adjusting the number of rotations can be realized by, for example, using a means for modulating the reference clock (VDOCLK) of the image signal by a PLL oscillator or changing the count value of the speed discriminator. is there.

At the same time, as the scanning speed of the laser 9 on the photosensitive drum 12 increases due to the increase in the rotation speed of the polygon mirror 10, it goes without saying that the reference clock frequency of the image signal also needs to be modulated and increased. .

As described in the second embodiment of the present invention, it is also possible to detect the expansion rate of the pressure roller 3 based on the temperature detected by the temperature detecting means 15 and to modulate the transport speed. That is clear.

[0033]

As described above, according to the present invention, an optical system for scanning and exposing a laser beam corresponding to an image signal on a photosensitive drum, and an electrostatic latent image formed on the photosensitive drum by the scanning exposure are provided. Developing means for visualizing the image; conveying means for conveying the recording paper to a transfer position facing the photosensitive drum; a thin heat-resistant film and a heater for heating the recording paper pressed against the film; An image recording apparatus comprising: a fixing unit having a pressing member disposed to face a heater and pressing the recording surface of the recording paper against the heater together with the film; and a film moving unit for moving the film. In this case, since the drive source of the transport unit and the drive source of the film are driven independently, a change in the paper transport speed due to thermal expansion of the pressure roller is detected, and the transport roller B The speed of the roller, the transfer roller, the photosensitive drum or the speed of the pressure roller is variable, the rotation of the polygon scanner is variable, and the reference clock of the image signal is variable, so that the image expansion and contraction can be performed without lowering the sleep. There is an effect that an image recording apparatus can be obtained which prevents the toner from spilling out of the recording paper and scattering the toner inside the apparatus.

According to the present invention, either the transport speed of the recording paper transport unit or the moving speed of the film transport unit is made variable depending on the number of images recorded on the recording paper. There is an effect that it is possible to prevent the image from expanding and contracting without dropping the sleep, to protrude from the recording paper, and to more reliably prevent the toner from scattering in the apparatus.

According to the present invention, there is provided a temperature detecting means for detecting or estimating the temperature of the pressing member, and the conveying speed of the recording paper conveying means or the conveying speed of the recording paper conveying means depending on the temperature detected by the temperature detecting means. Since either one of the moving speeds of the film moving means is configured to be variable, it is possible to prevent image expansion and contraction without dropping the sleep, to protrude from the recording paper, and to more reliably prevent toner scattering in the machine. There is an effect that can be.

According to the present invention, the rotation speed of the polygon scanner of the optical system that scans the laser beam is made variable according to the number of images recorded on the recording paper. , Prevent image expansion and contraction,
There is an effect that the toner can be more reliably prevented from protruding from the recording paper and scattering inside the apparatus.

According to the present invention, there is provided a temperature detecting means for detecting or estimating the temperature of the pressing member. Therefore, it is possible to prevent the image from expanding and shrinking, dropping out of the recording paper, and more reliably preventing the toner from scattering in the apparatus without dropping the sleep.

According to the present invention, since the reference clock of the image signal is made variable in accordance with the number of images recorded on the recording paper, it is possible to prevent expansion and contraction of the image without lowering the sleep time. There is an effect that the toner can be more reliably prevented from protruding from the recording paper and scattering inside the apparatus.

According to the present invention, a temperature detecting means for detecting or estimating the temperature of the pressing member is provided, and the reference clock of the image signal is made variable in accordance with the detected temperature of the temperature detecting means. Therefore, there is an effect that the expansion and contraction of the image can be prevented, the toner does not protrude from the recording paper, and the scattering of the toner in the apparatus can be more reliably prevented without lowering the sleep.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image recording apparatus according to a first embodiment.

FIG. 2 is a control block diagram showing a first embodiment.

FIG. 3 is a diagram showing the relationship between the number of prints and the expansion coefficient of a pressure roller.

FIG. 4 is a diagram showing speed control of the motor according to the first embodiment;

FIG. 5 is a control block diagram showing a second embodiment.

FIG. 6 is a diagram showing the relationship between the temperature of the pressure roller and the expansion coefficient.

FIG. 7 is a control block diagram showing a third embodiment.

FIG. 8 is a diagram illustrating speed control of a motor according to a third embodiment.

FIG. 9 is a sectional view showing a conventional heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic heater 2 Thin film 3 Pressure roller 4 Motor 5 Transfer roller 6 Conveying roller 7 Feeding roller 8 Motor 9 Laser driver 10 Polygon mirror 11 Polygon motor 12 Photosensitive drum 13 Engine controller 14 Image controller 15 Temperature detecting means 16 Motor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA12 DA46 ED04 ED16 ED25 ED30 EE02 EE03 EE04 EF09 ZA07 2H033 BA11 BA32 BE03 CA07 CA19 CA36 CA40 2H071 CA01 DA12 DA21 DA27 2H072 AB20 CA01 CB08 JA02 JA08 2H076 AB

Claims (7)

[Claims] An optical system for scanning and exposing a laser beam corresponding to an image signal on a photosensitive drum, a developing unit for visualizing an electrostatic latent image formed on the photosensitive drum by the scanning exposure, and Conveying means for conveying the recording paper to a transfer position facing the photosensitive drum, a thin heat-resistant film, a heater for heating the recording paper pressed against the film, and a heater disposed opposite to the heater; A fixing unit having a pressing member for pressing the recording surface of the recording paper together with the film, and a film moving unit for moving the film, wherein a driving source of the conveying unit; An image recording apparatus wherein a driving source of a film moving means is driven independently. 2. A transport speed of the transport unit according to claim 1, wherein the transport speed is determined according to the number of images recorded on the recording paper.
An image recording apparatus, wherein either one of the moving speeds of the film moving means is variable. 3. The apparatus according to claim 1, further comprising a temperature detecting means for detecting or estimating the temperature of the pressurizing member, and a conveying speed of the conveying means or a conveying speed of the conveying means according to a temperature detected by the temperature detecting means. An image recording apparatus, wherein either one of the moving speeds of the film moving means is variable. 4. An image according to claim 1, wherein a rotation speed of a polygon scanner of an optical system for scanning and exposing the laser beam is variable according to the number of images recorded on the recording paper. Recording device. 5. The apparatus according to claim 1, further comprising a temperature detecting unit for detecting or estimating the temperature of the pressing member, wherein the rotation speed of a polygon scanner of an optical system that scans and exposes the laser beam is set to the rotation speed. An image recording apparatus, wherein the image recording apparatus is variable according to a temperature detected by a temperature detecting means. 6. The image recording apparatus according to claim 1, wherein a reference clock of the image signal is variable in accordance with the number of recorded images on the recording paper. 7. The apparatus according to claim 1, further comprising a temperature detecting means for detecting or estimating the temperature of the pressurizing member, wherein a reference clock of the image signal is set according to a temperature detected by the temperature detecting means. An image recording apparatus characterized by being variable.