KR100465322B1 - Fusing apparatus for laser printer - Google Patents

Abstract

A fixing apparatus of a laser printer for pressing a printing paper having passed through a developing unit and fixing a toner image on the printing paper, comprising: a frame; A heating roller rotatably installed in the frame and having a heater installed therein; A pressure roller installed on the frame to be in contact with the heating roller, the pressure roller pressing the printing paper passing between the heating rollers; A pressurizing unit for pressing the pressurizing roller elastically to the heating roller side; And a pressing force adjusting means for automatically adjusting the pressing unit to adjust the pressing force of the pressing roller against the heating roller according to the type of the printing paper input.

Description

Fusing apparatus for laser printer

The present invention relates to a fixing apparatus of a laser printer.

In general, a laser printer scans a laser light from a laser scanning device onto a photosensitive medium such as a photosensitive drum to form an electrostatic latent image corresponding to a desired image on the medium. In the electrostatic latent image area, a toner as a developer is supplied by a developing means such as a developing roller to develop a visible image. The visible image of the toner formed on the photosensitive medium is transferred to printing paper passing between the photosensitive medium and the transfer medium. The printing paper passes through the fixing unit with the visible image transferred. In the fixing apparatus, the printing paper passing through is fixed at a high temperature / high pressure, whereby a visible image on the printing paper is instantaneously fixed and filmed on the printing paper. In this way, the printing paper via the fixing device is discharged to the outside of the printer main body to finish printing.

The fixing apparatus includes a heating roller having a heater therein, and a pressure roller configured to press the heating roller to a predetermined pressure while rotating in contact with the heating roller. The pressure roller is elastically biased toward the heating roller by a predetermined elastic means.

On the other hand, the fixing device is set so that the heating roller and the pressure roller are in contact with a suitable pressure so as to be suitable for a printed material of the same thickness as A4 paper which is a printing paper which is commonly used. Therefore, when printing on a thicker paper, for example, an envelope, than the normal paper, there is a problem that the envelope is wrinkled or wrinkled while passing through the fixing device.

To this end, when printing the envelope, a separate means for adjusting the pressing force of the pressing roller against the heating roller should be provided. Even in this case, the user must open a partial cover of the printer and manually operate the envelope every time the envelope is printed. After that, there is a hassle such as having to manually revert back.

The present invention has been made to solve the above problems, an object of the present invention is to provide a fixing apparatus of a laser printer having an improved structure to automatically adjust the pressing force of the pressing roller against the heating roller.

1 is a schematic cross-sectional view showing a fixing device of a laser printer according to an embodiment of the present invention.

Figure 2 is a schematic cross-sectional view showing an operating state when printing the envelope in the fixing apparatus shown in FIG.

3 is a flow chart showing a printing operation using the fixing device according to an embodiment of the present invention.

Figure 4 is a schematic cross-sectional view showing a fixing device of a laser printer according to another embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

10.Frame 11.Heating Roller

13. Pressure roller 15. Pressure unit

16. Pressure lever 17. Pressure member

20. Driving part 21. Rotary lever

23. Solenoid 25. Control part

31.Worm wheel 33.Worm

35..Motor

A fixing apparatus of a laser printer according to the present invention for achieving the above object comprises: a fixing apparatus of a laser printer for fixing a toner image on the printing paper by pressing the printing paper passing through the developing unit; A heating roller rotatably installed in the frame and having a heater installed therein; A pressure roller installed on the frame to be in contact rotation with the heating roller, and pressurizing the printing paper passing between the heating rollers; A pressurizing unit for elastically pressing the pressurizing roller toward the heating roller; And pressing force adjusting means for automatically adjusting the pressing unit to adjust the pressing force of the pressing roller against the heating roller according to the type of printing paper input.

Here, the pressing unit, one end is rotatably installed in the frame, the pressing lever in contact with the shaft of the pressing roller; It is preferable to include; a pressure spring is installed on the frame to press the pressure lever toward the pressure roller side so that the pressing force is transmitted to the heating roller side.

In addition, the pressing force adjusting means, the rotation lever to push the pressing unit when rotating in one direction to reduce the pressing force on the pressing roller, the interference with the pressing unit is released when returning to the original position; A drive unit forcibly rotating the rotation lever in one direction during driving; And a control unit for selectively controlling the driving of the driving unit according to the input paper type.

The drive unit may be a solenoid connected to the rotation lever to selectively rotate the rotation lever at an angle.

The drive unit may include: a worm wheel coaxially mounted to the rotary lever; A worm connected to the worm wheel; And a motor for selectively forward / reverse rotation of the worm.

Hereinafter, a fixing apparatus of a laser printer according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a fixing apparatus of a laser printer according to an exemplary embodiment of the present invention includes a frame 10, a heating roller 11 rotatably installed on the frame 10, and a heating roller 11. Pressing pressure applied to the pressure roller 13 from the pressure roller 13 and the pressure unit 15 and the pressure unit 15 which elastically pressurize the pressure roller 13 to the heating roller 11 side. And a pressing force adjusting means 20 for adjusting the pressure.

The frame 10 is installed in the printer body, and wraps and protects the heating roller 11 and the pressure roller 13 and the like. The heater 14 for dissipating heat is installed in the heating roller 11. The heater 14 may be a halogen lamp, a coil resistor, or the like.

The pressure roller 13 is installed in the frame 10 to be in contact with the heating roller (11). As the printing paper passes between the pressure roller 13 and the heating roller 11, the toner image transferred to the printing paper is fused by high temperature / high pressure. The pressing roller 13 is moved minutely according to the magnitude of the pressing force by the pressing unit 15, so that the contact force with the heating roller 11 is variable. To this end, the rotating shaft of the pressure roller 13 is installed to be moved to the frame 10 minutely.

The pressurizing unit 15 includes a press lever 16 having one end rotatably connected to the frame 10 and a press spring 170 installed between the frame 10 and the press lever 16. The pressure lever 16 is installed so as to lean against the rotation shaft 13a so as to push the rotation shaft 13a of the pressure roller 13 toward the heating roller 11. The pressure spring 17 is a pressure lever 16. The upper end of the) is elastically pressed toward the heating roller (11).

The pressing force adjusting means 20 is for automatically adjusting the size of the pressing force acting between the heating roller 11 and the pressing roller 13 by the pressing unit 15 according to the type of printing paper input. . The pressing force adjusting means 20 includes a rotary lever 21 rotatably installed adjacent to the pressure lever 16, a driving unit 23 for selectively rotating the rotary lever 21 by a predetermined angle, and the driving unit ( 23 is provided with a control unit 25 for controlling the driving. The rotary lever 21 is rotatably installed at a predetermined position in the printer or the frame 10 about the rotary shaft 21a. When the rotary lever 21 is rotated in the clockwise direction by the driving unit 23, one end pushes the pressure lever 16 from the pressure lever 13 as shown in FIG. Therefore, the pressing force is applied to the pressure roller 13 by the pressure unit 15 to be less. Then, when the rotary lever 21 is returned to its original position, the pressure lever 16 is pushed by the pressure spring 17 to allow the pressure roller 13 to be pressurized with sufficient force. The driving unit 23 is preferably a solenoid connected to the rotary lever 21 to selectively interlock and return the rotary lever 21 according to an on / off operation. In this case, according to the on / off of the solenoid, the rotary lever 21 is converted into two modes to control the position of the pressure lever 16.

The controller 25 selectively controls the driving of the driving unit 23 according to the input paper type. That is, when the input paper type is general A4 paper or the like, the control unit 25 keeps the driving unit 23 in the off state. In addition, when the input paper type is an envelope thicker than normal paper, the controller 25 controls the driving unit 23 to be turned on. Then, as shown in Figure 2 by the drive of the drive unit 23, the rotary lever 21 and the pressure lever 16 is interlocked so that the pressing force between the pressure roller 13 and the heating roller 11 can be lowered. do.

An operation of the fixing apparatus of the laser printer according to the embodiment of the present invention having the above configuration will be described with reference to FIG. 3.

First, in the state where the pressure roller 13 presses the heating roller 11 as much as possible, as shown in FIG. 1, the printer is maintained in the print standby state. The print command is input from the user's PC during the print wait (S10). The controller 25 of the printer determines whether the target paper for the input print command is an envelope (S11). If the target paper is an envelope, the controller 25 selects an algorithm for printing the envelope (S12) and turns on the driver 20 (S13). Then, the solenoid 23 is turned on to rotate the rotary lever 21 in a clockwise direction, and the rotary lever 21 moves the pressure lever 16 toward the pressure member 17 as shown in FIG. 2. Let's do it. Thus, the pressing force against the heating roller 11 of the pressing roller 13 is reduced. In this state, when the envelope, from which the image is transferred in the predetermined developing portion, passes between the pressing roller 13 and the heating roller 11, envelope printing is completed (S14). At this time, since the pressing force between the pressing roller 13 and the heating roller 11 is reduced, even if an envelope thicker than the plain paper passes between the two rollers 11 and 13, the envelope passes normally without being wrinkled or wrinkled. .

On the other hand, after the envelope printing is completed, the control unit 25 turns off the driving unit 20 (S15). Then, the rotary lever 21 and the pressure lever 16 are returned to the state as shown in Fig. 1, and returned to a state suitable for fixing a general paper.

Of course, when the paper to be printed in step S11 is not an envelope, a fixing algorithm for each paper type, such as A4, A3, B4, etc., is selected (S16), and after the selected paper is fed (S17). Printing operation is performed (S18).

In addition, referring to FIG. 4, as another embodiment of the driving unit, a worm wheel 31 coaxially installed at the rotary lever 21, a worm 33 and the worm 33 connected to the worm wheel 31 may be disposed. A motor 35 for forward / reverse rotation at a predetermined speed is provided. The drive unit having such a configuration may selectively rotate the rotary lever 21 only as desired by a predetermined angle in various stages. Therefore, since the pressure lever 16 can be determined in various modes by the adjustable rotational posture, the pressing force between the pressure roller 13 and the heating roller 11 can be selectively and automatically adjusted. Therefore, it is possible to improve the quality of printing by automatically adjusting the fixing pressure when printing on various types of printing paper to prevent wrinkles or damage of the printing paper.

According to the fixing apparatus of the laser printer of the present invention as described above, it is possible to automatically adjust the fixing pressure according to the type of paper to be printed when printing normal paper or envelope.

Therefore, in particular, it is possible to achieve convenience in a network printer commonly used by several people, and to prevent deterioration of printing quality.

Claims (5)

A fixing apparatus of a laser printer which presses printing paper passing through a developing unit and fixes a toner image on the printing paper. A frame; A heating roller rotatably installed in the frame and having a heater installed therein; A pressure roller installed on the frame to be in contact rotation with the heating roller, and pressurizing the printing paper passing between the heating rollers; A pressurizing unit for elastically pressing the pressurizing roller toward the heating roller; And And a pressing force adjusting means for judging the type of the input printing paper and automatically adjusting the pressing unit according to the determined printing paper type to adjust the pressing force of the pressing roller against the heating roller. Fixing device for laser printers. According to claim 1, wherein the pressing unit, A pressure lever having one end rotatably installed on the frame and contacting the shaft of the pressure roller; And a pressure spring installed on the frame to press the pressure lever toward the pressure roller to transmit a pressing force to the heating roller. According to claim 1, wherein the pressing force adjusting means, A rotary lever which pushes the pressure unit in rotation in one direction to reduce the pressing force on the pressure roller and releases interference on the pressure unit when returning to the original position; A drive unit forcibly rotating the rotation lever in one direction during driving; And And a control unit for selectively controlling the driving of the driving unit according to the input paper type. The method of claim 3, wherein the driving unit, And a solenoid connected to the rotary lever to selectively rotate the rotary lever at a predetermined angle when driven. The method of claim 3, wherein the driving unit, A worm wheel coaxially mounted to the rotary lever; A worm connected to the worm wheel; And And a motor for selectively rotating the worm in a forward / reverse direction.