KR100643382B1 - Printing apparatus and method of printing speed control - Google Patents

Abstract

The present invention relates to an image forming apparatus and a method of changing a printing speed of an image forming apparatus, wherein the laser beam including the print data is reflected by a polygon mirror to be irradiated to a photosensitive drum to form a latent image. A laser generator for irradiating a latent image on the photosensitive drum; A motor driving part including a feeding roller for transferring paper and a driving motor for driving the photosensitive drum at a predetermined rotational speed; When the printing speed is changed to one-nth according to the type of paper, the laser generation unit is controlled to generate one data synchronization signal for every nth side of the polygon mirror, and the rotational speed of the driving motor is one-nth. And a printing speed changing method of the image forming apparatus and the image forming apparatus. Thereby, the printing speed can be changed accurately even by a simple method.

Description

How to change printing speed of image forming apparatus and image forming apparatus {PRINTING APPARATUS AND METHOD OF PRINTING SPEED CONTROL}

1 is a view showing the configuration of a laser scanning unit of a conventional image forming apparatus;

2 is a block diagram showing a configuration of an image forming apparatus according to the present invention;

3A and 3B are graphs showing a comparison of the period change of each signal in the laser scanning unit of the image forming apparatus according to the prior art and the present invention;

4 is a flowchart illustrating a printing speed changing method of the image forming apparatus according to the present invention.

<Description of reference numerals for main parts of the drawings>

10 polygon mirror 13 lens

17: light receiver 20: photosensitive drum

30: laser generating unit 40: control unit

60: motor drive part

The present invention relates to an image forming apparatus and a printing speed changing method of the image forming apparatus.

The laser printer is a representative image forming apparatus. As shown in FIG. 1, a laser beam emitted from the laser generation unit 30 by a video signal of an input image is irradiated to the photosensitive drum 20, and a photosensitive drum ( 20 is a device that reproduces an image image by spraying toner on a latent image formed in 20) and transferring the toner onto a medium such as paper.

Recently, with the development of image forming technology, the printing speed is gradually increasing, and at the same time, the demand for image formation on printing paper having various shapes and thicknesses, such as envelopes and cards, in addition to commonly used standard paper is increasing.

However, when printing thick and rough paper such as envelopes at a high printing speed, the paper is transported at a high speed so that fixing to fuse the toner transferred to the paper completely onto the paper cannot be performed properly. A question arises.

In the related art, in order to secure fixing property according to the paper, a method of increasing the temperature of the heating roller of the fixing unit or increasing the pressure of the pressure roller and increasing the radius of the heating roller has been proposed. However, in the case of the above-described method, in addition to the increase in the production cost, it is not possible to continuously raise the temperature of the heating roller and the pressure of the pressing roller as the paper feed speed increases. In the case of conveyed by air, the air is injected into the bag inlet, which increases the load on the driving motor and may cause outage of the driving motor.

On the other hand, in addition to the method of securing the fixing while maintaining the printing speed as described above, while reducing the paper feed speed to have a sufficient time required for the paper is fixed, while slowing the rotational speed of the polygon mirror (10) In (20), a method of matching the rate of latent image formation with the paper feed speed has been proposed.

However, as described above, the method of lowering the speed of the polygon mirror 10 may cause deterioration of image quality due to vibration generated by changing the rotation speed, and there is a problem such as noise.

Accordingly, it is an object of the present invention to provide an image forming apparatus and a printing speed changing method of an image forming apparatus that can change the printing speed accurately in a simple manner without using an additional apparatus or changing the rotation speed of the polygon mirror. .

In order to achieve the above object, the present invention is an image forming apparatus in which a laser beam including print data is reflected by a polygon mirror to be irradiated to a photosensitive drum to form a latent image. A laser generating unit to form; A motor driving part including a conveying roller for conveying paper and a driving motor for driving the photosensitive drum at a predetermined rotational speed; When the printing speed is changed to one-nth according to the type of paper, the laser generation unit is controlled to generate one data synchronization signal for every nth surface of the polygon mirror, and the rotational speed of the driving motor is n minutes. It characterized in that it comprises a control unit for controlling the motor driving unit to be one.

In addition, in a method of changing a printing speed of an image forming apparatus in which a laser beam including print data is reflected by a polygon mirror to be irradiated to a photosensitive drum to form a latent image, the printing speed of the paper on which the image is to be formed is compared with the current printing speed. Determining whether to change the current print speed; When the current printing speed is changed to one-nth according to the appropriate printing speed, the laser generating unit controls the laser generating unit to generate one data synchronization signal for every nth surface of the polygon mirror, and the conveying roller and the photosensitive paper for conveying paper. And controlling the motor driving unit so that the rotational speed of the driving motor for driving the drum is one-nth.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to the description, the same components that perform the same functions as the conventional image forming apparatus will be described with the same reference numerals.

2 is a block diagram showing the configuration of an image forming apparatus according to the present invention.

The printing speed of the image forming apparatus depends on the paper feeding speed at which the paper on which the image is formed is conveyed and the image forming speed at which the image is formed on the paper being conveyed. The speed at which the image is formed is the speed at which the latent image is formed on the photosensitive drum 20.

Looking at the process of forming a latent image on the photosensitive drum 20 with reference to the drawings, the central processing unit (hereinafter referred to as CPU) 73 that receives and processes the print data from the host computer 73 prints stored in the memory The data is sent to the laser generator 30 to be described later. The laser generator 30 generates a laser beam including the print data, and the generated laser beam is reflected by the polygon mirror 10 and irradiated to the photosensitive drum 20.

The polygon mirror 10 rotates about a predetermined axis, and the outer circumferential surface is divided into a predetermined number of surfaces so that the laser beam is reflected from each surface. The number of reflective surfaces of the polygon mirror 10 is not limited, but may have six surfaces. Since one side of the polygon mirror 10 reflects a laser beam including print data corresponding to one line of the paper on which the image is formed, the number and rotational speed of the reflection surface of the polygon mirror 10 are the print speed of the image forming apparatus. Has a relationship with That is, when the rotational speed of the polygon mirror 10 is increased, the printing speed is increased by that much. On the other hand, the laser beam reflected by the polygon mirror 10 is applied to the photosensitive drum 20 through the lens 13 and the reflector 15 to form a light path so that the laser beam is constantly irradiated on the photosensitive drum 20. The latent image is formed on the photosensitive drum 20 by irradiation.

The laser generation unit 30 includes the print data stored in the memory by the CPU 73 in the laser beam to irradiate the polygon mirror 10. Here, the laser beam irradiated by the laser generator 30 includes print data corresponding to one line of the paper on which an image is formed, and the print data corresponding to each line is a data synchronization signal generated by the light receiver 17 to be described later. Is controlled by the CPU 73 and irradiated.

When the laser beam including the print data is generated in the laser generator 30, the laser beam is reflected on the reflective surface of the rotating polygon mirror 10 and irradiated to the photosensitive drum 20. At this time, the incident direction of the laser beam is always constant, but since the polygon mirror 10 is rotating, the reflection angle of the laser beam is changed according to the rotation angle of the polygon mirror 10. Therefore, the laser beam irradiates the photosensitive drum 20 with the print data corresponding to one line while being irradiated from c of FIG. 1 and irradiated from d to e.

On the other hand, one side of the photosensitive drum 20 is provided with a light receiving unit 17 so that the laser beam including the print data can be detected by the light receiving unit 17 after being irradiated to the photosensitive drum 20. When the light receiving unit 17 detects the laser beam, the light receiving unit generates a data synchronization signal Hsync, and when the CPU 73 detects this signal, the light receiving unit 17 controls to output print data corresponding to one next line. Therefore, the data synchronization signal should be generated for each surface of the polygon mirror 10 for continuous output. For this purpose, the laser generator 30 lasers at the position of the light receiver 17 outside the region of the photosensitive drum 20. The beam should be irradiated.

Therefore, if the data synchronous signal is not generated, since the CPU 73 does not process the print data corresponding to the next line and cannot proceed with printing, the printing speed can be adjusted by adjusting the generation period of the data synchronous signal.

The controller 40 determines the type of paper to be outputted through the driver 71 when selecting a paper type through the driver 71 or when detecting the type of paper to be fed. And first determine whether to change the current printing speed by comparing the proper printing speed according to the set paper type.

Herein, the controller 40 may include a memory in which data regarding an appropriate printing speed according to the type of paper is stored in advance.

When the printing speed is changed based on the determination result, the controller 40 determines how much the current printing speed is to be delayed to control the laser generator 30 and the motor driver 60 to be described later. That is, when the current print speed is reduced to one-nth according to the type of paper to be loaded, the control unit 40 changes the generation period of the data synchronization signal generated by the light receiving unit 17 to n times, and at the same time The motor driving unit 60 is controlled so that the rotational speed is changed to nth. Here, the rotation speed of the polygon mirror 10 is not changed.

An embodiment in which the printing speed is cut in half will be described with reference to FIGS. 3A and 3B. 3A and 3B are graphs comparing the generation periods of the respective signals generated in the laser scanning unit of the image forming apparatus, and FIGS. 3A and 3B show irradiation positions of the laser beam, and are shown in FIG. It corresponds to one line of paper.

Referring to FIG. 3A, when the laser beam is generated at the position of the light receiver 17 so that the laser beam can be detected by the light receiver 17 in the laser generator 30 (see a of FIG. 3A), The light receiving unit 17 senses the laser beam to generate a data synchronization signal (see b in FIG. 3A). The data synchronization signal is received by the CPU 73 and after a predetermined time has passed, the laser beam including the print data is irradiated from the laser generator 30 (see c in FIG. 3A), and the irradiation of the print data is performed. After completion (see e of FIG. 3A), the laser beam is sensed again by the light-receiving unit 17 after a predetermined time, and the data synchronization signal is generated.

Here, the time from the detection of the laser beam to the light receiving unit 17 after the detection of the laser beam by the light receiving unit 17 is referred to as Ta, which means that one side of the polygon mirror 10 is rotated from a predetermined position, This is equal to the time for reaching the predetermined position. .

Therefore, when the printing speed is to be reduced by half, the rotation speed of the polygon mirror 10 is left unchanged, and the detection period of the laser beam detected by the light receiving unit 17 is changed. That is, as shown in FIG. 3B, when the laser beam reaches the position of the light receiver 17 after irradiating the print data for one line, the controller 40 may not irradiate the laser beam from the laser generator 30. As a result, the data synchronization signal is not generated in the light receiving unit 17. If a data synchronization signal is not generated, the print data is not output from the CPU 73 as described above, so that one of the reflective surfaces of the polygon mirror 10 rotating at the same speed reflects valid print data, but the next surface is valid printing. Since the data cannot be reflected, the image forming speed is cut in half. Therefore, in FIG. 3B, the period Tb at which the laser beam is detected by the light receiving unit 17 is twice the Ta in FIG. 3A.

On the other hand, when the printing speed is reduced to one third, the laser generator 30 is detected so that the light receiving unit 17 detects one laser beam each time three surfaces of the polygon mirror 10 rotate. You can control it.

Here, the embodiment for changing the printing speed is not limited to the above-described example, and of course, various speed changes corresponding to the number of reflection surfaces of the polygon mirror 10 are possible.

Therefore, the image forming apparatus according to the present invention can simply change the image forming speed by controlling the laser generating unit 30 without installing an additional device or changing the rotating speed of the polygon mirror 10, so that the rotating speed Vibration and noise are not generated due to the change, which can prevent deterioration of image quality.

On the other hand, the control unit 40 may control the motor drive unit 60 to reduce the rotational speed of the photosensitive drum 20 and the feed roller for conveying the paper to change the rotational speed of the drive motor in accordance with the appropriate printing speed.

With this configuration, the printing change method of the image forming apparatus according to the present invention will be described with reference to FIG.

First, when a paper is selected through a user's paper setting or a method of detecting the paper being fed, the controller 40 determines whether to change the current print speed by calculating an appropriate print speed according to the paper and comparing it with the current print speed. Determine (S100).

According to the change, the controller 40 controls the laser generator 30 to change the detection period of the laser beam detected by the light receiving unit 17 from the current detection period Ta to an appropriate detection period Tb (S110). ).

At the same time, the control unit 40 controls the motor driving unit 60 to change the rotational speed of the photosensitive drum 20 and the driving motor driving the feed roller from the current rotational speed Va to the proper rotational speed Vb (S110). . After changing the printing speed, the image forming apparatus starts printing according to the appropriate printing speed (S120).

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. .

 As described above, according to the printing speed changing method of the image forming apparatus and the image forming apparatus according to the present invention, the printing speed can be accurately changed even by a simple method.

Claims (2)

An image forming apparatus in which a laser beam including print data is reflected by a polygon mirror to be irradiated to a photosensitive drum to form a latent image. A laser generator for irradiating the laser beam to form a latent image on the photosensitive drum; A motor driving part including a conveying roller for conveying paper and a driving motor for driving the photosensitive drum at a predetermined rotational speed; When the printing speed is changed to one-nth according to the type of paper, the laser generation unit is controlled to generate one data synchronization signal for every nth surface of the polygon mirror, and the rotational speed of the driving motor is n minutes. And a control unit for controlling the motor driving unit to be one. A method of changing the printing speed of an image forming apparatus in which a laser beam including print data is reflected by a polygon mirror to be irradiated to a photosensitive drum to form a latent image. Determining whether to change the current print speed by comparing the current print speed with the proper print speed of the paper on which the image is to be formed;  When the current printing speed is changed to one-nth according to the appropriate printing speed, the laser generating unit controls the laser generating unit to generate one data synchronization signal for every nth surface of the polygon mirror, and the conveying roller and the photosensitive paper for conveying paper. And controlling the motor driving unit so that the rotational speed of the driving motor for driving the drum is one-nth.

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