JP2003011424A - Image forming apparatus and method of controlling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing extension of a time period for printing along with change of a rotation speed of a scanner as little as possible. SOLUTION: This image forming apparatus has a plurality of process speeds or and a plurality of resolutions. In this image forming apparatus, when a print job is finished and the rotation speed of the scanner at the next print job is changed, a timing of finishing the driving of rotation of the scanner or changing the rotation speed thereof can be adjusted or changed. When the process speed is switched from high to low or the resolution is switched from high to low, the driving of rotation of the scanner is quickly turned off without maintaining the driving of the rotation until going into rear rotation after the printing operation is completed or until finishing the rear rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printer, a copying machine, and an electrostatic recording device.

[0002]

2. Description of the Related Art FIG. 8 shows a schematic structure of a conventional image forming apparatus.

In FIG. 8, reference numeral 100 denotes an external device such as a host computer, which sends image data and a print command to the image forming apparatus. A formatter 101 of the image forming apparatus expands image data sent from the host computer 100 such as the external device into bitmap data and performs signal conversion so that laser light emission can be performed. The converted signal is laser exposed.

Reference numeral 1 is a photosensitive drum, which rotates in a direction of an arrow at a predetermined speed. Reference numeral 2 denotes a charging roller for performing primary charging, which uniformly charges the surface potential of the photosensitive drum 1. A laser beam 3 is turned on / off based on the input image data.
FF control is performed, and the photosensitive drum 1 is scanned through a polygon mirror (not shown) to form a latent image.

A developing device 4 visualizes the electrostatic latent image formed on the photosensitive drum 1 with a developer.

Reference numeral 26 is a paper feed cassette for accommodating recording materials P which are recording media in a stack. A paper feed roller 22 feeds the recording material P to the position of the registration roller 24 by driving the paper feed roller 22.

A transfer roller 5 transfers the toner image visualized on the photosensitive drum 1 to the recording material P. A cleaner 7 removes toner remaining on the surface of the photosensitive drum 1.

Here, the photosensitive drum 1, the charging roller 2, the developing device 4, and the cleaner 7 are generally housed in an integral cartridge and can be easily replaced by the user.

A fixing device 6 fixes the toner image transferred onto the recording material P by applying heat and pressure to the recording material P. The recording material P fixed is discharged to a discharge tray or the like.

In recent years, there has been a marked social trend toward higher image quality of electrophotographic apparatuses, and there is a tendency to shift to high resolution printers, and 600 dpi and 1200 dpi printers have become common.

[0011]

However, the image forming apparatus such as the above-mentioned conventional example has the following problems.

That is, as the printer speed increases, it is necessary to operate at full speed in the main print mode and to operate at a slower speed in the print mode that can be limited to a special application, rather than necessarily performing all printing at one process speed. There are increasing cases where it is more advantageous to respond with speed.

Considering the paper type as the recording material,
The main print modes are A4 and LTR size,
In addition, when the paper type is a general plain paper, the special application is, for example, a so-called rough paper called a Bond paper or a Laid paper with a rough surface.

Since it is difficult to fix rough paper, it is more rational to print at a low speed by slowing down the process speed, rather than setting a strong fixing device capable of fixing at a full speed, in consideration of peculiarities.

Considering the paper feeding method, the main mode is automatic paper feeding from a cassette, which is desired to be capable of printing at full speed.

However, when using a paper feed port for irregular size or special paper such as the manual paper feed method, only a low process speed can be supported as compared with the case where a paper feed mechanism for full speed is provided. Such a mechanism is sufficient.

For the reasons described above, there is a need for a printer with multiple process speeds.

As another example, one printer has two kinds of resolutions of 600 dp due to the recent increase in resolution.
There are printers having i, 1200 dpi, etc.

For normal use, 600 dpi is sufficient, but 1200 d is especially desirable when printing with high image quality.
This is a case of switching to pi for use.

In the case of the process speed switching and the resolution switching as described above, the scanner driving rotation speed (the rotation speed of the polygon mirror) is changed to handle it.

However, since the polygon mirror of the scanner rotates at a high speed, it takes time to change the number of rotations due to the influence of inertia. Especially when trying to reduce from high speed to low speed.

Further, generally, the rotational driving of the scanner is continued until the post-rotation for finishing the printing operation is finished. The reason is that if the drive is immediately turned off at the time when the image formation on the photosensitive drum during the printing operation is completed, it takes time for the scanner rotation speed to reach a predetermined value when the next print job continues. This is because it takes time to print the result.

On the contrary, when the next print job needs to change the number of rotations of the scanner, the function for preventing the print time from being lengthened causes a problem that the print takes a long time due to the warp. There is.

The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus and a control method capable of minimizing the extension of the printing time due to the change of the number of rotations of the scanner. To do.

[0025]

The present invention can solve the above-mentioned problems by providing the following constitutions.

(1) In an image forming apparatus having a plurality of process speeds or a plurality of resolutions, when the number of rotations of the scanner is changed in the next print job after the print job is finished, An image forming apparatus that adjusts / changes the timing of ending the scanner rotation drive or changing the scanner drive rotation speed.

(2) When the process speed is switched from high speed to low speed, or when the resolution is switched from high resolution to low resolution, until the start of post-rotation at the end of the printing operation or until the end of post-rotation, the scanner The image forming apparatus according to item (1), wherein the scanner rotation drive is quickly turned off without maintaining the rotation drive.

(3) In an image forming apparatus having a plurality of process speeds, when a series of print jobs is completed, the rotation speed of the scanner is changed to a high speed by increasing the process speed in the next print job. In addition, when a predetermined condition is satisfied, the image forming apparatus is characterized in that the printing operation at a low process speed is maintained without increasing the process speed.

(4) A method of controlling an image forming apparatus having a plurality of process speeds or a plurality of resolutions, wherein when a series of print jobs is completed, the process speed or resolution is changed in the next print job. A method of controlling an image forming apparatus, comprising the step of adjusting / changing the timing of ending the scanner rotation drive or changing the scanner drive rotation speed at the end of the current printing operation when the rotation speed of the scanner is changed.

(5) A method of controlling an image forming apparatus having a plurality of process speeds, wherein when a series of print jobs is completed, the speed of the scanner is increased by increasing the process speed in the next print job. When changing, if a preset predetermined condition is satisfied, the image forming apparatus includes a step of maintaining the slow print operation at a low process speed without increasing the process speed. Control method.

That is, specifically, when the process speed is switched from high speed to low speed, or when the resolution is switched from high resolution to low resolution, until the rotation after the end of the print operation or the end of the post-rotation is completed. Do not keep the rotational drive of the scanner on its side, but turn it off quickly.

As a result, when the next print job to be printed at a low print speed comes while printing at a high print speed, conventionally, the scanner drive is turned off after completion of the post-rotation and the rotation is lowered. After that, the low-speed scanner rotation drive was started, and the rotation was stable, and printing was finally performed.

In contrast, the present invention allows the preparation for low speed scanner rotation to be immediately initiated at the end of imaging the previous print job.

As a result, it is possible to minimize the extension of the printing time for changing the number of rotations of the scanner.

Further, in an image forming apparatus having a plurality of process speeds, when a series of print jobs is completed and the driving speed of the scanner is changed to a high speed by increasing the process speed in the next print job, When predetermined conditions are met, the process speed is not increased and printing is performed at a low process speed, so the time for changing the scanner rotation speed can be eliminated and the extension of the print time can be suppressed. You can

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image forming apparatus according to the present invention will be described below.

FIG. 1 is an explanatory side sectional view showing a schematic structure of an image forming apparatus according to the present invention, FIG. 2 is an explanatory view showing a transition state of the scanner rotation speed in this embodiment, and FIG. 4 is an explanatory diagram showing a control sequence of the image forming apparatus according to the first embodiment, FIG. 4 is an explanatory diagram showing a control sequence of the image forming apparatus according to the comparative conventional example, and FIG. 5 is a second embodiment according to the present invention. 6 is an explanatory view showing the control sequence of the image forming apparatus in FIG. 6, FIG. 6 is an explanatory view showing the control sequence of the image forming apparatus in the third embodiment of the present invention, and FIG. 7 is the number of prints in the embodiment of the present invention. FIG. 8 is a side cross sectional explanatory view showing a schematic configuration of an image forming apparatus in a conventional example, and FIG.

(First Embodiment) In FIG. 1, reference numeral 1 is a photosensitive drum as an image carrier, which is formed by forming a photosensitive material such as OPC or amorphous silicon on the surface of a cylindrical substrate such as aluminum or nickel. ing.

The surface of the photosensitive drum 1 is uniformly charged by the charging roller 2 as a charger. Next, the laser light 3 which is the exposure means is ON / OFF controlled according to the image information to perform scanning exposure, and an electrostatic latent image is formed on the photosensitive drum 1. This electrostatic latent image is developed and visualized by the developing device 4.

As a developing method, a jumping developing method,
A two-component developing method or the like is used, and it is often used in combination with image exposure and reversal development.

The recording material P is fed from the manual feed tray 29 or the paper feed cassette 26, taken out by the paper feed rollers 22 and 27, the recording material size is detected by the trailing edge detection sensor 23, and the registration roller pair 24 is used. Sent to. The recording material size may be determined by the resist sensor 5. In addition to the paper feed cassette 26, the paper feed port also has a manual paper feed port 28.

The paper feed cassette 26 has a capacity to store 500 sheets of paper, while the manual feed tray 29 has a capacity to store about 50 sheets.

The recording material P is supplied by the registration roller pair 24 to the transfer nip portion formed by the photosensitive drum 1 and the transfer roller 5 in synchronization with the toner image formed on the surface of the photosensitive drum 1. At the transfer nip portion, the photosensitive drum 1
The upper toner image is transferred to the recording material P by the action of a transfer bias by a power source (not shown). The recording material P holding the toner image is conveyed to the fixing device 6, heated and pressed at the nip portion of the fixing device 6, the toner image is fixed on the recording material P, becomes a permanent image, and is discharged out of the apparatus. .

On the other hand, the transfer residual toner remaining on the photosensitive drum 1 after the transfer is removed from the surface of the photosensitive drum 1 by the cleaner 7.

The image forming apparatus of this embodiment has two kinds of process speeds, and in the case of paper feeding from the paper feeding cassette 26, the process speed is about 150 mm in a printer which prints 24 ppm of A4 size paper (24 sheets are printed per minute). /
sec.

From the manual paper feed port 28, A4 size is 12 ppm and the process speed is about 75 mm / se.
c. This is because in consideration of the frequency of use and the number of sheets to be used in the manual paper feed port 28, the simplification of the paper feed mechanism and the cost are prioritized over feeding at full speed. In either case, the resolution is 600 dpi.

FIG. 2 shows changes in the number of rotations of the scanner when printing is performed.

When the print signal arrives, the scanner rotation drive is started. The scanner rotation speed rises from 0 toward the target rotation speed of 32000 rpm. This startup takes about 3 seconds. Even if the target speed is reached once, overshoot occurs, so it takes about 2 seconds to stabilize at that speed.

When the rotation speed is stable, it is possible to form an image on the photosensitive drum 1. When a predetermined number of prints are completed, the scanner rotation drive is turned off at a predetermined timing. The rotation of the scanner is then affected by the inertia of the polygon mirror, the scanner motor, etc., and the rotation does not stop immediately but gradually decreases.

As shown in FIG. 2, it takes about 20 seconds for the portion marked "falling" to completely stop.

Here, as the polygon mirror (not shown), an eight-sided mirror is used in order to suppress the scanner rotation at full speed to about 32000 rpm. Process speed 7
Scanner rotation speed is 16000r for 5 mm / sec
It is about pm. It takes about 5 seconds to turn off the scanner rotation drive rotating at 32000 rpm and reach 16000 rpm or less.

As an example to which the present invention is applied, FIG. 3 shows an example of a case where continuous printing paper is printed from a paper feeding cassette and then printing is performed from a manual paper feeding port.

The main motor drives the paper feed mechanism, paper transport mechanism, cartridge (photosensitive drum, charging roller, developing device), transfer roller, fixing device, paper discharging mechanism and the like.

First, in continuous two-sheet printing from the cassette, the cassette paper feeding mechanism operates at the same time as the start of pre-rotation, which is a preparatory operation for printing operation. Primary charging, laser exposure,
Develop, transfer, and fix sequentially to print two sheets. Scanner rotation is driven by the scanner motor. As described above, since it takes time to start up the scanner, the scanner drive is started immediately when the print signal arrives.

The rotation drive of the scanner of this embodiment is shown by a solid line. The next print signal came when the second image rotation was completed and the post-rotation was started. For the next print, the paper feed port was manually fed, so the process speed was changed. In the present invention, the rotation drive of the scanner is stopped to prepare for low speed rotation in the next printing. The scanner rotation decreases while the printer is performing post-rotation, which is the print process end operation, and the scanner startup operation is started immediately when the next print comes. For the next printing from the manual paper feed port, after the main motor is once stopped, it immediately rotates at a low process speed to start printing. The subsequent operation is the same.

For reference, the case of the comparative conventional example is shown by the chain double-dashed line, but the rotation of the scanner is maintained until the end of the post-rotation.

Also in the present invention, after continuous two-sheet printing,
If the next print is again fed from the same cassette, the process speed is not changed, so the scanner rotation is maintained until the end of the post-rotation. This is because the rotation stability of the scanner is faster.

FIG. 4 shows each control sequence when the same printing is performed in the comparative conventional example. Since the scanner rotation drive is maintained until the end of the post-rotation, it takes time for the rotation of the scanner motor to be too fast at the next pre-rotation of printing from the manual feed port, and it takes time to stabilize at the predetermined 16000 rpm. Is longer than usual.

The pre-rotation in which the portion surrounded by the hatched square in the figure becomes long, takes about 5 seconds in the comparative conventional example.

In the present embodiment, the case where a print signal from a different paper feed port is received during rotation after printing two continuous sheets, the number of print sheets is not limited to this.

Even when the process speed is constant and the high resolution printing is followed by the low resolution printing, the same idea can be applied in that the scanner rotation is switched from the high rotation to the low rotation. Similar to the example, the effect of shortening the printing time can be exhibited.

As described above, in the present embodiment, the effect of the present invention is shown when the scanner rotation is switched from high rotation to low rotation.

(Second Embodiment) This embodiment is the second embodiment of the present application.
It is an example of. The configuration of the image forming apparatus is similar to that of FIG. 1 of the first embodiment. In the present embodiment, a case where the scanner rotation is switched from low rotation to high rotation is shown.

FIG. 5 shows each control sequence. In this embodiment, first, two sheets are continuously printed from the manual paper feed port. First
Printing is performed at a low process speed from the manual paper feed port as in the above embodiment. The next print signal comes during the post-rotation, but when this is from the paper feed cassette 26, the scanner rotation speed becomes high because the process speed is switched to a high speed.

In this embodiment, the scanner rotation is started at a high speed immediately when the print signal comes during the rotation after the printing from the manual feed. As a result, in the next pre-rotation, the rotation of the scanner is fast and stable at a high speed, so the rotation of the scanner hardly prolongs the printing time.

The main motor is temporarily stopped for switching the process speed and restarted at a high process speed.

In the present invention, even when the main motor is temporarily stopped, the scanner motor is still starting up for high speed rotation.

On the other hand, in the conventional method, the main motor switches the speed and the scanner also switches the speed at the same time, so that it takes more time than the present invention.

Although the process speed is constant,
The present invention is also effective when switching from low-resolution printing to high-resolution printing because the same applies in that the scanner rotation switches from low speed to high speed.

Up to this point, an example has been shown in which the process speed is switched by switching the paper feed port. Not limited to this, for plain paper, the process speed is high, but for rough paper, an example of switching to a slower process speed because fixing is disadvantageous, and for paper sizes of A4 and LTR, a high process speed. However, the paper size is B5, A
The present invention is also effective in that the driving speed of the scanner is switched even in the case of switching to a low process speed in the case of small size such as 5, envelopes and postcards.

(Third Embodiment) This embodiment is the third embodiment of the present application.
It is an example of. The configuration of the image forming apparatus is similar to that of FIG. 1 of the first embodiment. In this embodiment, when the next print comes during the post-rotation after printing at the low process speed, and the print is originally the content to be printed at the high process speed, the predetermined condition is satisfied. This is an example in which a print with a low process speed is printed.

FIG. 6 shows each control sequence. In this embodiment, first, two sheets are continuously printed from the manual paper feed port. First
Printing is performed at a low process speed from the manual paper feed port as in the above embodiment. The next print signal comes during the post-rotation, but if it is from the paper feed cassette 26, the scanner drive rotation should be high speed because the process speed is originally switched to high speed.

In the present embodiment, whether or not to switch at high speed is actually switched to at high speed as described in the second embodiment only when a condition is set and applicable. The condition in this embodiment is only when the number of prints at the next high process speed is 5 or more.

FIG. 7 is a graph showing the number of prints from the paper feed cassette and the required time in each case. When switching to a high process speed and printing after printing at a low process speed, time is required for speed switching, but when the number of prints is large, the total time becomes short.

On the other hand, if printing is performed at a low process speed and then printing is performed at a low process speed,
The total time is short at the beginning because there is no time required for speed change. However, as the number of prints increases, the time required for printing warps longer.

In the present embodiment, this boundary is five, so only when the number of prints to be printed next is four or less, it is possible to print at a low speed even when the original process should be switched to the high process speed for printing. It is the one. The number of sheets to be switched is not limited to five, and may be set to an optimum number according to the model and conditions.

It is also possible for the user to manually set whether to print at low speed or at high speed.

As described above, in the present embodiment, it is shown that the time required for printing can be shortened even if the process speed is low by avoiding changing the scanner rotation speed depending on the situation.

Such a mode is very effective in the case of printing a small number of prints by frequently switching the paper feed port, or in the usage of alternately printing a small number of different paper types.

[0080]

As described above, according to the present invention, an image forming apparatus having a plurality of process speeds or a plurality of resolutions should print at a low print speed when printing at a high print speed. When the next print job arrives, the preparation for the low-speed scanner rotation can be started immediately after the image formation of the previous print job is completed, so that the extension of the print time for changing the scanner rotation speed is minimized. There is an effect that can be suppressed to.

Even if the next print job is supposed to be printed at a high process speed by nature, if the predetermined condition is met, printing is performed at a low process speed to change the number of rotations of the scanner. This has the effect of suppressing the extension of printing time.

[Brief description of drawings]

FIG. 1 is a side sectional explanatory view showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a transition status of the scanner rotation speed in the present embodiment.

FIG. 3 is an explanatory diagram showing a control sequence of the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a control sequence of an image forming apparatus according to a comparative conventional example.

FIG. 5 is an explanatory diagram showing a control sequence of the image forming apparatus according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a control sequence of the image forming apparatus according to the third embodiment of the present invention.

FIG. 7 is an explanatory diagram showing the relationship between the number of prints and the time required for printing in the embodiment according to the present invention.

FIG. 8 is an explanatory side sectional view showing a schematic configuration of an image forming apparatus in a conventional example.

[Explanation of symbols]

1 photosensitive drum 2 charging roller 3 laser light 4 developing device 5 Transfer roller 6 fixing device 7 cleaner P Recording material 22 Paper feed roller 23 Rear end detection sensor 24 Registration roller 25 Registration sensor 26 paper cassettes 27 paper feed roller 28 Manual feed slot 29 Bypass tray 101 formatter

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiko Suzuki             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2C362 BA33 BA34 BA35 CB02 CB07                       CB13 CB47                 2H027 EA02 EA18 EB00 EC02 ED06                       EE03 EE04 EF06 EF11 EF12                       EF13                 2H076 AB02 AB12 AB16

Claims (5)

[Claims] 1. An image forming apparatus having a plurality of process speeds or a plurality of resolutions, wherein when the number of rotations of the scanner is changed in the next print job after the print job is completed, the scanner at the end of the current print operation is performed. An image forming apparatus, which adjusts / changes the timing of rotation driving end or scanner driving rotation speed change. 2. When the process speed is switched from high speed to low speed, or when the resolution is switched from high resolution to low resolution, the rotation of the scanner is performed until the start of the post-rotation at the end of the printing operation or the end of the post-rotation. 2. The image forming apparatus according to claim 1, wherein the scanner rotation drive is quickly turned off without maintaining the drive. 3. An image forming apparatus having a plurality of process speeds, wherein when a series of print jobs is completed, the number of rotations of the scanner is changed to a high speed by increasing the process speed in the next print job. An image forming apparatus, characterized in that when a predetermined condition is satisfied, the process print speed is not increased and the low-speed process speed print operation is maintained. 4. A method of controlling an image forming apparatus having a plurality of process speeds or a plurality of resolutions, wherein when a series of print jobs is completed, the scanner is changed by changing the process speed or the resolution in the next print job. The method for controlling an image forming apparatus includes the step of adjusting / changing the timing of ending the scanner rotation drive or changing the scanner drive rotation speed at the end of the current printing operation when the rotation speed of the image forming apparatus is changed. 5. A method of controlling an image forming apparatus having a plurality of process speeds, wherein when a series of print jobs is completed, the rotation speed of the scanner is changed to a high speed by increasing the process speed in the next print job. If the predetermined conditions that are set in advance are satisfied,
A method of controlling an image forming apparatus, comprising a step of maintaining a low-speed process speed print operation without increasing the process speed.