JP2001281955A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of obtaining a stable first copying time in the case of starting the following image forming operation based on the detection of an image positioning mark even under a condition provided with plural kinds of process linear velocity. SOLUTION: Under the condition provided with plural kinds of process linear velocity capable of dealing with various kinds of resolution changes, etc., a stoppage timing (DL-L 9 portion) of stopping a drum motor for an image carrier, etc., in accordance with the process linear velocity at the stoppage is changed with giving considerations to the actual deviation in accordance with the process linear velocity. For example, when the linear velocity is 156 mm/s, the motor is stopped after 365 ms elapse after turning off a paper transfer charger, but, when the linear velocity is 104 mm/s, the motor is stopped at the point of time of 727.5 ms which is obtained by adding the actual deviation of 180 ms to the one and half times as much as the ratio of the linear velocity, that is, 547.5 ms. Then, the stable first copying time is maintained in the case of starting the following image forming operation based on the detection of the image positioning mark on the intermediate transfer body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method using an electrophotographic process capable of forming a color image or the like on a transfer material by providing an intermediate transfer member capable of transferring an image on an image carrier such as a photosensitive member a plurality of times. The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus using an electrophotographic process, several methods have been proposed as means for changing the resolution of an image using a single image forming apparatus. As one of the methods, a method is known in which the resolution is changed by changing the laser writing density and the rotation speed of the photosensitive member as the image carrier without changing the rotation speed of the polygon motor. This means that the resolution can be changed by changing the number of rotations of the polygon mirror.However, as the resolution increases, the number of rotations of the polygon motor increases, and when the rotation becomes extremely high, the configuration of the polygon mirror increases. This is because it has to be changed drastically, which increases the cost.

For example, Japanese Patent Application Laid-Open No. 1-2224780 discloses a method in which the writing density of laser light is changed in accordance with the resolution, and the process speed is also changed. Further, it has been proposed to change the latent image forming condition, the developing condition, the transfer condition, and the fixing condition together with the change of the process speed.

On the other hand, the following is known as a conventional example for changing the linear speed of image formation on a photosensitive member and the linear speed of transfer / fixing. That is, an image in which single-color images of different colors are sequentially superimposed on the intermediate transfer body with reference to the detection of the alignment mark attached to the intermediate transfer body, and the image superimposed on the intermediate transfer body is transferred to transfer paper. In the forming device, cardboard or O
In order to prevent heat from being taken by the transfer paper when fixing the image on the transfer paper such as an HP sheet and to reduce the fixing efficiency, the speed of the intermediate transfer body is reduced after transferring the image to the intermediate transfer body. There is a type in which an image is transferred to a transfer paper such as a thick paper or an OHP sheet.

For example, according to Japanese Patent Application Laid-Open No. 4-67174, after the full-color toner image for one page of the transfer paper is completely transferred to the intermediate transfer member, the speed of the intermediate transfer member is substantially equal to the speed of the fixing device. By decelerating to a speed, a high-quality image can be obtained even in a small fixing device full-color printing. According to Japanese Patent Application Laid-Open No. Hei 6-11977, a high recording speed is maintained by lowering the speed of an intermediate transfer body when transferring and fixing an image than the speed in other processes during image formation. I have to.

[0006]

As described above, in an image forming apparatus using an electrostatographic process, the process linear velocity is changed in order to change the image resolution at a low cost, or a thick paper or an OHP sheet is used. A device in which the process linear velocity is changed for various types of paper up to thin paper has been proposed and put to practical use.

However, due to such a difference in process linear speed, after all image forming processes have been completed, the stop at which process linear speed the photosensitive member (image carrier) and the intermediate transfer member are stopped. The positions are different, and as a result, it takes a long time to perform image alignment at the time of the next image formation for a full-color image or the like, and there is a problem that it takes time for the first copy. In particular, many models that support various paper types have an intermediate transfer member. In this case, a mark for image alignment is provided at a predetermined position on the intermediate transfer member, and the mark is detected. On the basis of this, a writing signal to the image carrier is turned on to start writing. In the case of such a control method, if the position of the mark at the time of stoppage shifts, the time required to turn on the write signal at the next image formation also shifts accordingly. As a result, at the time of the next image formation, Will be delayed.

A description will be given of an actual measurement example. For example, after forming an image at a process linear velocity of 156 mm / s (resolution 400 dpi) and a process linear velocity of 104 mm / s (resolution 600 dpi), and completing the image forming process, 156 mm / s at the time of the next image forming.
(When the image formation is started at a resolution of 400 dpi), the timing of turning on the image forming motor (drum motor) for rotating and driving the photosensitive member and the intermediate transfer body, and the timing of detecting the mark for aligning the image on the intermediate transfer body. When the time T1 (see FIG. 9) was measured, it stopped at a linear velocity of 156 mm / s: T1 = 210, 208, 2
09 ms Stopped at a linear velocity of 104 mm / s: T1 = 328, 330, 3
It was 28 ms. That is, 118 to 122 at time T1.
There is a difference of about ms, which affects the first copy time required for starting the next image formation.
Here, if the difference of the time T1 is on the order of several tens of ms, it can be said that it is an allowable range. Would.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of obtaining a stable first copy time at the start of the next image formation based on detection of a mark for image alignment even under conditions having a plurality of types of process linear velocities. With the goal.

More specifically, the present invention provides an image forming apparatus capable of obtaining a stable first copy time at the start of the next image formation based on detection of a mark for image alignment while coping with various resolution changes and paper type changes. The purpose is to do.

It is another object of the present invention to provide an image forming apparatus capable of always obtaining the same stable first copy time at the start of the next image formation based on detection of a mark for image alignment even when the process linear velocity is changed. And

[0012]

According to the first aspect of the present invention,
An image is formed by irradiating the image carrier with a writing laser beam in accordance with an image forming process, and the image on the image carrier is temporarily transferred to an intermediate transfer member. A plurality of types of linear velocities A of the image forming process for changing the writing density of the writing laser light in the sub-scanning direction to change the resolution of an image to be formed, A plurality of types of linear velocities B of the transfer process for transferring the image from the intermediate transfer member to the transfer material can be freely combined, and detection of an image alignment mark provided at a predetermined position of the intermediate transfer member allows the image carrier to be moved. Writing timing control means for controlling the writing timing of the writing laser light, and the image carrier according to a process linear velocity at the time of stop after the end of the image forming process and the transfer process And a stop timing control means for changing the stop timing of the drive means for rotating the said intermediate transfer body.

Therefore, under a condition having a plurality of process linear velocities capable of coping with various resolution changes and paper type changes, a stop timing for stopping the driving means for the image carrier or the like according to the process linear speed at the time of the stop. Is changed in consideration of an actual shift amount or the like corresponding to the process linear velocity, so that the stop positional relationship between the image bearing member and the intermediate transfer member can be stabilized. Therefore, a stable first copy time can be maintained at the start of the next image formation based on the detection of the mark for image alignment on the intermediate transfer member.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the stop timing control means includes:
The change control is performed such that the higher the process linear velocity at the time of stop, the earlier the stop timing of the driving means.

Therefore, even when the process linear velocity is changed, the operation of the first aspect can be maintained.

According to a third aspect of the present invention, an image is formed by irradiating an image carrier with a writing laser beam in accordance with an image forming process.
After once transferring the image on the image carrier to an intermediate transfer member,
In an image forming apparatus for transferring an image on the intermediate transfer member onto a transfer material in accordance with a transfer process, the image forming apparatus for changing the writing density of the writing laser light in the sub-scanning direction to change the resolution of the formed image. A plurality of types of linear velocities A of the image forming process and a plurality of types of linear velocities B of the transfer process for transferring from the intermediate transfer body to the transfer material can be freely combined, and an image provided at a predetermined position on the intermediate transfer body Writing timing control means for controlling the writing timing of the writing laser beam to the image carrier by detecting a mark for alignment, and a stopping process for keeping a process linear velocity at a stop after the end of the image forming process and the transfer process Linear velocity control means.

Therefore, by controlling the process linear speed at the time of stop under a condition having a plurality of process linear speeds capable of coping with various resolution changes and paper type changes, an image forming process, a transfer process, etc. Irrespective of the change in the process linear velocity, the stop position relationship between the image bearing member and the intermediate transfer member can be stabilized. Therefore, a stable first copy time can be maintained at the start of the next image formation based on the detection of the mark for image alignment on the intermediate transfer member.

[0018]

FIG. 1 shows a first embodiment of the present invention.
7 will be described with reference to FIG. In the present embodiment, the KC
It is applied to a full-color copying machine using toners of MY (black, cyan, magenta, and yellow). FIG.
1 shows a schematic configuration of the whole, and includes a printer 1, a scanner 2, a paper feeding unit 3, a document feeder 4, and a sorter 5.

Here, a configuration example of a main part of the printer 1 will be described with reference to FIG. First, a drum-shaped photoconductor 10 that is driven to rotate counterclockwise as an image carrier is provided. Around the photoreceptor 10, according to an electrostatographic process, a static elimination lamp 11, a charging charger 12 using a charging scotron charger, a writing optical system 13, an eraser 14, a full-color developing device 15, and an intermediate transfer belt 16 as an intermediate transfer body And a cleaning device 17 are provided in this order.

The writing optical system 13 includes a polygon mirror 18 that deflects and scans a writing laser beam emitted from a semiconductor laser (not shown) modulated according to image data toward the photoconductor 10, and the polygon mirror 18. Is constituted by a polygon motor 19 for rotating the lens at high speed, an fθ lens 20, and the like. The full-color developing device 15 is a black K
And a developing unit 15C for cyan C, a developing unit 15M for magenta M, and a developing unit 15Y for yellow Y are arranged in a cylindrical revolver unit 21 into four equal parts. By rotating the revolver unit 21 by the revolver motor 22 (see FIG. 4), a developing device facing the photoconductor 10 is selected. Also,
When the revolver unit 22 is rotated by the revolver motor 22, the developing sleeve in each of the developing devices is regulated to a position where the developing sleeve does not face the photoconductor 10 by switching means (not shown). Are configured to be able to appropriately take a state where they do not contact each other (non-contact state).

The intermediate transfer belt 16 is formed longer than the peripheral length of the photoconductor 10 (having a length capable of forming at least two A4 size screens simultaneously) and is supported by a plurality of rollers 23 and the like. The rotary motor 10 is driven to rotate by a drum motor 24 (see FIG. 4) as a drive source together with the motor 10. Such an intermediate transfer belt 16 is a member to which an image (toner image) formed on the photoreceptor 10 is once transferred. In the case of full color, a toner image of four colors is transferred and then the toner image is transferred. The image is transferred to the transfer material 25. For this reason, the belt transfer charger 26 is provided on the inner peripheral side facing the photoconductor 10.
Are arranged. Further, the intermediate transfer belt 16 is provided with a paper transfer charger 28 for transferring the toner image on the intermediate transfer belt 16 to the transfer material 25 timed by the registration roller 27, and is provided on the downstream side thereof. A cleaning device 29 is provided at a position upstream of the photoconductor 10.

The intermediate transfer belt 16 is provided with alignment marks 30x and 30y at predetermined positions. The mark 30x is a mark used to align the toner image formed on the photoreceptor 10 on the intermediate transfer belt 16 with the toner image of each color. Roller 27
This mark is used for alignment with the leading end of the transfer material 25 conveyed from the printer. A mark sensor 31 for detecting such marks 30x and 30y is provided at a predetermined position in the intermediate transfer belt 16. 32 is a transferred transfer material 2
5 is a transport belt for transporting the fixing belt 5 to the fixing unit 33 (see FIG. 4).

The printer 1 is mainly controlled by the printer controller 41. As shown in FIG. 3, the printer control unit 41 is provided together with the control units 42, 43, 44, 45, and 46 for each unit such as the scanner 2, and the system control unit 47 performs printing processing, image writing processing, and sheet feeding. The processing, the document transport processing, and the sorting processing are controlled.

FIG. 4 shows an example of the configuration of the printer control unit 41. The printer control unit 41 includes a CPU 51, a ROM 5,
The microcomputer 51 is mainly controlled by a microcomputer including a serial communication controller 54, a write control IC 55, and a laser light source control unit 5 according to a control program stored in a ROM 52 in advance.
6, IO controller 57, main motor 58, drum motor 24, developing motor 59, revolver motor 22, supply motor 60, polygon motor 19, mark sensor 3
1. It controls the revolver home position sensor 61, the fixing unit 33, the power supply unit 62, the electrometer circuit 63, and the toner adhesion amount sensor (so-called P sensor) circuit 64.

The CPU 51 has functions of a relative position detecting means 51a, a mark detection time predicting means 51b, and a time comparing means 51c. As a result, Japanese Patent Application Laid-Open
As shown in Japanese Patent Application Laid-Open No. 185271, the relative position detection means 51a is a relative position between the position of the mark for alignment and the position of the mark sensor 31 for detecting the marks 30x and 30y for alignment shown in FIG. Detect relationships. The mark detection time estimating means 51b calculates the position of the mark detected by the relative position detecting means 51a at the start of image formation and the position of the mark sensor 31 for detecting the marks 30x and 30y. Mark sensor 31
Predicts the time required for detecting the alignment marks 30x and 30y. The time comparing means 51c reduces the time to reach the detection position of the mark sensor 31 for detecting the marks 30x and 30y on the intermediate transfer belt 16 predicted by the mark detection time prediction means 51b and the speed of the intermediate transfer belt 16 to, for example, half speed. The difference from the time until the speed of the intermediate transfer belt 16 stabilizes in that case is obtained. The writing control IC 55 controls exposure of image data via the laser light source control unit 56 and the polygon motor 19. The drum motor 24 rotationally drives the photoconductor 10 and the intermediate transfer belt 16 as described above.

Here, in the present embodiment, in order to change the resolution of an image to be formed, a line of an image forming process for changing the writing density of the writing laser beam on the photosensitive member 10 in the sub-scanning direction. As the speed A, three types of scanning line density, polygon rotation speed, process speed (linear speed A) 400 dpi 24566.9 rpm 156 mm / s 600 dpi 24566.9 rpm 104 mm / s 800 dpi 24566.9 rpm 78 mm / s (half speed) are prepared, and Two types of linear speeds B of a plurality of types of transfer processes for transferring from the transfer belt 16 to the transfer material 25 are prepared: paper type process speed (linear speed B) plain paper 156 mm / s cardboard / OHP 78 mm / s (half speed). (Stored in the ROM 52 or the RAM 53), and these can be freely combined. According to the scanning line density (resolution) on the operation panel and the paper type selection, 3 × 2 = 6 types of image forming modes can be selected.

That is, 400 dpi plain paper mode (A = B = 156 mm / s) 400 dpi thick paper / OHP mode (A = 156 mm / s, B = 78 mm / s) 600 dpi plain paper mode (A = 104 mm / s, B = 156 mm) / S) 600 dpi cardboard / OHP mode (A = 104 mm / s, B = 78 mm / s) 800 dpi plain paper mode (A = 78 mm / s, B = 156 mm / s) 800 dpi cardboard / OHP mode (A = B = 78 mm / s) 6 types can be freely selected.

In the present embodiment, the CPU 5
1 executes the functions of the write timing control means and the stop timing control means.

In such a configuration, a full-color image is converted to 400 dpi cardboard / OHP (A = 156 mm / s, B = 7
The sequence control in the printer control unit 43 in the case of forming in the 8 mm / s mode (however, it is assumed that images for two screens are continuously formed on the intermediate transfer belt 16) is shown in the time chart of FIG. I will explain. When an image forming start command is received, the charge removing lamp 11 and the drum motor 24 are turned on, and an image forming cycle is started. As a result, the photoconductor 10 rotates counterclockwise, and the intermediate transfer belt 16 rotates clockwise. At this time, the linear velocity A of the photoconductor 10 and the intermediate transfer belt 16 is 156 mm / s. Here, when the portion on the photosensitive member 10 that is in contact with the charge removing lamp 11 at the time when the charge removing lamp 11 is turned on reaches the charging position, the charging charger 12 is turned on. When the portion where the charger 12 is in contact with the photoreceptor 10 at the time when the charger 12 is turned on reaches the developing position, the developing bias DC, the developing bias AC, and the developing motor 59 are turned on. Further, when the portion in contact with the developing device 15K, 15C, 15M or 15Y at the time when the developing bias on the photoreceptor 10 is turned on reaches the image transfer position to the intermediate transfer belt 16, the belt transfer charger 26 is turned on. I do. The developing device 15K stopped at the developing position,
The color of 15C, 15M or 15Y is a designated development color (for example,
If the developing color is different from black (K), the developing bias is turned on, and then the revolver unit 21 is rotated to move the developing device of the designated developing color to the developing position.

When the intermediate transfer belt 16 rotates and the mark sensor 31 detects the alignment mark 30x, a scan start command for the first color (black) is transmitted. The electrostatic latent images of the first color (black) for two screens on the photoconductor 10 are continuously developed, and when the transfer to the intermediate transfer belt 16 is completed, the developing device 15C for the second color (for example, cyan C) is moved to the development position. The revolver unit 21 is rotated to come to the position. When the transfer to the intermediate transfer belt 16 is completed, the cleaning device 29 that has been in contact with the intermediate transfer belt 16 is released so that the image on the intermediate transfer belt 16 is not erased. Thereafter, when an interruption due to the detection of the mark 30x by the mark sensor 31 is input again, the scan start command for the second color (cyan C) is transmitted. An untransferred image is superimposed on the intermediate transfer belt 16 for two screens in the same manner as the first color (black). Then, the third color (for example, magenta M)
The revolver unit 21 is rotated so that the developing device 15M of the second position comes to the developing position. Images for two screens of the third color (magenta M) and the fourth color (yellow Y) are similarly developed, and an untransferred image is superimposed on the intermediate transfer belt 16. In this manner, the writing timing of the writing laser to the photoconductor 10 is controlled by the writing timing control means based on the detection of the mark 30x.

On the other hand, when the image formation is started, the transfer material (thick paper) 25 has begun to be fed from the paper feed cassette in the paper feed unit 3. When the leading end of the toner image on the intermediate transfer belt 16 approaches the paper transfer charger 28 for transferring the image on the intermediate transfer belt 16 to the transfer material 25, the leading end of the transfer material 25 coincides with the leading end of the toner image. Thus, the registration of the transfer material 25 and the toner image is performed. This registration is performed based on the detection of the alignment mark 30y by the mark sensor 31. At this time, the linear velocity B of the photoconductor 10 and the intermediate transfer belt 16 becomes 78 mm after the transfer to the intermediate transfer belt 16 is completed. / S. When the linear velocity B is switched, the photosensitive member 10
Of the developing device 15 of the full-color developing device 15
K, 15C, 15M, and 15Y are also restricted to the non-contact position. When the transfer material 25 passes through the paper transfer charger 28 connected to the positive potential power supply while being superimposed on the toner image on the intermediate transfer belt 16 in this manner, the transfer material 25 is charged with a positive charge by the corona discharge current. Then, the toner image is transferred. The charge on the transfer material 25 is transferred to a paper transfer charger 28.
Is removed when passing through the position of a charge removal core (not shown) provided slightly downstream of the. Transfer material 2 with toner image
5 is sent to the fixing unit 33 by the conveyor belt 32. The fixing unit 33 heats and presses the transfer material 25 to fix the toner image on the transfer material 25. Fixed transfer material 2
5 is discharged outside. In the transfer process including the series of paper transfer and fixing, the linear velocity B is set to a low speed of 78 mm / s. Therefore, even if the transfer material 25 is a thick paper, the fixing efficiency is not deteriorated, and the transfer material 25 is excellent on the thick paper. An image of a high quality can be formed. Further, since the developer is not in contact with the photoconductor 10 when the linear velocity is changed, a high-quality image free of abnormal images such as background contamination and carrier adhesion can be obtained.

When all the images have been transferred to the transfer material 25, the process proceeds to an end sequence. That is, when the belt transfer charger 26 is turned off and the portion of the photoconductor 10 that is in contact with the belt transfer charger 26 when the belt transfer charger 26 is turned off reaches the position of the charger 12, the charger 12 is turned off. To Further, the developing bias and the developing motor 59 are turned off when the portion in contact with the charger 12 at the time when the charging charger 12 on the photoconductor 10 is turned off reaches the developing position. From this point, a standby state for mark detection by the mark sensor 31 attached to the intermediate transfer belt 16 is established. After the detection of the mark 30x, the drum motor 24 is turned on until the mark 30x advances to a predetermined position. The discharge lamp 11 is turned off simultaneously with the turning off.

Next, a case where a full-color image is formed in a 600 dpi plain paper mode (A = 104 mm / s, B = 156 mm / s) mode (however, an image for two screens is continuously formed on the intermediate transfer belt 16) Will be described with reference to a time chart shown in FIG. When an image formation start command is received, the static elimination lamp 11 and the drum motor 24 are turned on,
The image forming cycle starts. Thereby, the photoconductor 10
Rotates counterclockwise, and the intermediate transfer belt 16 rotates clockwise. At this time, the linear velocity A of the photoconductor 10 and the intermediate transfer belt 16 is 104 mm / s. Here, when the portion on the photosensitive member 10 that is in contact with the charge removing lamp 11 at the time when the charge removing lamp 11 is turned on reaches the charging position, the charging charger 12 is turned on. When the portion of the photoreceptor 10 that was in contact with the charger 12 when the charger 12 was turned on reaches the developing position, the developing bias DC
And the developing bias AC and the developing motor 59 are turned on.
Further, when the portion in contact with the developing device 15K, 15C, 15M or 15Y at the time when the developing bias on the photoreceptor 10 is turned on reaches the image transfer position to the intermediate transfer belt 16, the belt transfer charger 26 is turned on. I do. The developing device 15K, 15C, 15M, or 15 stopped at the developing position.
If the Y color is different from the designated developing color (for example, black K), after turning on the developing bias, the revolver unit 21 is rotated to move the developing device of the designated developing color to the developing position.

When the intermediate transfer belt 16 rotates and the mark sensor 31 detects the alignment mark 30x, a scan start command for the first color (black) is transmitted. The electrostatic latent images of the first color (black) for two screens on the photoconductor 10 are continuously developed, and when the transfer to the intermediate transfer belt 16 is completed, the developing device 15C for the second color (for example, cyan C) is moved to the development position. The revolver unit 21 is rotated to come to the position. When the transfer to the intermediate transfer belt 16 is completed, the cleaning device 29 that has been in contact with the intermediate transfer belt 16 is released so that the image on the intermediate transfer belt 16 is not erased. Thereafter, when an interruption due to the detection of the mark 30x by the mark sensor 31 is input again, the scan start command for the second color (cyan C) is transmitted. An untransferred image is superimposed on the intermediate transfer belt 16 for two screens in the same manner as the first color (black). Then, the third color (for example, magenta M)
The revolver unit 21 is rotated so that the developing device 15M of the second position comes to the developing position. Images for two screens of the third color (magenta M) and the fourth color (yellow Y) are similarly developed, and an untransferred image is superimposed on the intermediate transfer belt 16. In this manner, the writing timing of the writing laser to the photoconductor 10 is controlled by the writing timing control means based on the detection of the mark 30x.

On the other hand, when the image formation is started, the transfer material (plain paper) 25 has begun to be fed from the paper feed cassette in the paper feed unit 3. When the leading end of the toner image on the intermediate transfer belt 16 approaches the paper transfer charger 28 for transferring the image on the intermediate transfer belt 16 to the transfer material 25, the leading end of the transfer material 25 coincides with the leading end of the toner image. Thus, the registration of the transfer material 25 and the toner image is performed. The registration is performed based on the detection of the alignment mark 30y by the mark sensor 31. At this time, the linear velocity B of the photoconductor 10 and the intermediate transfer belt 16 is 156 mm after the transfer to the intermediate transfer belt 16 is completed. / S. When the linear velocity B is switched, any of the developing units 15K, 15C, 15M, and 15Y of the full-color developing device 15 is regulated to the non-contact position with respect to the photoconductor 10. Thus, the transfer material 25 is transferred to the intermediate transfer belt 16.
When passing through the paper transfer charger 28 connected to the positive potential power supply while being superposed on the upper toner image, the transfer material 25 is charged with a positive charge by the corona discharge current, and the toner image is transferred. The charge on the transfer material 25 is transferred to a paper transfer charger 28.
Is removed when passing through the position of a charge removal core (not shown) provided slightly downstream of the. Transfer material 2 with toner image
5 is sent to the fixing unit 33 by the conveyor belt 32. The fixing unit 33 heats and presses the transfer material 25 to fix the toner image on the transfer material 25. Fixed transfer material 2
5 is discharged outside. In the transfer process including the series of paper transfer and fixing, the linear speed B is increased to 156 mm / s.
Although the processing up to image transfer to 6 is high resolution and slow, the processing speed of transfer from the intermediate transfer belt 16 to the transfer material 25 is increased, and overall printing efficiency can be improved. That is, the printing efficiency can be improved while utilizing the high resolution. When the linear velocity is changed, the developer is
Since no contact is made, a high quality image free of abnormal images such as background contamination and carrier adhesion can be obtained.

When all the images have been transferred to the transfer material 25, the process proceeds to an end sequence. That is, when the belt transfer charger 26 is turned off and the portion of the photoconductor 10 that is in contact with the belt transfer charger 26 when the belt transfer charger 26 is turned off reaches the position of the charger 12, the charger 12 is turned off. To Further, the developing bias and the developing motor 59 are turned off when the portion in contact with the charger 12 at the time when the charging charger 12 on the photoconductor 10 is turned off reaches the developing position. From this point, a standby state for mark detection by the mark sensor 31 attached to the intermediate transfer belt 16 is established. After the detection of the mark 30x, the drum motor 24 is turned on until the mark 30x advances to a predetermined position. The discharge lamp 11 is turned off simultaneously with the turning off.

As described above, under the condition that there are a plurality of types of process linear velocities capable of coping with various resolution changes and paper type changes, after the image forming process and the transfer process are completed, the stop timing controlled by the stop timing control means is controlled. Sequence (end sequence) control will be described with reference to FIG.
In the present embodiment, the stop timing of the drum motor 24 that drives the photoconductor 10 and the intermediate transfer belt 16 to rotate is basically changed according to the process linear velocity at the time of stop. More specifically, the change control is performed so that the stop timing of the drum motor 24 is earlier as the process linear velocity at the time of stop is higher.

Now, in the configuration of the printer 1 as shown in FIG. 2, the circumferential length DL of the drum-shaped photosensitive member 10 = 282.
74 mm, circumference BL of the intermediate transfer belt 16 = 565.49
mm. Further, the position of the charge removing lamp 11 is set as a reference position (origin), the length L1 from the reference position to the charging charger 12 is 23.67 mm, the length L4 from the reference position to the developing position is 86.50 mm, and the belt is from the reference position. Length L7 = 179.85 mm to the entrance of the transfer charger 26, and length L9 = 22 from the reference position to the paper transfer charger 28
5.87 mm.

FIG. 7A shows that the process linear velocity at the time of stop is 1
FIG. 7B shows an example of an end sequence in the case of 56 mm / s (= 400 dpi).
An example of an end sequence in the case of mm / s (= 600 dpi) is shown. After both detect the mark 30x,
The charging charger 12 is turned off at a timing advanced by 277 mm, and the developing bias DC and the developing motor 59 are turned off at a timing advanced by 435 mm. The off timing (time to turn off) differs depending on a difference in process linear velocity. (Basically, the time in FIG. 7B having the lower linear velocity is set to 1.5 times as long). The off timing of the belt transfer charger 26 and the paper transfer charger 28 is set in the same manner.
Further, regarding the off-timing of the drum motor 24 that drives the photoconductor 10 and the intermediate transfer belt 16 to rotate,
In the case of the linear velocity of 156 mm / s shown in FIG. 7A, the timing is that 365 ms has elapsed after the paper transfer charger 28 was turned off (corresponding to the length of DL-L9), but FIG.
In the case of a linear velocity of 104 mm / s, the ratio of the linear velocity is 1.5 times, that is, 365 × 1.5 = 547.5 ms
As described in the example of the actual measurement value in FIG. 9, the average value of the actual deviation 120 ms (converted to 400 dpi) → 180 ms (6
547.5 + 1
The timing is set to 80 = 727.5 ms. That is, in the case of the example of the actually measured value described with reference to FIG. 9, the linear velocity is reduced by 10 compared with the case where the linear velocity is stopped at 156 mm / s.
When stopped at 4 mm / s, the linear velocity is 156 at the stop position.
Since there is a delay (actual deviation) of 118 to 122 ms in average of 120 ms in terms of mm / s, when stopping at a linear velocity of 104 mm / s, this deviation is converted to a linear velocity of 104 mm / s and the extra time is sent. In this case, the stop timing is changed so as to stop. Such actual deviation is
Optimization is necessary because it varies with the load on the machine (due to the moment of inertia).

As exemplified in FIGS. 7A and 7B,
The stop timing control means changes and controls the stop timing of the drum motor 24 in accordance with the process linear velocity at the time of stop. The stop position relationship can always be stabilized. Accordingly, a stable first copy time can be maintained at the start of the next image formation based on the detection of the image alignment mark 30x on the intermediate transfer belt 16.

A second embodiment of the present invention will be described with reference to FIG. The same portions as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, instead of the stop timing control means, the CP
By adding the function of the stop process linear velocity control means executed by U51, the process linear velocity at the time of stop is always kept constant.

In this embodiment, the process linear velocity at the time of stoppage is fixed at 156 mm / s (= 400 dpi) regardless of the process linear velocity at the time of the image forming process or the transfer process. Therefore, when the process linear speed during the transfer process is 156 mm / s (= 400 dpi), the stop processing is performed at the process linear speed of 156 mm / s (= 400 dpi) even in the termination sequence at the time of the stop. That is, it is the same as the case shown in FIG.

On the other hand, when the process linear velocity during the transfer process is 104 mm / s (= 600 dpi), FIG.
As shown in the figure, the process linear velocity was 156 mm / s (= 40
0dpi), and then the same stop processing as in the case shown in FIG. 7A is performed.

Therefore, according to the present embodiment, under the condition that there are a plurality of types of process linear velocities that can cope with various resolution changes and paper type changes, the process linear speed at the time of stop is controlled to be constant. The stop position relationship between the photoreceptor 10 and the intermediate transfer belt 16 can always be stabilized irrespective of a change in a process linear velocity such as an image forming process or a transfer process before that. Therefore, the intermediate transfer belt 16
A stable first copy time can be maintained at the start of the next image formation based on the detection of the upper image alignment mark 30x.

[0045]

According to the first aspect of the present invention, under the condition that there are a plurality of types of process linear velocities capable of coping with various resolution changes and paper type changes, an image is carried in accordance with the process linear speed at the time of stoppage. Since the stop timing for stopping the driving means for the body or the like is changed by the stop timing control means in consideration of the actual deviation or the like according to the process linear velocity, the stop position relation between the image carrier and the intermediate transfer body Therefore, a stable first copy time can be maintained at the start of the next image formation based on the detection of the mark for image alignment on the intermediate transfer body.

According to the second aspect of the present invention, in the image forming apparatus according to the first aspect, the stop timing control means controls the change so that the stop timing of the drive means becomes earlier as the process linear velocity at the time of stop becomes faster. Therefore, even when the process linear velocity is changed, the effect of the first aspect of the present invention can be reliably maintained.

According to the third aspect of the present invention, under the condition that there are a plurality of types of process linear velocities capable of coping with various resolution changes and paper type changes, the process linear speed at the time of the stop is stopped. , The stop position relationship between the image carrier and the intermediate transfer member can be stabilized regardless of the change in the process linear velocity such as the image forming process and the transfer process. A stable first copy time can be maintained at the start of the next image formation based on detection of a mark for image alignment on the body.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a basic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a configuration of a printer unit.

FIG. 3 is a schematic block diagram illustrating a configuration of an entire control system.

FIG. 4 is a block diagram illustrating a configuration of a printer control unit.

FIG. 5 is a time chart showing sequence control in a 400 dpi thick paper / OHP mode.

FIG. 6 is a time chart showing sequence control in a 600 dpi plain paper mode.

FIG. 7 is a time chart showing an end sequence control when the process linear speeds are different.

FIG. 8 is a time chart illustrating an end sequence control according to the second embodiment of this invention.

FIG. 9 is a time chart showing a deviation time T1 between the ON timing of the image forming motor and the mark detection timing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image carrier 16 Intermediate transfer body 25 Transfer material 30 Mark

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/113 G03G 21/00 372 1/29 H04N 1/04 104A F-term (Reference) 2H027 DA38 DA50 EA20 EB04 EC06 EC20 ED02 ED08 ED16 ED24 EE02 EE04 EE07 EF09 2H030 AA01 AA06 AD12 AD17 BB02 BB16 BB24 BB42 BB56 2H032 AA02 AA05 BA09 CA01 CA13 5C072 AA03 HA02 HA09 HA13 HB11 QA14 BB14 BB04 BB04

Claims (3)

[Claims] An image is formed by irradiating an image carrier with a writing laser beam in accordance with an image forming process, and the image on the image carrier is temporarily transferred to an intermediate transfer member. In an image forming apparatus for transferring onto a transfer material in accordance with a transfer process, a plurality of lines of the image forming process for changing a writing density of the writing laser light in a sub-scanning direction to change a resolution of an image to be formed. Speed A and a plurality of types of linear velocities B of the transfer process for transferring from the intermediate transfer body to the transfer material can be freely combined, and by detecting an image alignment mark provided at a predetermined position on the intermediate transfer body, Writing timing control means for controlling the writing timing of the writing laser light to the image carrier, and according to the process linear velocity at the time of stop after the end of the image forming process and the transfer process And a stop timing control means for changing a stop timing of a driving means for rotatingly driving the image carrier and the intermediate transfer body. 2. The image forming apparatus according to claim 1, wherein the stop timing control means controls the change so that the stop timing of the drive means is earlier as the process linear velocity at the time of stop is faster. 3. An image is formed by irradiating a writing laser beam to an image carrier according to an image forming process, and once transferring the image on the image carrier to an intermediate transfer member, the image on the intermediate transfer member is transferred to the intermediate transfer member. In an image forming apparatus for transferring onto a transfer material in accordance with a transfer process, a plurality of lines of the image forming process for changing a writing density of the writing laser light in a sub-scanning direction to change a resolution of an image to be formed. Speed A and a plurality of types of linear velocities B of the transfer process for transferring from the intermediate transfer body to the transfer material can be freely combined, and by detecting an image alignment mark provided at a predetermined position on the intermediate transfer body, Writing timing control means for controlling the writing timing of the writing laser light to the image carrier; and a constant process linear velocity at the time of stop after the end of the image forming process and the transfer process. And a stop process linear velocity control unit.