JP2003228265A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus which allows the life of a photoreceptor to be prolonged in comparison to a conventional one by adequately reducing deterioration of the photoreceptor even in the case of both-sided printing where vertical ruled lines that are the same in position on an original image are printed on the fronts and backs of transfer materials which are supplied consecutively. <P>SOLUTION: For printing on the surface of transfer paper supplied as a first sheet, a scanning start potion for data to be exposed is set to R1. For printing on the back of the transfer paper, the scanning start position is shifted by a predetermined number of dots in the main scanning direction M so as not overlap the main scanning direction used for an electrostatic latent image along the vertical ruled line, thereby setting a position R2. When printing is carried out on the front and back of transfer paper thereafter, the scanning start position is shifted to a position R3, a position R4... in the main scanning direction M. Also, while the scanning start position for printing on the surface is fixed at the position R1, only the scanning position for printing on the back may be moved to the position R2, position R3... each time transfer paper is supplied. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus for printing print data such as characters and ruled lines on both sides of a transfer material.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus,
Ruled lines (hereinafter referred to as vertical ruled lines) on which an electrostatic latent image is formed may be printed along the sub-scanning direction of the photoconductor. For example, when printing a form sheet, there is an original document that contains ruled lines in the original image, and if this is output to multiple transfer materials as print data, the vertical ruled lines of those ruled lines are applied to any transfer material. It may always be printed at the same position. In the reversal development method, the exposed part becomes a visible image by development,
During printing, the image exposure position on the photoconductor where the electrostatic latent image corresponding to the vertical ruled line is written is the same position as seen in the main scanning direction of the photoconductor, that is, a fixed distance from one axial end of the photoconductor in the main scanning direction. The image exposure light of vertical ruled lines is repeatedly applied to the image exposure position for each transfer material through printing on a plurality of transfer materials. For this reason,
The degree of deterioration of this part of the photoconductor was significantly larger than that of the other parts such as poor recovery of the charging potential and poor development, and the life of the photoconductor was extremely shortened.

Japanese Laid-Open Patent Publication No. 58-127957 discloses a photoconductor at a predetermined interval for repeated printing using image exposure positions fixed at the same position in the main scanning direction of the photoconductor. The image exposure start position of the photoconductor is changed in the main scanning direction for each recording paper by moving the photoconductor in the axial direction by the moving mechanism or by the operator manually switching the print start position every predetermined period. A method for preventing the occurrence of image problems is disclosed.

Further, Japanese Laid-Open Patent Publication No. 58-216263 also discloses a device for changing the image writing start position with respect to the photoconductor along the axial direction of the photoconductor. In this case, by changing the image writing time with the delay time adjuster, the image writing position is arbitrarily changed in the axial direction of the photoconductor, and the paper feeding position is variable corresponding to the image writing position. By providing the above, it is possible to prevent partial performance deterioration of the photoconductor without displacing the photoconductor.

Further, in Japanese Patent Laid-Open No. 63-305370, a writing position of data in a bit map memory is moved in a predetermined direction in a printing direction according to the number of prints or a numerical value corresponding to the number of prints to always form a high quality image. We are trying to maintain

[0006]

In the image forming apparatus, the first surface (hereinafter, referred to as "front surface") which is one surface of each of the plurality of transfer materials continuously supplied. )), And before the next transfer material is supplied, the other surface is the second surface (hereinafter referred to as the back surface).
Some printers perform double-sided printing. Moreover, in this double-sided printing, print data including image data of vertical ruled lines at the same position on the original image may be printed on both the front surface and the back surface. However, JP-A-58-127957, JP-A-58-216263, and JP-A-63-3053
Japanese Patent Laid-Open No. 70-70 does not describe the change of the image exposure position when the print data including the image data of the vertical ruled lines as described above is printed on both sides. Therefore, in such a conventional image forming apparatus, In the case of performing double-sided printing as described above, it is not possible to preferably avoid the problem that the life of the photoconductor is particularly shortened due to the presence of backside printing. That is, the electrostatic latent image of the vertical ruled lines is formed at the same position on the photoconductor as viewed in the main scanning direction during the back surface printing which is repeatedly performed in a short cycle, and the vertical ruled line static is formed by continuous front surface printing and back surface printing. When the latent image is formed at the same position as described above, the life of the photoconductor becomes particularly short.

The details are as follows. In double-sided printing, in which the surface of the transfer material is printed first and then the back surface of the transfer material, in the double-sided printing, after the surface printing was performed on each transfer material, the transfer material once passed through the fixing device, and the moisture of the transfer material was removed to some extent. It is then used for backside printing. Therefore, the electrical resistance of the transfer material during backside printing increases accordingly, making the transfer voltage during backside printing higher than the transfer voltage during frontside printing, or the transfer current during backside printing to the transfer current during frontside printing. However, the back side printing is likely to damage the photoconductor. On the other hand, with only one-sided printing, the transfer voltage is low or the transfer current is small, so even if electrostatic latent images of vertical ruled lines are repeatedly formed at the same position on the photoconductor in the main scanning direction at short intervals, Damage to the body is unlikely.

Therefore, in single-sided printing, not only the damage due to transfer is small as described above, but also the number of exposures is smaller than that in double-sided printing as described above for the same number of transfer materials, so damage due to exposure is also small. The body does not deteriorate much. However, in order to print vertical ruled lines on the front and back surfaces of a plurality of transfer materials as described above, in the case where electrostatic latent images of vertical ruled lines are repeatedly formed at the same position on the photoconductor in the main scanning direction, , The damage due to the transfer at the time of the back side printing is greatly damaged by the multiple exposures given during the front side printing and the back side printing, and the deterioration of the surface on which the electrostatic latent image is formed, which leads to the generation of image defects, is likely to proceed. , The life of the photoconductor becomes particularly short.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is a vertical ruled line having the same position on an original image for a plurality of transfer materials continuously supplied. An object of the present invention is to provide an electrophotographic image forming apparatus capable of satisfactorily suppressing deterioration of the photoconductor and extending the life of the photoconductor more than before even when performing double-sided printing for printing on the front surface and the back surface. .

[0010]

In order to solve the above-mentioned problems, the image forming apparatus of the present invention uses one of the above-mentioned transfer materials for each transfer material supplied so that the developed image on the image carrier is transferred. Image forming apparatus of double-sided printing capable of performing printing on the second surface, which is the other surface, before printing the next transfer material, after printing on the first surface, which is the second surface In the sub-scanning direction of the photoconductor at the same position on the original image on the first surface and the second surface of the plurality of transfer materials continuously supplied by the double-sided printing. When printing the print data of the original image including the image data of the vertical ruled lines that are the ruled lines on which the electrostatic latent image is formed, the scanning of the exposure of the print data with respect to the main scanning direction of the photoconductor is performed. When printing on the second surface of all the above transfer materials, the start position The formation position of the electrostatic latent image of the vertical ruled line in the main scanning direction overlaps with the formation position of the electrostatic latent image of the vertical ruled line in the main scanning direction immediately before printing on the first surface. Control so that the formation position of the electrostatic latent image of the vertical ruled line seen in the main scanning direction during printing on the first surface and the second surface of the transfer material supplied as the second and subsequent sheets. A scanning start position control means is provided so as not to overlap with the formation position of the electrostatic latent image of the vertical ruled line when viewed on the main scanning direction at the time of printing on the second surface of the transfer material supplied immediately before. It is characterized by

According to the above invention, the positions on the original image are the same when printing on the first surface (front surface) and the second surface (back surface) of a plurality of transfer materials that are continuously supplied. When an electrostatic latent image of vertical ruled lines, which is a ruled line on which an electrostatic latent image is formed along the sub-scanning direction, is formed on the photoconductor, the following is performed by the control of the scanning start position control means.

That is, at the time of printing on the second surface of all the transfer materials, the formation position of the electrostatic latent image of the vertical ruled lines seen in the main scanning direction is the static electricity of the vertical ruled lines at the time of printing on the first surface immediately before. The scanning start position of the exposure as viewed in the main scanning direction is controlled so as not to overlap the formation position of the latent image as viewed in the main scanning direction. Furthermore, 2
For the transfer material supplied after the first sheet, the transfer material supplied immediately before the formation position of the electrostatic latent image of the vertical ruled line in the main scanning direction when printing on the first surface and the second surface. The scanning start position is controlled so as not to overlap with the formation position of the electrostatic latent image of the vertical ruled line in the main scanning direction during printing on the second surface of the.

Therefore, the exposure for the electrostatic latent image of the vertical ruled line may be continuously performed on the same partial peripheral surface of the photoconductor by the printing on the first surface and the printing on the second surface which are arranged in front and back. Not with
There is no possibility that the electrostatic latent image of the vertical ruled line is continuously exposed on the same partial peripheral surface of the photoconductor by printing on the second surface of the two transfer materials supplied before and after. As a result, the frequency of exposure performed through double-sided printing on the same peripheral surface of the photoconductor is reduced, and damage due to exposure is reduced. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the second surface, the damage due to the exposure is not so much, so that the peripheral surface is deteriorated which causes an image defect. Is suppressed, and it is possible to favorably prevent the life of the photoconductor from becoming particularly short.

As described above, even when performing double-sided printing in which vertical ruled lines having the same position on the original image are printed on the front surface and the back surface of a plurality of transfer materials that are continuously supplied, It is possible to provide an electrophotographic image forming apparatus capable of properly suppressing deterioration and extending the life of the photoconductor as compared with the conventional case.

In order to solve the above-mentioned problems, the image forming apparatus of the present invention has one surface of the transfer material for each transfer material supplied so that the developed image on the image carrier is transferred. In the electrophotographic image forming apparatus capable of double-sided printing, in which after printing on the first surface, printing on the second surface, which is the other surface, is performed before the next transfer material is supplied, the double-sided printing is performed. By printing, electrostatic latent images are formed on the first surface and the second surface of the plurality of transfer materials that are continuously supplied at the same position on the original image and along the sub-scanning direction of the photoconductor. When printing the print data of the original image that includes the image data of the vertical ruled line that is the ruled line in which is formed, the scanning start position of the exposure as seen in the main scanning direction of the photoconductor with respect to the print data, Transfer of each of the above when printing on the first surface of all the transfer materials Controlled to be identical to,
At the time of printing on the second surface of all the transfer materials, the formation position of the electrostatic latent image of the vertical ruled line when viewed in the main scanning direction is the first position.
The electrostatic latent image of the vertical ruled line during printing on the surface is controlled so as not to overlap with the formation position viewed in the main scanning direction, and the transfer material supplied as the second and subsequent sheets is transferred to the second surface. The main position of the electrostatic latent image of the vertical ruled line at the time of printing on the second surface of the transfer material supplied immediately before the formation position of the electrostatic latent image of the vertical ruled line at the time of printing. It is characterized in that it is provided with a scanning start position control means for controlling so as not to overlap with the formation position viewed in the scanning direction.

According to the above invention, the positions on the original image are the same when printing on the first surface (front surface) and the second surface (back surface) of a plurality of transfer materials that are continuously supplied. When an electrostatic latent image of vertical ruled lines, which is a ruled line on which an electrostatic latent image is formed along the sub-scanning direction, is formed on the photoconductor, the following is performed by the control of the scanning start position control means.

That is, at the time of printing on the first surface of all the transfer materials, control is performed so that the scanning start position of the exposure is the same when the electrostatic latent images of the vertical ruled lines are viewed in the main scanning direction with respect to each transfer material. To be done. Further, when printing on the second surface of all the transfer materials, the formation position of the electrostatic latent image of the vertical ruled lines seen in the main scanning direction is the main scanning of the electrostatic latent image of the vertical ruled lines when printing on the first surface. The scanning start position is controlled so as not to overlap the formation position seen in the direction. Furthermore, the second transfer material supplied as the second and subsequent sheets
The main scanning direction of the electrostatic latent image of the vertical ruled line at the time of printing on the second surface of the transfer material supplied immediately before the formation position of the electrostatic latent image of the vertical ruled line when printing on the second surface The scanning start position is controlled so as not to overlap the formation position seen in FIG.

Therefore, the exposure for the electrostatic latent image of the vertical ruled line may be continuously performed on the same partial peripheral surface of the photosensitive member by the printing on the first surface and the printing on the second surface which are arranged in front and back. Not with
There is no possibility that the electrostatic latent image of the vertical ruled line is continuously exposed on the same partial peripheral surface of the photoconductor by printing on the second surface of the two transfer materials supplied before and after. As a result, the frequency of exposure performed through double-sided printing on the same peripheral surface of the photoconductor is reduced, and damage due to exposure is reduced. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the second surface, the damage applied by the exposure is small, so that the deterioration of the peripheral surface leading to the occurrence of an image defect does not occur. It is possible to favorably prevent the life of the photoconductor from being shortened.

As described above, even when performing double-sided printing in which vertical ruled lines having the same position on the original image are printed on the front surface and the back surface of a plurality of transfer materials that are continuously supplied, It is possible to provide an electrophotographic image forming apparatus capable of properly suppressing deterioration and extending the life of the photoconductor as compared with the conventional case.

Further, in order to solve the above-mentioned problems, the image forming apparatus of the present invention, when printing the print data including the image data of the vertical ruled lines, when printing on the second surface, It is provided with an exposure intensity control unit for controlling the exposure intensity to be lower than that in the case of printing the print data in which only the image data of ruled lines other than the vertical ruled lines are included as the image data of ruled lines. I am trying.

According to the above invention, when the vertical ruled lines are printed as in the above invention, the exposure intensity of the exposure means at the time of printing on the second surface is used as the ruled lines by the control of the exposure intensity control means. The control is performed so that it is lower than when only the ruled lines other than the vertical ruled lines are printed. Therefore, since the exposure intensity at the time of printing on the second surface is small, damage due to exposure is particularly small. As a result, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the second surface, the damage applied by the exposure is very small, so that the peripheral surface leading to the occurrence of an image defect is generated. Is particularly suppressed,
It is possible to very satisfactorily avoid shortening the life of the photoconductor.

Further, in order to solve the above-mentioned problems, the image forming apparatus of the present invention is characterized in that the scanning start position control means controls the scanning start position to move in units of exposure dots.

According to the above invention, the scanning start position can be moved by a very small amount in units of the exposure dot under the control of the scanning start position control means. Therefore, it is possible to avoid the size increase of the apparatus due to the photosensitive drum being considerably enlarged in the main scanning direction or the photosensitive drum being moved, and the photosensitive drum can be moved or the transfer material supply position can be changed. There is no need for difficult control such as moving.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the image forming apparatus of the present invention will be described below with reference to FIGS.

FIG. 3 shows the configuration of the main part of the printing-related portion of the image forming apparatus according to this embodiment. The image forming apparatus is an electrophotographic image forming apparatus, and includes a printing unit 21 and a transfer paper conveyance unit 41.

The printing unit 21 includes a photosensitive drum 1, a charger 2, an exposure unit 3, a developing unit 4, a pre-transfer exposure unit 5, a transfer unit 6,
A cleaning unit 7, an erasing lamp 8 and a fixing device 9 are provided.

The photosensitive drum 1 is an image carrier having a photoconductive layer serving as a photosensitive member provided on a cylindrical conductive substrate, and is rotatably supported in the direction of arrow N in the figure. The charger 2 is a charging unit that initially charges the photoconductor of the photoconductor drum 1 for image formation. Here, the charger 2 is a well-known scorotron charger, and the photoconductor of the photoconductor drum 1 has a predetermined potential (-
It is uniformly charged to about 600 to -650V). Exposure unit 3
Is an exposing unit that forms an electrostatic latent image by exposing the photoconductor charged by the charger 2 according to print data while scanning along the main scanning direction of the photoconductor, and in response to an image information signal E described later. The modulated laser light is applied to the photoconductor charged by the charger 2 to form an electrostatic latent image on the photoconductor. The exposure unit 3 irradiates a laser beam emitted from the semiconductor laser 31 to a portion of the electrostatic latent image visualized by the developing device 4 through a rotating polygon mirror 33, a mirror 35, or the like to expose the laser beam. Perform scanning exposure on the body. The detailed configuration of the exposure unit 3 will be described later.

The developing device 4 is a developing means for developing the electrostatic latent image formed by the exposure section 3 so that the exposed portion becomes a visible image, and contains toner. By performing reversal development to form a toner image as a development image on the photoconductor, the electrostatic latent image is developed so that the exposed portion becomes a visible image. The pre-transfer exposure unit 5 exposes the surface of the photoconductor bearing the toner image prior to the step of transferring the toner image onto the transfer paper P by the transfer unit 6. The transfer unit 6 is a transfer unit that electrostatically transfers the developed image formed by the developing unit 4 to the supplied transfer material. Here, for example, it is a contact type transfer device using a constant current control system or a constant voltage control system, and is on a transfer paper P as a transfer material that is fed by the transfer paper transport unit 41 along the transport path of the transport unit 12. , The toner image after being exposed by the pre-transfer exposure unit 5 is electrostatically transferred. The fixing device 9 transfers the toner image by the transfer device 6, separates the toner image from the photoconductor, and transfers the transfer paper P.
It is a fixing unit that forms a print image of print data by permanently fixing a toner image using at least heating such as heating and pressing.

The cleaning unit 7 removes the toner remaining on the surface of the photoconductor of the photoconductor drum 1 which continues to rotate after the transfer process. The erasing lamp 8 erases the residual charges on the photoconductor after the residual toner is removed by the cleaning unit 7, and returns the photoconductor to the initial state for the next image formation.

Since the printing section 21 is provided,
The image forming apparatus prints the print data represented by the image information signal E on the transfer material P by performing at least initial charging, exposure, development, transfer, and fixing while rotating the photosensitive drum 1. .

The transfer paper transport unit 41 includes a paper feed unit 11,
The transport unit 12, the switchback transport unit 13, and the paper discharge unit 14 are provided. The paper feed unit 11 includes a paper feed tray that stores the transfer paper P and various rollers that perform a paper feed operation.
The transfer paper P has a reduced water content due to the heating in the fixing process by the fixing device 9. The transport unit 12 transports the transfer paper P fed from the paper feed unit 11 and the transfer paper P returned by the switchback transport unit 13 to the transfer unit 6 and the fixing unit 9 and various rollers. Is equipped with. The switchback transport unit 13 reverses the front and back of the transfer paper P that has undergone the fixing process by the fixing device 9 and transports the transfer paper P so as to return the transfer paper P to the transport upstream side of the transfer unit 6. A back mechanism, a switchback transport path, and various rollers for transporting the transfer paper P are provided. Paper output unit 14
Is for ejecting the transfer paper P on which printing has been completed after the fixing process by the fixing device 9 is completed.
It is provided with a paper discharge tray for receiving the paper and various rollers for carrying out the paper discharge operation.

Since the transfer paper transport unit 41 is provided with the switchback transport unit 13, the image forming apparatus can perform not only single-sided printing on the transfer paper P but also printing on the front surface (first surface) and back surface (first surface). Double-sided printing with printing on the second surface) can be performed. At the time of double-sided printing, after finishing the fixing process of the surface of the transfer sheet P, the transfer sheet P is conveyed to the conveying section 12 by the switchback conveying section 13 before the next transfer sheet P is fed.
The transfer device 6 performs a transfer process on the back surface. Then, the toner image transferred on the back surface is fixed by the fixing device 9, and the transfer paper P is discharged by the paper discharge unit 14, and the printing process is completed.

Next, FIG. 4 shows a detailed structure of the exposure section 3 of the printing section 21. The exposure unit 3 includes a semiconductor laser 31, a light modulator 32, a polygon mirror 33, an imaging lens 34, a mirror 35, a light detection mirror 36, a light detection sensor 37,
And a delay circuit 38.

The semiconductor laser 31 is a light source for exposure,
Emit laser light. The light modulator 32 is a controller that controls the irradiation of the photoconductor with the laser light emitted from the semiconductor laser 31 in accordance with an image information signal E including print data and input from the outside. Polygon mirror 33
Scans the photoconductor with the laser light modulated by the optical modulator 32 in the main scanning direction (hereinafter, M is omitted) indicated by an arrow M in the figure, which is a direction along the rotation axis direction of the photoconductor drum 1. It is a rotating polygonal mirror that reflects to do. The rotation direction N of the photosensitive drum 1 is the direction along the sub-scanning direction. The imaging lens 34 is a lens for adjusting the laser light reflected by the polygon mirror 33 so that the scanning speed in the main scanning direction on the photoconductor is constant and forming an image on the photoconductor. The mirror 35 is a mirror that reflects the laser light emitted from the imaging lens 34 so as to guide it onto the photoconductor. The light detection mirror 36 is a mirror that is provided close to the surface of the photoconductor and that reflects the laser light reflected by the mirror 35 so as to guide it to the light detection sensor 37. Light detection sensor 37
Detects the laser light reflected by the light detection mirror 36 and outputs a detection signal. The delay circuit 38 receives the detection signal output from the light detection sensor 37 and controls the optical modulator 32 after a predetermined time has elapsed.

The laser light emitted from the semiconductor laser 31 is modulated by the optical modulator 32 in accordance with the image information signal E such as a character string and a line drawing, reflected by the polygon mirror 33, and then the imaging lens 34. The reflected light is reflected by the mirror 35 and is focused on the image scanning line F along the main scanning direction on the photoconductor. In this way, the exposure unit 3 scans the photoconductor in the main scanning direction to form an electrostatic latent image.

When writing an image on the image scanning line F during image formation, the light detection sensor 37 is used by the light detection mirror 36.
The reflected light from the light is received and the detection signal is supplied to the delay circuit 38. After a predetermined delay time from the time when the detection signal is formed, the optical modulator 32 outputs the delay circuit 38 after a predetermined delay time. It is started by controlling. The image writing start position, that is, the exposure scanning start position in the main scanning direction with respect to the print data of the original image for which the presence or absence of exposure has been determined as the exposure target candidate is determined from the predetermined one end 1a in the rotation axis direction on the photoconductor. It is represented by the distance along the scanning direction. It may be different in the sub-scanning direction. The scan start position is changed by changing the image information signal E based on a signal indicating switching of the transfer paper P or the printing surface, for example, a signal corresponding to the number of rotations of one surface of the photosensitive drum 1 during printing. To do. That is, the scanning start position is the position A shown in the figure.
From the position B to the position B, the photosensitive member moves along the main scanning direction.

Next, FIG. 5 shows a control block diagram of a main part of the image forming apparatus according to the present embodiment. The image forming apparatus includes a CPU (Central Processing Unit) as a control unit main body.
nit) 51 is installed. In addition, an image processing unit 52 that performs image processing on print data, a ROM that stores fixed data such as program data executed by the CPU 51 and dot pattern data corresponding to various character codes.
A RAM (Random Acces) in which a (Read Only Memoly) 53, a data storage area such as a drawing memory 54a, a line counter memory 54b, and a shift counter memory 54c are formed.
s Memoly) 54, and a communication interface 55 that receives print data from the external connection terminal device 101 and the like. Further, the line buffer 56 capable of storing dot line data for one line, the semiconductor laser 31
Controller 57 for controlling the irradiation of the laser light generated on the photosensitive member, the I / O port 58 for outputting the image information signal E serving as a drive signal to the controller 57, the user setting for image formation, etc. An operation panel 59, an original reading device 60 for reading image data of an original image from an original D (hereinafter, D is omitted), and the like are mounted. The controller 57 corresponds to the one shown as the optical modulator 32 of the exposure unit 3 in FIG. The CPU 51, the image processing unit 52, the ROM 53, the RAM 54, the communication interface 55, the line buffer 56, the I / O port 58,
Operation panel 59, document reading device 60, and other I
The / O ports are connected by bus lines such as an address bus and a data bus.

Further, the image processing section 52 detects that the image data of the vertical ruled line is included in the print data at the time of double-sided printing, and is used for the control of the scanning start position described later. Further, the user can specify from the operation panel 59 whether or not the image data of the vertical ruled line is included.

FIG. 6 shows a storage state of print data. As shown in FIG. 6A, the drawing memory 54a of the RAM 54 is composed of dot line data represented by x + 1 bits "1" or "0" of 0 to x per line, and a line counter memory 54b. It is assumed that an area in which the print data (data of the exposure target candidate) of the original image from the line L = 1 having the count value L of 1 to the maximum N can be drawn is formed. The line buffer 56 is shown in FIG.
As shown in FIG. 5, it is assumed that an area capable of storing dot line data, which is more than the number of dots (= x + 1) of one line of the drawing memory 54a, is stored. In the same figure, an example is shown in which dot line data with three dots more can be stored. It is the count value S of the shift counter memory 54c that corresponds to which bit each of the above bits corresponds to x = 0 as 0th bit. The number of dots to be added to x + 1 is at least the number of dots corresponding to the vertical ruled line width for one scan start position change, and a wide area is secured to accommodate a plurality of print data scan start position changes. Has been done.

Next, by the image forming apparatus having the above-described configuration, print data including vertical ruled line image data is printed on the front surface and the back surface of a plurality of continuously supplied transfer papers P such as a form sheet. The case of performing double-sided printing will be described. The position of the vertical ruled line on the original image is the front side and the back side of the original (generally, the front side original image and the back side original image of the same size)
These are the same ruled lines on which an electrostatic latent image is formed along the sub-scanning direction of the photoconductor. Therefore, the image data of the vertical ruled lines is transferred for each transfer sheet P for one original document (generally, a set of the same size front surface image and back surface original image), and through the front surface printing and the back surface printing of each transfer paper P. Even if the scanning start position is different, the relative position of the electrostatic latent image in the scanning exposure range with respect to the data of the exposure target candidate (print data of the original image) on the photoconductor is the same.

As a first double-sided printing method, the flowchart of FIG. 7 shows the main part of a print control processing routine in which the CPU 51 executes the double-sided printing based on the program data stored in the ROM 53. When performing double-sided printing of a plurality of print data including image data of vertical ruled lines in succession, the control in the case of moving while changing the print position on the photoconductor along the main scanning direction is shown.

That is, when the CPU 51 starts this print control processing routine after the initialization processing (initialization) after the power supply of the image forming apparatus is turned on, for example, the CPU 51 first
Shift counter memory 54c as ST (step) 1
If the count value S (see FIG. 6 (b)) is reset to "0", then at ST2, the document is directly read from the document reading device 60 of the image forming apparatus main body, or an external connection terminal such as a personal computer is used. It waits to receive print data according to the print command via the device 101. When print data such as characters and ruled lines is received in this state, the print data is developed into a dot pattern based on the dot pattern data in the ROM 53 and drawn in the drawing memory 54a in ST3.

Next, at ST4, if the count value L (see FIG. 6A) of the line counter memory 54b is once reset to "0", this count value L is set at ST5.
Is incremented by "1". Thereafter, in ST6, the dot line data consisting of (x + 1) bits of the line address corresponding to the count value L is read from the drawing memory 54a. If the corresponding dot line data can be read out in ST7, the dot line data is transferred to the line buffer 56 via the bus line in ST8. At this time, the dot line data is stored with a shift from the head area of the line buffer 56 by the number of dots matching the count value S of the shift counter memory 54c. That is, if the count value S is “0”, the dot line data is stored in the area of S = 0 to x,
If the count value S is "1", S = 1 to (x + 1)
If the count value S is “2”, the dot line data is stored in the area S = 2 to (x + 2), and if the count value S is “3”, the dot line data is stored in the area = 3 to (x + 3) stores the dot line data.

If the dot line data for one line is transferred (set) to the line buffer 56 in ST8, the CPU 51 sends a drive signal from the I / O port 58 to the controller 57 (optical modulator 32) in ST9. The image information signal E (see FIG. 4) is transmitted to scan the scanning line F of the photoconductor.
The dot line data in the line buffer 56 is written above. Then, while synchronizing with the rotation of the photosensitive drum 1, the dot line data for the next and subsequent lines are sequentially written by laser light scanning. Then, each time one line of dot line data in the line buffer 56 is written by laser light scanning, the process returns to ST5, and if the counter value L of the line counter memory 54b is further incremented by "1", the processes of ST6 to ST9 are performed. repeat. Accordingly, the dot line data is sequentially read from the leading line of the dot pattern drawn in the drawing memory 54a and transferred to the line buffer 56, and the laser beam on the photoconductor is transferred according to the dot line data transferred to the line buffer 56. Scan.

On the other hand, in ST7, the line counter memory 5
When it is confirmed that there is no dot line data at the line address that matches the count value L of 4b, the drawing memory 54
It is considered that the printing of the dot pattern drawn on a is completed. After that, the process proceeds to ST10 and the shift counter memory 54c
The count value S of is incremented by "1". In addition, here, in order to make the description easy to understand, the vertical ruled line width is set to one dot, and the count value S is incremented by "1". Next, in ST11, it is determined whether or not the shift amount of the count value S exceeds the shift upper limit value, and if it exceeds, the count value S is reset to "0" in ST12. Note that the shift upper limit value is the maximum number that can be shifted when the dot line data for (x + 1) dots drawn in the drawing memory 54a is transferred to the line buffer 56, and in this embodiment, the line buffer 56 The upper limit shift value is "3" because the area for storing dot line data that is, for example, 3 dots more than the number of dots (= x + 1) for one line in the drawing memory 54a is stored. After updating the count value S in ST10 or ST12, the CPU 51 returns to ST2 and waits for reception of the next print data. When print data is received, the processes of ST3 to ST12 are repeated.

In the image forming apparatus of this embodiment having the above-described structure, when print data is received, the print data is expanded into a dot pattern and the drawing memory 54a.
Is drawn to. Then, from the top line of the dot patterns drawn in the drawing memory 54a, (x +
1) The dot line data of dots is read and transferred to the line buffer 56. At this time, if the count value S of the shift counter memory 54c is "0", all the dot line data of (x + 1) dots are transferred to the area of S = 0 to x of the line buffer 56.
Then, every time the dot line data for one line is transferred, laser light scanning is performed on the photoconductor according to the dot line data for the one line. When the count value S is “0”, the data of S = 0 to x is the data of the exposure target candidate (print data of the original image) that is determined whether or not to be exposed as a part of the print image. . The other data is not a print image, and is data that is not an exposure target candidate that is determined not to be exposed.

Thus, if the dot patterns drawn in the drawing memory 54a are sequentially output line by line,
At this time, the count value S of the shift counter memory 54c
"1" is added to. Therefore, the print data received next is developed into a dot pattern and drawn in the drawing memory 54a, and then (x +
1) The dot line data of dots is read out and transferred to the line buffer 56. At this time, all the dot line data of (x + 1) dots are transferred to the area S = 1 to (x + 1) of the line buffer 56. It Then, every time one line of dot line data is transferred, the printing unit 2
1 scans the laser beam, and the dot line data of the one line is written. When the count value S is “1”, the data of S = 1 to (x + 1) is the exposure target candidate data, and the data other than the above, such as the data of S = 0, is the data other than the exposure target candidate. That is, the print data output this time is printed with its print position shifted to the right (main scanning direction) of the print position of the print data printed immediately before.

Similarly, the print data received next is
Since "2" is counted as the count value S of the shift counter memory 54c, it is further shifted to the right by one dot for printing, and the print data received next is "2" as the count value S of the shift counter memory 54c. Since "3" has been counted, it is shifted to the right by one dot and printed. The exposure candidate data is shifted to the right by one dot. After printing this print data, the count value S returns to "0", so the print data received next is shifted to the left by 3 dots,
It is printed in the same position area as the print data three times before.

Therefore, the transfer sheet P supplied as the first sheet
When the scanning start position at the time of front side printing is the position represented by the position R1 on the photoconductor as shown in FIG. 1A, the scanning start position at the time of back side printing of the transfer paper P is The position R2 is moved from R1 in the main scanning direction. 1 as above
In the example in which the scanning start position is moved bit by bit, the position R2 is located at a dot adjacent to the dot at the position R1. Generally, since the width of the vertical ruled line is larger than 1 bit, the movement amount of the scanning start position may be set to a multiple of 1 bit. In the front surface printing of the second transfer paper P, the position R3 further moved in the main scanning direction from the position R2 becomes the scanning start position, and thereafter, the position R4, the position R5, the position R6, ... In this way, the scan start position is sequentially moved in the main scanning direction. When the shift amount of the count value S exceeds the shift upper limit value,
The scanning start position returns to the position R1 and moves as before. When there are multiple vertical ruled lines, the interval between the vertical ruled lines is usually sufficiently larger than the width of the vertical ruled lines, so that the electrostatic latent image formed on a certain vertical ruled line due to the movement of the scanning start position is different. It is unlikely that the position of the electrostatic latent image already formed with respect to the vertical ruled line is immediately reached. Also,
When the width of the vertical ruled line is large or small, the amount of one movement of the scanning start position may be set to be equal to or larger than the maximum vertical ruled line width. When the printing on all the transfer papers P is completed, the next first scanning start position is the position R1.

Therefore, for example, even if there is vertical ruled line image data as print data and continuous printing on both sides is requested, the vertical lines are changed for each print data (every time the front side printing and the back side printing are switched). The printing position of the ruled line is shifted in the main scanning direction. Then, until the count value S exceeds the upper limit value, the electrostatic latent image of the vertical ruled line is not formed through double-sided printing at the same position in the main scanning direction of the photoconductor. As a result, the electrostatic latent image of the vertical ruled line is not concentrated on a specific portion of the photoconductor, unlike black dots in black-and-white printing.
Further, if the amount of movement of the scanning start position is constant, such as the above-mentioned bit by bit, control is easy. In addition,
For single-sided printing, the scanning start position may be fixed at position R1 or the like.

Thus, according to the first double-sided printing method,
The CPU 51, the line buffer 56, and the shift counter memory 54c, which shifts the entire dot pattern developed in the drawing memory 54a in the main scanning direction, include a scanning start position control unit (first scanning start position control) that performs the following control. And to make).

That is, the CPU 51 and the line buffer 5
6 and the shift counter memory 54c, when printing on the back surface of all the transfer sheets P, the vertical ruled lines are static when the electrostatic latent image of the vertical ruled line is formed on the front surface immediately before the formation position in the main scanning direction. The scanning start position of the exposure as viewed in the main scanning direction is controlled so as not to overlap the formation position of the latent image as viewed in the main scanning direction. Further, for the transfer paper P supplied as the second and subsequent sheets, the transfer paper supplied immediately before the formation position of the electrostatic latent image of the vertical ruled line in the main scanning direction when printing on the front surface and the back surface. The scanning start position is controlled so as not to overlap the formation position of the electrostatic latent image of the vertical ruled line when printing on the back surface of P viewed in the main scanning direction.

Therefore, at the time of printing on the back surface of all the transfer papers P, the electrostatic latent image of the vertical ruled line is formed on the circumference of the photosensitive member in the portion where the electrostatic latent image of the vertical ruled line is formed at the time of printing on the front surface immediately before. No image is formed. Furthermore, the transfer paper P supplied as the second and subsequent sheets
On the other hand, when printing on the front surface, the electrostatic latent image of vertical ruled lines is not formed on the circumference of the photoconductor at the portion where the electrostatic latent image of vertical ruled lines was formed immediately before printing on the back surface, Further, at the time of printing on the back surface, an electrostatic latent image of vertical ruled lines is formed on the circumference of the photoconductor at the portion where the electrostatic latent image of vertical ruled lines was formed at the time of printing on the back surface of the transfer paper P supplied immediately before. Not formed.

Therefore, the exposure for the electrostatic latent image of the vertical ruled line is not continuously performed on the same partial peripheral surface of the photoconductor by the printing on the front and back sides and the printing on the back side. There is no possibility that the electrostatic latent images of the vertical ruled lines will be continuously exposed on the same partial peripheral surface of the photoconductor by printing on the back surfaces of the two transfer papers P fed back and forth. As a result, the frequency of exposure performed through double-sided printing on the same peripheral surface of the photoconductor is reduced, and damage due to exposure is reduced. That is, the degree of deterioration of a specific photoconductor portion does not become extremely large as compared with other photoconductor portions, and the degree of deterioration of each photoconductor portion is averaged. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the back surface, the damage due to the exposure is not so much, so that the deterioration of the peripheral surface which causes the image defect is suppressed. Therefore, it is possible to favorably prevent the life of the photoconductor from becoming particularly short.

As described above, even when performing double-sided printing in which vertical ruled lines having the same position on the original image are printed on the front surface and the back surface of a plurality of transfer materials that are continuously supplied, It is possible to provide an electrophotographic image forming apparatus capable of properly suppressing deterioration and extending the life of the photoconductor as compared with the conventional case.

As a second double-sided printing method, the flowchart of FIG. 8 shows the main part of a print control processing routine in which the CPU 51 executes the double-sided printing based on the program data stored in the ROM 53. In this flowchart, when performing double-sided printing on the transfer paper P continuously supplied with a plurality of print data including vertical ruled line image data, the scanning start positions of the single-sided print data and the front-side print data are always fixed. , Showing the control in the case of moving while changing the scanning start position of the back surface print data along the main scanning direction of the photosensitive member.

In ST21, the process waits until the document is directly read from the document reading device 60 of the main body of the image forming apparatus or the print data is received according to the print command through the external connection terminal device 101 such as a personal computer. When print data such as characters and ruled lines is received in this state, the process proceeds to ST22, and it is determined whether the printing is double-sided printing or single-sided printing. If it is double-sided printing, the process proceeds to ST23, and it is determined whether it is front-side printing or back-side printing. If printing on the front side proceeds to ST24, and if printing on the back side proceeds to ST31. If the one-sided printing is performed in ST22, the process proceeds to ST24.

Steps ST24 to ST27 performed in the case of single-sided printing or front-sided printing of double-sided printing are, in order, ST3 to S in FIG.
Same as T6. In ST28 following ST27, if the corresponding dot line data can be read,
At ST29, the dot line data is transferred to the line buffer 56 via the bus line. If the corresponding dot line data cannot be read in ST28, the process returns to ST21. After ST29, proceed to ST30,
The print data for one line is written on the photoconductor by exposure, and the process returns to ST26.

In the case of double-sided printing and back-side printing, the scanning start position is moved in the main scanning direction from the front-side printing scanning start position in ST31. Next, in ST32, the count value S is set to "0", and in ST33, the print data is developed into a dot pattern in the drawing memory 54a. ST34 to S following ST33
T42 is, in order, the same as ST4 to ST12 in FIG. 7. However, in the case of NO in ST41 and after ST42, the process returns to ST21.

In the case of the above flow chart, the scanning start position for single-sided printing and the transfer sheet P supplied as the first sheet.
When the scanning start position at the time of front surface printing is the position represented by the position R1 on the photoconductor as shown in FIG. 1B, the scanning start position at the time of the back surface printing of the transfer paper P is The position R2 is moved from R1 in the main scanning direction. 1 as above
In the example in which the scanning start position is moved bit by bit, the position R2 is located at a dot adjacent to the dot at the position R1. Further, the scanning start position returns to the position R1 again for the front surface printing of the second transfer paper P, and the position R2 for the back surface printing.
The position R3 further moved in the main scanning direction becomes the scanning start position, and thereafter, the position R3 is set every time the back side printing is started.
4, the position R5, the position R6, and so on, the scanning start position sequentially moves in the main scanning direction. When the shift amount of the count value S exceeds the shift upper limit value, the scanning start position returns to the position R2 and moves in the same manner as before in the back side printing.
When the printing on all the transfer papers P is completed, the scanning start position at the next first back surface printing is the position R2.

Therefore, for example, even if there is vertical ruled line image data as print data and continuous printing on both sides is requested, the print position of the vertical ruled line is shifted in the main scanning direction for each back side print data. To be done. Then, until the count value S exceeds the upper limit value, the electrostatic latent image of the vertical ruled line is not formed at the same position in the main scanning direction of the photoconductor during back surface printing. As a result, the electrostatic latent image of the vertical ruled line is not concentrated on a specific portion of the photoconductor, unlike black dots in black-and-white printing.

Thus, according to the second double-sided printing method,
The CPU 51, the line buffer 56, and the shift counter memory 54c, which shifts the entire dot pattern developed in the drawing memory 54a in the main scanning direction, include a scanning start position control unit (second scanning start position control) that performs the following control. And to make).

That is, the CPU 51 and the line buffer 5
6 and the shift counter memory 54c, when printing on the surface of all the transfer papers P, the same scanning start position of the exposure as seen in the main scanning direction of the electrostatic latent image of the vertical ruled lines on each transfer paper P. Control to be. Further, when printing on the back surface of all the transfer papers P, the formation position of the electrostatic latent image of the vertical ruled lines viewed in the main scanning direction is seen in the main scanning direction of the electrostatic latent image of the vertical ruled lines during printing on the front surface. The scanning start position is controlled so as not to overlap the formation position. Further, when printing on the back surface of the transfer paper P supplied as the second and subsequent sheets, printing on the back surface of the transfer paper P supplied immediately before the formation position of the electrostatic latent image of the vertical ruled line seen in the main scanning direction. The scanning start position is controlled so that it does not overlap with the formation position of the electrostatic latent image of the vertical ruled line in the main scanning direction.

Therefore, at the time of printing on the surface of all the transfer papers P, the scanning start position is the same for each transfer paper P. In addition, when printing on the back surface of all the transfer papers P, the electrostatic latent image of vertical ruled lines is not formed on the circumference of the photoconductor at the portion where the electrostatic latent image of vertical ruled lines was formed during printing on the front surface. Further, at the time of printing on the back surface of the transfer paper P supplied as the second and subsequent sheets, at the time of printing on the back surface of the transfer paper P supplied immediately before, the portion of the photoreceptor on which the electrostatic latent image of the vertical ruled line is formed No electrostatic latent image of vertical ruled lines is formed on the circumference.

Therefore, there is no possibility that the electrostatic latent image of the vertical ruled line is exposed on the same partial peripheral surface of the photosensitive member continuously by the printing on the front side and the printing on the back side. The electrostatic latent image of the vertical ruled line is not continuously exposed on the same partial peripheral surface of the photoconductor by printing on the back surfaces of the two transfer papers P that are supplied. As a result, the frequency of exposure performed through double-sided printing on the same peripheral surface of the photoconductor is reduced, and damage due to exposure is reduced. That is, the degree of deterioration of a specific photoconductor portion does not become extremely large as compared with other photoconductor portions, and the degree of deterioration of each photoconductor portion is averaged. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the back surface, the damage caused by the exposure is small,
Deterioration of the peripheral surface leading to the occurrence of image defects is suppressed, and it is possible to favorably prevent the life of the photoconductor from becoming particularly short.

As described above, even when performing double-sided printing in which vertical ruled lines having the same position on the original image are printed on the front surface and the back surface of a plurality of transfer materials that are continuously supplied, It is possible to provide an electrophotographic image forming apparatus capable of properly suppressing deterioration and extending the life of the photoconductor as compared with the conventional case.

The second scanning start position control means also functions as one of the first scanning start position control means, as can be seen from the overlapping relationship of the electrostatic latent images.

Table 1 shows the scanning start position and the amount of movement of the scanning start position in the above first double-sided printing method.
Table 2 shows the scanning start position and the amount of movement of the scanning start position in the double-sided printing method. The scanning start position movement amount is the movement amount from the time of the immediately preceding printing in Table 1,
In Table 2, the movement amount from the immediately preceding back side printing at each back side printing is shown.

[0069]

[Table 1]

[0070]

[Table 2]

In the first double-sided printing method, the scanning start position is moved successively even during front-side printing, so that deterioration of the photosensitive member is prevented.
Even a slight amount can be suppressed including the amount of time of surface printing. In addition, in each of the first and second double-sided printing methods, the scanning start position can be automatically moved, and the movement timing of the scanning start position can be measured by a counter that measures the number of sheets of the transfer paper P supplied. The control mechanism is simple because it is not necessary to decide from the result.

Although not described above, in the first and second double-sided printing methods, the exposure intensity of the exposure unit 3 at the time of printing on the back side is used as the image data of the ruled lines only for the image data of the ruled lines other than the vertical ruled lines. It is set the same as when printing print data that includes. The exposure intensity is
When the ruled lines are printed, the emission light intensity of the semiconductor laser 31 is normally set to the maximum value, and the back surface printing has the same exposure intensity as the front surface printing.

On the other hand, as shown in the following Tables 3 and 4, the exposure intensity at the time of back side printing in the first double-sided printing method includes only image data of ruled lines other than the vertical ruled lines. The third double-sided printing method (Table 3), which lowers the print data compared to the case where the print data is printed, and the exposure intensity at the time of the back side printing in the second double-sided printing method are included only in the image data of ruled lines other than the vertical ruled lines. Fourth double-sided printing method (Table 4) that reduces the print data compared to the case of printing
Can also be executed.

[0074]

[Table 3]

[0075]

[Table 4]

In these methods, the exposure intensity at the time of printing on the back surface is reduced by about 10% as compared with the case of printing the print data including only the image data of the ruled lines other than the vertical ruled lines. When the back side printing has the same exposure intensity as that of the front side printing, the exposure intensity is about 10% lower than that of the front side printing. Control to reduce the exposure intensity is CP
U51 performs, and CPU51 functions as an exposure intensity control means. In order to perform the process of lowering the exposure intensity at the time of printing on the back side, after setting the print data for one line in the line buffer 56 in each of the flowcharts of FIGS. 7 and 8, before writing the print data for one line, the exposure intensity is set. You can add a step to reduce

FIG. 2B shows changes in exposure level (exposure intensity) when the third double-sided printing method is executed. The exposure level at the time of printing on the front side is shown as a high level, and the exposure level at the time of printing on the back side is shown as a low level. FIG. 2A is the same as FIG. 1A. In addition, FIG. 2 shows changes in the exposure level (exposure intensity) when the fourth double-sided printing method is executed.
Similar to FIG. 2B, it is shown in FIG. 2 (c) is shown in FIG.
Same as (b).

In the image forming apparatus that executes the third double-sided printing method or the fourth double-sided printing method, the image forming apparatus that executes the first double-sided printing method or the image that executes the second double-sided printing method, respectively. In the forming apparatus, since the exposure intensity at the time of printing on the back surface is low, damage due to exposure is particularly small. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the back surface, the damage applied by the exposure is very small, so that the deterioration of the peripheral surface leading to the occurrence of an image defect does not occur. Especially suppressed,
It is possible to very satisfactorily avoid shortening the life of the photoconductor.

The image forming apparatus for executing the first to fourth double-sided printing methods has been described above, but the scanning start position control means in each method moves the scanning start position in units of exposure dots of the exposure unit 3. Thus, the scanning start position can be moved by a minute amount such as the vertical ruled line width. Therefore, it is possible to avoid the size increase of the apparatus due to the photosensitive drum being considerably enlarged in the main scanning direction or the photosensitive drum being moved, and the photosensitive drum can be moved or the transfer material supply position can be changed. There is no need for difficult control such as moving.

The above-mentioned image forming apparatus has a computer inside, and the image forming methods including the first to fourth double-sided printing methods are performed by the CPU 51 executing the programs in the ROM 53. RO
Computer-readable recording can be performed on various recording media including M53.

[0081]

As described above, according to the image forming apparatus of the present invention, the original image is formed on the first surface and the second surface of the plurality of transfer materials continuously supplied by the double-sided printing. When printing the original image print data including the image data of the vertical ruled line that is the ruled line in which the electrostatic latent image is formed along the sub-scanning direction of the photoconductor at the same position,
The scanning start position of the exposure as viewed in the main scanning direction of the photoconductor with respect to the print data is viewed in the main scanning direction of the electrostatic latent image of the vertical ruled line during printing on the second surface of all the transfer materials. The formation position is controlled so that it does not overlap with the formation position of the electrostatic latent image of the vertical ruled line seen in the main scanning direction immediately before printing on the first surface, and the second and subsequent sheets are supplied. At the time of printing on the first surface and the second surface of the transfer material, the formation position of the electrostatic latent image of the vertical ruled line seen in the main scanning direction is supplied immediately before to the second surface of the transfer material. It is configured to include a scanning start position control unit that controls the electrostatic latent image of the vertical ruled line at the time of printing so as not to overlap with the formation position as viewed in the main scanning direction.

Therefore, the frequency of exposure performed through double-sided printing on the same partial peripheral surface of the photoreceptor is reduced, and damage due to exposure is reduced. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the second surface, the damage due to the exposure is not so much, so that the peripheral surface is deteriorated which causes an image defect. Is suppressed, and it is possible to favorably prevent the life of the photoconductor from becoming particularly short.

As described above, even when performing double-sided printing in which vertical ruled lines having the same position on the original image are printed on the front surface and the back surface of a plurality of transfer materials that are continuously supplied, An effect of being able to provide an electrophotographic image forming apparatus capable of effectively suppressing deterioration and extending the life of the photoconductor as compared with the conventional case is provided.

Further, as described above, the image forming apparatus of the present invention forms an original image on the first surface and the second surface of the plurality of transfer materials continuously supplied by the double-sided printing. When the print data of the original image including the image data of the vertical ruled line which is the ruled line in which the electrostatic latent image is formed along the sub-scanning direction of the photoconductor is printed, The scanning start position of the exposure as viewed in the main scanning direction of the photoconductor with respect to the print data is controlled so as to be the same for each of the transfer materials at the time of printing on the first surface of all of the transfer materials. Of the electrostatic latent image of the vertical ruled lines when the transfer material is printed on the second surface of the electrostatic latent image of the vertical ruled lines when printing on the first surface. It is controlled so that it does not overlap with the formation position seen in the main scanning direction, and The transfer position of the electrostatic latent image of the vertical ruled line seen in the main scanning direction at the time of printing on the second surface of the transfer material supplied to the second surface of the transfer material supplied immediately before. It is configured to include a scanning start position control unit that controls the electrostatic latent image of the vertical ruled line at the time of printing so as not to overlap with the formation position as viewed in the main scanning direction.

Therefore, the frequency of exposure performed through double-sided printing on the same partial peripheral surface of the photoreceptor is reduced, and damage due to exposure is reduced. Therefore, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the second surface, the damage applied by the exposure is small, so that the deterioration of the peripheral surface leading to the occurrence of an image defect does not occur. It is possible to favorably prevent the life of the photoconductor from being shortened.

As described above, even when performing double-sided printing in which vertical ruled lines having the same position on the original image are printed on the front surface and the back surface of a plurality of transfer materials that are continuously supplied, An effect of being able to provide an electrophotographic image forming apparatus capable of effectively suppressing deterioration and extending the life of the photoconductor as compared with the conventional case is provided.

Further, as described above, the image forming apparatus of the present invention, when printing the print data including the image data of the vertical ruled lines, sets the exposure intensity at the time of printing on the second surface. The exposure intensity control means is provided so as to control the image data of the ruled line to be lower than that in the case of printing the print data including only the image data of the ruled line other than the vertical ruled line.

Therefore, since the exposure intensity at the time of printing on the second surface is small, the damage due to the exposure is particularly small. As a result, even if the same partial peripheral surface of the photoconductor is damaged by the transfer at the time of printing on the second surface, the damage applied by the exposure is very small, so that the peripheral surface leading to the occurrence of an image defect is generated. Is particularly suppressed, and the life of the photoconductor can be prevented from being particularly shortened.

Further, in the image forming apparatus of the present invention, as described above, the scanning start position control means controls the scanning start position so as to move it in units of exposure dots.

Therefore, it is possible to avoid an increase in the size of the apparatus due to the size of the photosensitive drum being made large in the main scanning direction or the photosensitive drum being moved, and at the same time, moving the photosensitive drum or transferring the transfer material. This has the effect that it is not necessary to perform difficult control such as moving the supply position of.

[Brief description of drawings]

1A and 1B are exposure change step diagrams showing changes in an exposure state in two types of double-sided printing methods executed by an image forming apparatus according to an embodiment of the present invention.

FIG. 2A to FIG. 2D are exposure change step diagrams showing changes in the exposure state in two other double-sided printing methods executed by the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a main part of a print-related portion of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of an exposure unit in the configuration of FIG.

FIG. 5 is a block diagram showing a control relationship of main parts of the image forming apparatus according to the embodiment of the present invention.

6A and 6B are memory state diagrams showing a storage state of print data.

FIG. 7 is a flowchart showing a processing flow of a first double-sided printing method.

FIG. 8 is a flowchart showing a processing flow of a second double-sided printing method.

[Explanation of symbols]

1 photoconductor drum 1a One end 2 charger 3 exposure section 4 developing device 6 transfer device 9 Fixing device 51 CPU (exposure intensity control means) M main scanning direction R1 to R6 positions (scan start position)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/29 H04N 1/04 104A 5C074 (72) Inventor Yoshitaka Matsumoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (No.) within SHARP Co., Ltd. HA13 HB08 HB11 XA05 5C074 AA20 BB02 BB17 CC22 CC26 DD15 EE02 EE04 EE08

Claims (4)

[Claims] 1. For each transfer material supplied so that a developed image on an image carrier is transferred, after the printing on the first surface, which is one surface of the transfer material, the next transfer material is transferred. In an electrophotographic image forming apparatus capable of double-sided printing, in which printing is performed on the second side, which is the other side, before being supplied, the above-mentioned transfer materials of a plurality of the transfer materials continuously supplied by the double-sided printing. The first surface and the second surface include image data of vertical ruled lines, which are ruled lines having the same position on the original image and on which an electrostatic latent image is formed along the sub-scanning direction of the photoconductor. When printing the print data of the original image, the scanning start position of the exposure in the main scanning direction of the photoconductor with respect to the print data is set to the vertical direction when printing on the second surface of all the transfer materials. The formation position of the electrostatic latent image of the ruled line when viewed in the main scanning direction is immediately before the first position. The electrostatic latent image of the vertical ruled lines is controlled so as not to overlap with the formation position as viewed in the main scanning direction at the time of printing on the surface, and the first surface of the transfer material supplied as the second and subsequent sheets and the above-mentioned first surface. At the time of printing on the second surface, the electrostatic latent image of the vertical ruled lines on the second surface of the transfer material supplied immediately before the formation position as seen in the main scanning direction of the electrostatic latent image of the vertical ruled lines at the time of printing on the second surface. An image forming apparatus comprising: a scanning start position control means for controlling a latent image so as not to overlap with a formation position of the latent image viewed in the main scanning direction. 2. For each transfer material supplied so that a developed image on the image carrier is transferred, after the printing on the first surface, which is one surface of the transfer material, the next transfer material is transferred. In an electrophotographic image forming apparatus capable of double-sided printing, in which printing is performed on the second side, which is the other side, before being supplied, the above-mentioned transfer materials of a plurality of the transfer materials continuously supplied by the double-sided printing. The first surface and the second surface include image data of vertical ruled lines, which are ruled lines having the same position on the original image and on which an electrostatic latent image is formed along the sub-scanning direction of the photoconductor. When the print data of the original image is printed, the scanning start position of the exposure as seen in the main scanning direction of the photoconductor with respect to the print data is set to the above-mentioned values when printing on the first surface of all the transfer materials. The transfer material is controlled to be the same, and the above The formation position of the electrostatic latent image of the vertical ruled lines seen in the main scanning direction at the time of printing on the second surface is seen in the main scanning direction of the electrostatic latent image of the vertical ruled lines at the time of printing on the first side. Control so that it does not overlap with the
At the time of printing on the second surface of the transfer material supplied as the second and subsequent sheets, the formation position of the electrostatic latent image of the vertical ruled line seen in the main scanning direction is immediately before the transfer material supplied to the second surface. An image forming apparatus, comprising: a scanning start position control means for controlling the electrostatic latent image of the vertical ruled line so as not to overlap with the formation position as viewed in the main scanning direction during printing on two surfaces. 3. When printing the print data including the image data of the vertical ruled lines, the exposure intensity at the time of printing on the second surface is used as the image data of the ruled lines of the ruled lines other than the vertical ruled lines. The image forming apparatus according to claim 1 or 2, further comprising an exposure intensity control unit that controls the print data including only the image data to be lower than when the print data is printed. 4. The image forming apparatus according to claim 1, wherein the scanning start position control means controls the scanning start position so that the scanning start position is moved in units of exposure dots.