JPH11218979A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always form an excellent image by controlling an image forming position decided according to synchronizing timing between a toner image formed on an image carrier in accordance with the thickness of transfer material and the transfer material carrier to the surface of the image carrier. SOLUTION: When a copying job is started, a system control part 41 discriminates whether paper is fed from a manual feeding tray or a paper feeding tray. When judged that the paper has been fed from the manual feeding tray, the control part 41 discriminates, based on the detected result by a thickness detection sensor 36 whether or not transfer paper fed from the manual feeding tray is cardboard. In the case of judging that the transfer paper is not the cardboard, the write starting position of an ROS(raster output scanner) is adjusted by a normal shift amount and the image is adjusted so as to output the image written by the ROS. In the case of judging that the transfer paper is the cardboard, the write starting position of the ROS is adjusted by a value obtained by adding the adjusting amount at the time when the transfer paper is the cardboard to the normal shift amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus which always forms an image at an appropriate position not only on plain paper but also on thick paper. The present invention relates to an image forming apparatus capable of performing the following.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus such as the above-mentioned electrophotographic copying machine, printer or facsimile,
For example, there is the following. This image forming apparatus forms a toner image on a photosensitive drum in accordance with an image of a document, and transfers a transfer sheet fed from a paper feed cassette in a horizontal direction with respect to the photosensitive drum, while Instead of transferring the toner image formed on the drum onto the transfer paper, the transfer paper fed from the paper feed cassette is transported vertically downward from the upper side of the photosensitive drum while being transported upward. The toner image formed on the photoconductor drum is transferred onto a transfer sheet by a transfer roll, and the transfer sheet on which the toner image has been transferred is directly conveyed vertically upward and is positioned above the transfer position of the photoconductor drum. The fixing device performs a fixing process, and discharges the transfer sheet subjected to the fixing process onto a sheet discharge tray provided in an upper portion of the image forming apparatus main body. This image forming apparatus does not need to provide a paper discharge tray on the side of the main body, so that the installation space of the image forming apparatus can be reduced, the space can be saved, and the image forming apparatus is fixed vertically above the photosensitive drum. Since it is sufficient to dispose the apparatus and the like, the width of the image forming apparatus main body itself can be reduced correspondingly, and the apparatus can be downsized.

By the way, in the image forming apparatus configured as described above, similarly to the conventional image forming apparatus, the transfer sheet is prevented from being wound around the fixing roll and the binding margin is formed. In some cases, a predetermined margin may be formed at the tip of the.

In the above-described image forming apparatus, as a technique for adjusting the margin in order to form an appropriate margin at the leading end of a transfer sheet, for example, Japanese Patent Laid-Open No. 59-147 discloses a technique.
The one disclosed in Japanese Patent Publication No. 364 has already been proposed. The image shift device of a copying machine according to Japanese Patent Application Laid-Open No. 59-147364 discloses an image shifter for an original by operating a consensus or a predetermined order by combining +-or switches used in a normal copying operation. Shift mode setting means for setting a state in which the image is shifted with respect to the paper on which the image is to be copied, a +-or switch for inputting setting data relating to the image shift amount in the state in which the mode is set, and storing the setting data. And a transfer position adjusting means for adjusting the copy position of the sheet with respect to the area where the image is formed on the photoconductor in accordance with the image shift amount.

In the case of the image forming apparatus constructed as described above, while the transfer sheet is conveyed from below to above in the vertical direction with respect to the transfer position of the photosensitive drum, the transfer paper is placed on the photosensitive drum. Is configured to transfer the toner image formed on the photoconductor drum to a transfer sheet, so that a part of the toner image formed on the photoconductor drum is moved downward from the photoconductor drum before moving to the transfer position. There is a problem in that the transfer sheet may fall and adhere to the transfer sheet positioned below the transfer sheet, thereby contaminating the transfer sheet.

In order to solve the above-mentioned problem of stain on transfer paper, the present applicant has disclosed Japanese Patent Application Laid-Open No. Hei 8-21.
Japanese Patent Application No. 1753 and Japanese Patent Application No. 8-275898 have already been proposed.

The image forming apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 8-211753 is intended to reduce the stain on the paper surface before transfer in vertical transfer. A transfer device disposed on the side of the image carrier for transferring the transfer material conveyed from below to above, and a transfer area where the developed image is transferred to the transfer member. In the image forming apparatus, which is provided below and has a guide unit for guiding the transfer material to the transfer area, the guide unit may be configured such that an upper portion to which the transfer material is fed comes into contact with each other and the transfer material passes. Thus, the upper portion is provided with two contact members that can be spread out by an amount by which the transfer material can pass.

The transfer device of the image forming apparatus according to Japanese Patent Application No. 8-275898 is a transfer device provided with a shield plate for preventing toner from entering a paper guide. The purpose is to prevent paper stains and bleeding of the transferred image due to the plate,
An image carrier on which a toner image is formed, a transfer device arranged on the side of the image carrier, the transfer device forming a transfer area between the image carrier, and a transfer device below the transfer region. Guide means having a pair of opposed guide members arranged to guide the sheet upward from the bottom toward the transfer area, wherein the image forming apparatus transfers the toner image of the image carrier to the sheet in the transfer area. In the transfer device, the guide unit is configured such that an upper end of one of the guide members of the guide unit is elastically pressed against the sheet when the sheet passes, and an upper end of the one guide member of the guide unit when the sheet passes. It is provided with a flexible shielding plate that comes into contact with the flexible shielding plate, and the distal end of the flexible shielding plate is bent in the direction of the upper end of one of the guide members of the guide means. It is.

[0009]

However, the prior art described above has the following problems. That is, in an image forming apparatus configured to transport a transfer sheet vertically from below and form an image on the transfer sheet as in the image forming apparatus, a conventional image forming apparatus is used. Similar to the forming apparatus, it is necessary to form a predetermined margin at the leading end of the transfer sheet. As a technique for this, for example, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. H8-211753, an image shift Technology has already been proposed. However, as described above, in an image forming apparatus that forms an image by transferring a transfer sheet from below to above along a vertical direction, Japanese Patent Application Laid-Open No. H08-211
As disclosed in Japanese Unexamined Patent Application Publication No. 753/75 and already proposed in Japanese Patent Application No. 8-2785898, a transfer material such as a transfer sheet is guided to the transfer area in order to prevent the transfer sheet from being stained before the transfer. The guide means is configured such that the upper portion from which the material to be transferred is brought into contact with each other, and the upper portion is provided with two contact members which are pushed apart by an amount by which the material to be transferred can pass when the material to be transferred passes. Or a pair of opposing guide members arranged below the transfer area and guiding the sheet upward from the bottom toward the transfer area, the upper end of one of the guide members of the guide means is elastically attached to the sheet when the sheet passes. And a flexible shielding plate that contacts the upper end of one of the guiding members of the guiding means when the paper is passed through, and the tip of the flexible shielding plate is One way of means Need for or configuration occurs as the bending in the direction of the upper end portion of the member.

However, as described above, the guide means pushes and spreads the upper portion to which the material to be transferred is brought into contact with each other and the upper portion of the upper portion through which the material to be transferred passes allows the upper portion to pass. The guide member may be configured such that the upper end of one of the guide members of the guide means is elastically pressed against the sheet when the sheet passes, and the guide means is pressed when the sheet is passed. When a flexible shielding plate is provided so as to be in contact with the upper end of one of the guide members, the rigidity of the transfer sheet when passing through the guide means or the guide member varies depending on the thickness and type of the sheet. The elasticity of the contact member of the guide means and the flexibility of the guide member are set according to the rigidity of the plain paper. Therefore, when the transfer paper is plain paper, the leading edge of the transfer paper pushes up the contact member and the shield plate in an appropriate state, passes through the contact member and the shield plate, and the photosensitive drum at a predetermined timing. It is transported to the transfer position on the front surface. Therefore, the toner image formed on the photosensitive drum is transferred in a state in which a predetermined blank portion is formed at the leading end of the transfer sheet.

On the other hand, when the transfer paper is thick paper such as a postcard, the rigidity of the transfer paper is greater than that of plain paper. Then, the paper passes through the contact member, the shielding plate, or the like, and is conveyed to the transfer position on the surface of the photoconductor drum earlier than a predetermined timing, and the leading end of the cardboard is narrower than a predetermined margin. There is a problem that only a blank portion is formed, and in some cases, an image may be chipped at the leading end of the cardboard.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to solve the problem even when the transfer material is thick paper other than plain paper. It is possible to adjust the image forming position,
An image can always be formed at the appropriate position on the transfer material,
An object of the present invention is to provide an image forming apparatus capable of always forming a good image on a transfer material.

[0013]

That is, according to the first aspect of the present invention, a transfer material is transferred from a lower portion of a toner image formed on an image carrier to an upper portion of the image carrier in a direction perpendicular to the image carrier. An image forming apparatus having a movable member that guides a transfer material to a transfer position in front of a transfer position of the image carrier while transferring the image to the image carrier according to a thickness of the transfer material. And an image forming position control means for controlling an image forming position determined by a synchronization timing between the toner image formed on the image carrier and the transfer material conveyed to the surface of the image carrier. As described above, the present invention is characterized in that the image forming position can be controlled according to the thickness of the transfer material, and it is only necessary to form a predetermined margin at the leading end of the transfer material. Instead, by controlling the image formation position on the transfer material, it is possible to always form an image at a favorable position regardless of the thickness of the transfer material. The thickness of the transfer material is, for example, a thickness detection unit that automatically detects the thickness of the transfer material is used. However, the thickness is not limited thereto. It is also possible to use one that is recognized by manually setting from.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIGS. 2 and 3 are block diagrams showing a digital copying machine having the functions of a copying machine / facsimile / printer as an embodiment of the image forming apparatus according to the present invention.

In FIGS. 2 and 3, reference numeral 1 denotes a main body of the digital copying machine.
In the upper part of the digital copying machine, an image reading device for automatically reading an image of a document is provided, and inside the digital copying machine main body 1, an image output unit 2 for outputting an image is provided. . The image output unit 2 in the digital copier main body 1 performs predetermined image processing on image information of a document read by an image reading device or image information sent from a communication line or a personal computer as necessary. And an ROS 4 (Raster Output Scanner) that performs image exposure based on image information on which predetermined image processing has been performed by the image processing device 3. Depending on the laser light L
Image exposure by B is performed.

As shown in FIG. 2, the ROS 4 emits a laser beam LB from a semiconductor laser (not shown) according to gradation data of image information. The laser beam LB emitted from the semiconductor laser is deflected and scanned by the rotating polygon mirror 5 and is scanned and exposed on the photosensitive drum 7 via the reflection mirror 6.

As the photosensitive drum 7 on which the laser beam LB is scanned and exposed by the ROS 4, for example, a photosensitive body using an organic photoconductive material is used. Is driven to rotate at a predetermined speed in the direction of the arrow. As shown in FIG. 2, the surface of the photosensitive drum 7 is previously charged to a predetermined potential by a charging roll 8 and then scanned and exposed to laser light LB in accordance with image information to form an electrostatic latent image. It is formed. The electrostatic latent image formed on the photosensitive drum 7 is developed by the developing roll 10 of the developing device 9 to become a toner image.

The toner image formed on the photosensitive drum 7 is transferred onto a transfer sheet 12 as a transfer material by a transfer roll 11 arranged so as to come into contact with the photosensitive drum 7, and the toner The recording sheet 12 to which the image has been transferred is neutralized by a separation charger 13 formed of a needle-shaped electrode and separated from the photosensitive drum 7. An AC voltage obtained by superimposing an AC voltage or a DC voltage is applied to the separation charger 13 including the needle-shaped electrodes.
As shown in FIG. 2, the transfer paper 12 includes a plurality of paper cassettes 1 arranged at a lower portion in the digital copier main body 1.
Paper is fed from 4, 15 and 16 by a paper feed roll 17. The fed transfer paper 12 is transported to the surface of the photosensitive drum 7 by the transport roll 18 and the registration roll 19.

The transfer paper 12 onto which the toner image has been transferred from the photosensitive drum 7 is discharged from the surface of the photosensitive drum 7 by the charge removal unit 13 composed of needle-shaped electrodes, as described above. After the toner image is conveyed to the fixing device 20, the toner image is fixed on the transfer paper 12 by heat and pressure by the fixing device 20,
As a result, the image is discharged onto the paper discharge tray 22 and the image forming process is completed.

After the toner image transfer step is completed, the surface of the photosensitive drum 7 is cleaned of residual toner, paper dust, and the like by a cleaning device 23 having a cleaner blade, a brush, and the like. Is prepared for.

In the digital copying machine constructed as described above, the photosensitive drum 7 and the developing device 9 and the cleaning device 23 around the photosensitive drum 7 are improved in order to improve the maintenance.
And the like are integrally formed as a unit as a process cartridge 24. The process cartridge 24 is integrally detachable from the digital copying machine body 1. Further, the process cartridge 24 is set so that the timing of deterioration of the photosensitive drum 7 and the timing of consumption of the developer in the developing device 9 are substantially the same. When the developer in the developing device 9 is consumed, the photosensitive drum 7 and the developing device 9 are not replaced with a new one individually. 9 can be removed from the digital copier body 1 and replaced with a new one, thereby improving maintainability.

Further, in the case of the digital copying machine constructed as described above, the transfer paper 12 is conveyed vertically downward from the transfer position of the photosensitive drum 7 while the transfer paper 12 is conveyed upward. The toner image formed on the drum 7 is configured to be transferred to the transfer paper 12. Therefore, a part of the toner image formed on the photosensitive drum 7 falls down from the photosensitive drum 7 before moving to the transfer position, adheres to the transfer paper 12 located thereunder, and is transferred. There is a possibility that the paper 12 is soiled.

Therefore, in the digital copying machine according to the present embodiment, as shown in FIG. 4, a transfer roll 11 arranged on the side of the photosensitive drum 7 and a transfer paper 12 arranged below the transfer area are formed. And a guide unit 33 having a pair of opposed guide members 31 and 32 for guiding the transfer region from below to above, and transferring the toner image of the photosensitive drum 7 to the transfer paper 12 in the transfer region. In the apparatus, the upper end of one of the guide members 31 of the guide means 33 is elastically pressed against the transfer paper 12 when the transfer paper 12 passes, and the guide means 33 when the transfer paper 12 is passed. A flexible shielding plate 34 that comes into contact with the upper end of one of the guiding members 32, and the distal end of the flexible shielding plate 34 is
The third guide member 32 is configured to be bent in the direction of the upper end. Further, the digital copying machine is provided with a manual feed tray 35 for manually feeding the transfer paper 12 made of thick paper such as a postcard.

The image forming apparatus according to this embodiment has a thickness detecting means for detecting the thickness of the transfer material, and is formed on the image carrier in accordance with the detection result of the thickness detecting means. And a timing control unit for controlling the synchronization timing between the toner image and the transfer material conveyed to the surface of the image carrier.

That is, in the digital copying machine according to this embodiment, as shown in the figure, a thickness detecting sensor 36 for detecting the thickness of the transfer paper 12 as a transfer material is provided at the base end of the manual feed tray 35. Is provided. The thickness detection sensor 36 is provided on the downstream side of the paper feed roller 37 of the manual feed tray 35 with the ultrasonic oscillator 3 provided between the paper conveyance path.
6a and an ultrasonic receiver 36b, and the timing at which the ultrasonic wave output from the ultrasonic oscillator 36a is received by the ultrasonic receiver 36b differs due to a change in the thickness of the transfer sheet 12. Utilizing this, a device that detects the thickness of the transfer paper 12 is used. However, the present invention is not limited to this, and the thickness detection sensor 36 is disposed downstream of the paper feed roller 37 and sandwiches the transfer paper 12 conveyed by the paper feed roller 37. It is equipped with two sensor levers that are in contact with both sides of the transfer paper, and the gap between the two sensor levers is changed by taking advantage of the fact that the distance between the two sensor levers changes due to the difference in the thickness of the transfer paper. Alternatively, a device that detects the thickness of the transfer sheet by optically detecting the thickness of the transfer sheet may be used. Also, as the thickness detection sensor,
It is not limited to the one that directly detects the thickness of the transfer paper.When the user makes a copy on the thick paper on the control panel of the digital copying machine, the thick paper key on the control panel indicates that the paper is thick. A configuration may be adopted in which the input by the user detects that the transfer paper is thick paper.

FIG. 1 is a block diagram showing a control circuit of a digital copying machine according to the present invention.

In FIG. 1, reference numeral 40 denotes an operator unit comprising a control panel or the like for operating a copy operation of the digital copying machine constructed as described above, and 41 denotes a copy operation or the like based on an instruction output from the operator unit 40. A system control unit including a CPU, a ROM, and the like for controlling
2 is a management data unit including a RAM or the like for managing data necessary for control in the system control unit 41, 43 is an image reading unit including an image reading device that reads an image of a document,
An image output unit 44 performs an image output operation under the control of the system control unit.
Is an image storage unit 45 composed of a RAM or the like, a thickness detection unit 36 composed of the thickness detection sensor for detecting the thickness of a transfer sheet as a transfer material, and a print controlling an image forming operation of the image output unit 44. And a control unit 46.

FIG. 5 is a block diagram showing an image forming operation control circuit for controlling the image forming operation of the digital copying machine according to the present invention.

In FIG. 5, reference numeral 51 denotes a CPU for controlling an image forming operation; 52, an ASIC for processing an image signal under the control of the CPU 51; 53, an FROM for storing a predetermined program and the like connected to the ASIC 52; 5
Reference numeral 4 denotes an SRAM connected to the ASIC 52 for storing a part of a program necessary for an image forming operation, 55 denotes an SRAM connected to the ASIC 52 for storing a part of a program necessary for an image forming operation, and 56 denotes a SRAM. The above ASIC
EEPR for storing predetermined parameters connected to 52
OM, 57 is a ROS control block for controlling the ROS, 58 is a timing generator for taking the timing of the image forming operation, 59 is a video interface for outputting image data to the ROS 3 via the ASG 60, 41 is an image output of the image output unit 44 3 shows a system control unit that controls operations.

The ASIC 52 is configured to control the timing at which the photosensitive drum 7 starts exposing an image based on the SOS signal output from the SOS terminal to the ROS control block 57. Further, a signal from the thickness detection sensor 36 is input to the CPU 51, and the ASIC 52 controls the timing at which the ASIC 52 starts exposing an image on the photosensitive drum 7 according to the detection result of the thickness detection sensor 36. Output a signal.

In the image forming apparatus according to this embodiment, even if the transfer material is thick paper other than plain paper, the image forming apparatus according to the present embodiment always fits the transfer material to the leading end of the transfer material. A good margin can be formed, and a good image can always be transferred to the transfer material.

That is, in the image forming apparatus according to this embodiment, as shown in FIG. 6, the shift amount (for example, 2 mm) of the transfer paper having a normal thickness and the adjustment value (for example, the shift amount for the thick paper) , ± 1.5 mm) is stored in the management data section 42 composed of the RAM in FIG. 1 (step 101). Next, the user sets the document on the image reading device 43,
When a copy job is started by pressing a copy button on the control panel 40 (step 102), the system control unit 41 determines whether paper is fed from the manual feed tray 35 or a paper cassette (step 103). If it is determined that the paper is fed from the paper feed cassette instead of from the manual feed tray 35, the writing start position of the ROS 3 is adjusted with the normal shift amount T1 as shown in FIG. (Step 104) Adjust the image and output the image written by ROS3 (Step 105). Thereafter, it is determined whether or not the job has been completed (step 106). If the job has been completed, the operation is terminated as it is. If the job has not been completed, the process returns to step 103 to continue the operation. .

On the other hand, if the system controller 41 determines that the paper is fed from the manual feed tray 35, the system controller 41 determines whether the transfer paper 12 fed from the manual feed tray 35 is thick paper.
The determination is made based on the detection result of the thickness detection sensor 36 (step 107). If it is determined that the transfer paper 12 is not thick paper, similar to the normal transfer paper described above,
The write start position of the ROS is adjusted with a normal shift amount (step 104), and the image is adjusted to
Output the image written in S3 (Step 1)
05). When it is determined that the transfer paper is thick paper, as shown in FIG. 8, the normal shift amount (for example, 2 m
The writing start position of the ROS 3 is adjusted by the value T2 obtained by adding the adjustment amount (for example, +1.5 mm) for thick paper to the m) (step 108). Then, similarly to the normal transfer paper 12, the image is adjusted and the image written by the ROS 3 is output (step 105). Further, it is determined whether or not the job has been completed (step 106). If the job has been completed, the operation is terminated as it is. If the job has not been completed, the process returns to step 103 to continue the operation. .

As described above, in the digital copying machine according to the above-described embodiment, the thickness detection sensor 36 detects whether or not the transfer paper 12 fed from the manual feed tray 35 is thick paper. If it is determined that the transfer paper is a normal transfer paper, a predetermined margin is formed at the leading end of the transfer paper 12 when an image is written on the photosensitive drum 7 by the ROS 3 as shown in FIG. Next, the image writing timing is controlled. The transfer paper 12
Is determined to be thick paper, as shown in FIG.
When writing an image on the photoconductor drum 7 by the ROS 3, an adjustment amount (for example, +1) for thick paper is set to a normal shift amount (for example, 2 mm) so that a predetermined margin is formed at the leading end of the transfer paper 12. .5 mm) and T2
By adjusting the write start position of the ROS 3, a predetermined margin can be formed at the leading end of the thick paper even when the transfer paper 12 is a thick paper other than the plain paper. An appropriate margin can be formed at the leading end of the transfer sheet 12, and a good image can always be transferred to the transfer sheet 12.

In the above-described embodiment, whether or not the transfer paper is thick paper is detected by the thickness detection sensor provided on the manual feed tray. However, whether or not the transfer paper stored in the paper cassette is thick paper is detected. Of course, it may be configured so as to perform the above.

Further, in the above-described embodiment, the image position of the paper is adjusted to adjust the ROS writing start timing. However, the present invention is not limited to this, and the image is adjusted to be transferred to the transfer position on the photosensitive drum. Needless to say, the configuration may be such that the transport start timing of the registration roll that transports the sheet is controlled.

[0038]

As described above, according to the present invention, even when the transfer material is thick paper other than plain paper, the image forming position can be adjusted, and the transfer material can always be properly adjusted. An image forming apparatus capable of forming an image at a position and always forming a good image on a transfer material can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control circuit of a digital copying machine according to an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a configuration diagram showing a digital copying machine according to an embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a configuration diagram showing a digital copying machine according to an embodiment of the image forming apparatus according to the present invention.

FIG. 4 is a main part configuration diagram showing a digital copying machine according to an embodiment of the image forming apparatus according to the present invention;

FIG. 5 is a block diagram showing a control circuit for an image forming operation.

FIG. 6 is a flowchart showing a control operation of the image forming operation.

FIG. 7 is a timing chart showing a control operation of the image forming operation.

FIG. 8 is a timing chart showing a control operation of the image forming operation.

[Explanation of symbols]

40: operator unit, 41: system control unit, 42: management data unit, 43: image reading unit, 44: image output unit, 4
5: image storage unit, 36: thickness detection unit, 46: print control unit.

Claims (1)

[Claims] 1. A method for transferring a toner image formed on an image carrier while transporting a transfer material from below to above the image carrier in a vertical direction and transferring the toner image to a position before the transfer position of the image carrier. An image forming apparatus having a movable member for guiding a transfer material to a transfer position on a side thereof, a toner image formed on the image carrier according to a thickness of the transfer material, and a toner image formed on a surface of the image carrier. An image forming apparatus comprising: an image forming position control unit that controls an image forming position determined by a synchronization timing with a conveyed transfer material.