JP2002258680A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where a user is not troubled by any manual procedure by not having the magnifying ratio of a toner image changed for a backside surface regardless of the type of recording material in a both sides mode and waste of recording material is prevented by inhibiting image formation of a both sides mode for the recording material where image formation is not intended for both sides. SOLUTION: In the image forming device provided with the both sides mode, an exclusive recording material for measuring the shrinkage rate after being passed through a fixing device and the recording material where image formation is carried out for the backside in the magnification corresponding to the shrinkage ratio are ejected to different paper ejecting trays. A judging means to judge whether the recording material is one where image formation is possible on both sides is included and when judgement is made that image formation cannot be carried out on both sides, the feeding of the recording paper is inhibited.

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 having a duplex mode for forming images on both sides of a recording material.

[0002]

2. Description of the Related Art 2. Description of the Related Art In an electrophotographic image forming apparatus, an image is obtained by transferring a toner image onto a recording sheet and then performing heat fixing. However, when the image is fixed by heating, the moisture contained in the recording paper evaporates due to the heat, so that after the fixing, the recording paper contracts and undergoes a dimensional change. This shrinkage ratio varies depending on the type and thickness of the recording paper, but is about 0.1 to 0.5% in length, but it takes 15 to 20 minutes to absorb water again to expand and return to the original size. It takes about. As the recording paper contracts / extends, the image carried on the recording paper also undergoes a dimensional change.

Therefore, in the duplex mode in which an image is formed on both sides of a recording sheet, an image is transferred and fixed on the front side (first side), and the image is formed on the back side (second side) in a state where the recording sheet is contracted. However, when the image returns to the original size, the image is enlarged, and the enlargement magnification changes on the front and back surfaces.

For example, in Japanese Patent Application Laid-Open No. Hei 6-332275, the contraction rate is stored in advance for each type of recording paper, and in the duplex mode, the image on the back side is automatically set by setting the type of recording paper. There is proposed an image forming apparatus that changes the enlargement magnification of an image. However, in this case, a type of recording paper in which the contraction rate is not stored in advance cannot be used.

Japanese Patent Application Laid-Open No. H10-149057 discloses an image forming apparatus which measures a shrinkage ratio on a first recording sheet and forms an image on the back surface of the second and subsequent sheets at a magnification corresponding to the shrinkage ratio. Is disclosed. However, the first recording paper dedicated to measurement and the second and subsequent recording papers on both sides of which images are formed are handled in a mixed manner, and the work of selecting only the recording material on which images are formed increases. The user had a problem. 2. From the viewpoint of resource saving, a recording sheet on which an image is already formed on one side (referred to as a backing sheet) may be reused and used for image formation. Further, there is a case where special paper which should form an image only on one side is used as a recording paper. When such backing paper or special paper is stored in the paper feed unit, if the paper feed unit is manually or automatically selected as the recording paper for image formation and the duplex mode is selected. However, image formation is performed on both sides of the recording paper on which images should not be formed on both sides. 2. Description of the Related Art Recent image forming apparatuses such as copiers have a type in which a paper supply unit has a large number of paper supply trays, accommodates various types of recording paper, and automatically selects a paper supply tray according to image forming settings. However, since such a selection of the paper feed tray is performed only by the size of the recording paper suitable for image formation, the above-mentioned problem often occurs. When images are formed on both sides of the recording paper that the user does not want,
Naturally, recording paper is wasted.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has the following objects. 1. Provided is an image forming apparatus in which a magnifying power of a toner image on a front surface and a back surface does not change regardless of a type of a recording material in a double-sided mode, and does not require a user to perform manual operations or the like. 2. Provided is an image forming apparatus in which image formation in a double-sided mode is prohibited for a recording material for which it is not desired to form an image on both sides, and the recording material is not wasted.

[0007]

The above object of the present invention has been attained by the following constitutions.

[0008] 1. A latent image is formed by imagewise exposing the photoconductor, and a toner image obtained by developing the latent image is
The recording material is transferred to the first surface of the recording material by the transfer unit, and is fixed by the fixing unit. Then, the recording material, which has been turned upside down by the reversing unit, is transported again to the transfer area, and a new toner image formed on the photoconductor is formed. Is transferred to the second surface of the recording material by the transfer means, is fixed by the fixing means, and is discharged to the outside of the image forming apparatus. Measuring means for measuring a longitudinal dimension and a lateral dimension of the recording material before and after fixing, and a longitudinal dimension before and after fixing of the recording material by the fixing means measured by the measuring means Control means for calculating a contraction rate of the recording material by the fixing means from the horizontal dimension and forming a toner image on the photoconductor at a magnification corresponding to the contraction rate. Eye recording material For the second and subsequent recording materials, a toner image to be transferred to the first surface is formed on the photoconductor by ordinary image formation, and the same recording material is used for the second and subsequent recording materials. The toner image transferred to the second surface is formed on the photoreceptor with a toner image having a magnification corresponding to the contraction rate calculated on the first sheet of recording material. An image forming apparatus having a measurement mode in which a second and subsequent recording materials are distinguished from each other and discharged to the outside of the apparatus.

[0009] 2. The apparatus according to the first aspect, further comprising a plurality of discharge trays, wherein the first recording material is discharged to a first discharge tray, and the second and subsequent recording materials are discharged to a second discharge tray. An image forming apparatus according to claim 1.

[0010] 3. 3. The printer according to 1 or 2, further comprising a total counter for counting and displaying the number of recording materials discharged to the outside of the apparatus, wherein the first recording material is not included in the count of the total counter. Image forming apparatus.

4. The image forming apparatus according to any one of claims 1 to 3, wherein the measuring unit that measures the lateral dimension of the recording material is a CCD or a CIS.

5. A measuring unit for measuring a lateral dimension of the recording material, a conveyance path from a paper feeding unit to the transfer area when transferring the toner image onto the first surface of the recording material, and a second surface of the recording material. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is arranged in a portion where a conveyance path from a re-sending section to a transfer area when a toner image is transferred to the transfer area overlaps.

6. The image forming apparatus according to any one of claims 1 to 5, wherein the measuring unit that measures a vertical dimension of the recording material measures the vertical dimension by measuring a passage time of the recording material. .

7. Exposure to form a latent image on the photoconductor is performed by scanning and exposing the photoconductor in the horizontal direction with a laser beam while moving the photoconductor in the vertical direction. The combined toner image is formed by changing the magnification of the vertical dimension by changing the moving speed of the photoconductor, and changing the magnification of the horizontal dimension by changing the speed of the scanning exposure. The image forming apparatus according to any one of claims 1 to 6, wherein

[8] Any one of the above items 1 to 7, wherein the measuring unit also serves as a recording paper deviation detecting unit, and forms a toner image on the photoconductor in accordance with the deviation of the recording paper detected by the deviation detecting unit. 2. The image forming apparatus according to claim 1.

9. A latent image is formed by imagewise exposing the photoconductor, and a toner image obtained by developing the latent image is
After being transferred by the transfer means to the first surface of the recording material conveyed from the paper supply unit and fixed by the fixing means, the recording material reversed upside down by the reversing means is again conveyed to the transfer area, and A new toner image formed on the recording material is transferred onto the second surface of the recording material by the transfer means, and is fixed to the fixing means and then discharged outside the apparatus. A determination unit configured to determine whether the recording material held by the paper supply unit can form an image on both of the first surface and the second surface, and the recording unit holding the recording material by the determination unit. An image forming apparatus comprising: a prohibition unit that prohibits the recording material held in the sheet feeding unit from being conveyed to the transfer unit when it is determined that the image cannot be formed on both sides of the image.

10. 10. The image forming apparatus according to claim 9, wherein the paper supply unit has a switching member for determining whether an image can be formed on both sides of the recording paper, and the determination by the determination unit is switching by the switching member. .

11. The image forming apparatus according to claim 9, wherein the determination by the determination unit is a determination by a detection unit that detects whether an image can be formed on both sides of the recording material in the sheet feeding unit.

[12] The image forming apparatus according to claim 9, further comprising an operation display unit, wherein the determination by the determination unit is an input from the operation display unit.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the image forming apparatus of the present invention is applied to a digital electrophotographic copying machine will be described below with reference to the drawings, but the present invention is not limited to this. .

First, an overall configuration and a schematic process of the copying machine will be described with reference to FIG. 1 which is a schematic sectional view of the copying machine.

In the copying machine of this embodiment, an automatic document feeder 1 is provided at the top of the copying machine main body, and an image reading device 2, an image forming section 3, a paper feeding section 4, and a transport path 5 are provided in the copying machine main body. , And a discharge / reversal unit 6.

The automatic document feeder 1 is provided at an upper portion of a copying machine main body, feeds out documents one by one, conveys them to an image reading position of the document, and discharges the document after the image reading. The automatic document feeder 1 includes a document table 11 on which a document is placed, a document separation unit 12 for separating the documents placed on the document table 11 one by one, and transports the documents separated by the document separation unit 12. Document feeder 13, a document discharger 14 for discharging the document conveyed by the document conveyer 13, a document discharge table 15 for receiving and placing the document discharged by the document discharger 14, and images on both sides of the document. And a document reversing unit 16 for reversing the front and back of the document when reading the document.

A plurality of documents placed on the document table 11 are separated by a document separation unit 12 and are conveyed one by one. The document separated and conveyed by the document separation unit 12 is conveyed by the document conveyance unit 13, and the image of the document is read through the slit 21 by the image reading device 2 provided below. The scanned document is
The document is discharged onto a document discharge table 15 by the document discharge unit 14. By the way, when scanning images on both sides of a document,
The original whose front image has been read is turned upside down by the original reversing unit 16, conveyed again by the original conveying unit 13, and the image reading unit reads the image of the back surface of the original through the slit 21. . Then, the document from which the image on the back surface has been read is discharged by the document discharge unit 14 onto the document discharge table 15. Such a process is repeated for the number of originals placed on the original placing table 11, and an image of the original is read.

Further, the automatic document feeder 1 is integrally foldable, and when the automatic document feeder 1 is raised to open the platen glass 22, the original is directly placed on the platen glass 22. It is configured so that it can be placed. In the present embodiment, the image of the original is read while the original is transported by the original transport unit 13, but the original transported by the original transport unit 13 is stopped on the platen glass 22. It may be configured to read an image above.

The image reading device 2 is a means for reading an image of a document and obtaining image data, and is provided at an upper part in the main body of the copying machine. The image reading device 2 includes a slit 21 which is a slit-shaped opening for reading an image of a document being conveyed by the document conveying unit 13 of the automatic document feeder 1, and a document table for directly placing the document. A certain platen glass 22, a lamp 2 which is a light source for irradiating a document with light
31 and a first mirror 232 that reflects light reflected from the document
And a second mirror 241 that reflects light from the first mirror unit 23,
A V mirror unit 24 integrating a mirror 242,
An imaging lens 25 which is an imaging unit for imaging reflected light from an original on the slit 21 or the platen glass 22 on the CCD 26, and a light image formed by the imaging lens 25 is photoelectrically converted into image data. And a line-shaped CCD 26 which is an image reading unit for obtaining the following.

When reading the original fed by the automatic original feeder 1 with the image reading device 2, the first mirror unit 23 and the V mirror unit 24, as shown in FIG. Are located below the slit 21. The lamp 231 irradiates the document conveyed on the slit 21 by the document conveyer 13 with light, and the light reflected from the document is reflected by the first mirror 232, the second mirror 241, the third mirror 242, and the imaging lens. The light is incident on the CCD 26 via the light source 25. The CCD photoelectrically converts incident light to read an image of a document in the main scanning direction (a direction perpendicular to the paper surface in FIG. 1). On the other hand, since the document is moved in the sub-scanning direction by the document conveying unit 13, The entire image can be read. The image data read by the CCD 26 is appropriately subjected to image processing, and supplied to a laser writing system 33 which is an exposure unit described later.

When an original is directly placed on the platen glass 22, the first mirror unit 23 and the V mirror unit 24 are moved along the platen glass to the right in FIG. An image on a document can be read.

The image forming section 3 is a means for forming an image on a recording sheet which is a sheet-like recording material conveyed at a predetermined process speed Vp based on the image data obtained by the image reading section 2. is there. Image forming unit 3 of the present embodiment
Is for forming an image using an electrophotographic process. The image forming unit 3 is based on a photosensitive drum 31 (photoconductor) having a photoconductive photosensitive layer and carrying a toner image, a charger 32 for uniformly charging the photosensitive drum 31, and image data read by the CCD 26. A laser writing system 33 that imagewise exposes the photosensitive drum 31 with a laser beam to form a latent image; a developing device 34 that develops the latent image on the photosensitive drum 31 to form a toner image; A transfer unit 35 (transfer unit) that transfers the toner image formed on the drum 31 to a recording paper (recording material) that is conveyed, and a separation unit that separates the recording paper on which the toner image has been transferred from the photosensitive drum 31 The image forming apparatus includes a device 36, a cleaning unit 37 for removing the toner remaining on the photosensitive drum 31 after the transfer, and a fixing unit 38 (fixing unit) for fixing the toner image on the recording paper. Around the photosensitive drum 31, a charger 32, a laser writing system 33, a developing unit 34, a transfer unit 35, a separator 36, and a cleaning unit 37 are arranged.

The photosensitive drum 31 is rotated in a direction indicated by an arrow by a drive unit (not shown), and is uniformly charged by a charger 32. The photosensitive drum 31 is exposed in synchronism with a leading end of a recording paper conveyed from a registration roller 56 described later. The started latent image formation by the laser writing system 33 and development by the developing device 34 are performed, and a toner image based on the image data read by the CCD 26 is formed. The formed toner image is transferred by the transfer unit 35 to a recording sheet that is separately conveyed. The recording paper to which the toner image has been transferred is separated from the photosensitive drum 31 by the separator 36 and is conveyed to the fixing unit 38, where the toner image is fixed on the recording paper by the action of heating and pressing. On the other hand, the photosensitive drum 31 on which the toner image has been transferred to the recording paper continues to rotate, and the cleaning unit 37 removes the toner remaining on the photosensitive drum 31 and is used for the next image formation.

In this embodiment, the photosensitive drum 31
In the vicinity of the photosensitive drum 31 between the photoconductor drum 31 and the registration roller 56, a pre-drum conveyance roller 39 that conveys the recording paper sent out from the registration roller 56 is provided. I have. Separator 3
In order to convey the recording paper separated by the separator 36 between the fixing unit 38 and the fixing unit 38, a conveying roller (unsigned) and a belt (unsigned) for supporting and conveying the back side of the recording paper are used. Provided.

The paper feed unit 4 is a paper feed unit that holds a plurality of recording papers in a stacked state. In the present embodiment, a plurality of paper feed units 4, namely, a first paper feed unit 4A, a second paper feed unit 4
B, and a third paper feed unit 4C.
4C are arranged below the image forming unit 3 in multiple stages. As a material of the recording material stored in the paper feed units 4A to 4C, there are various media such as OHT in addition to recording paper such as plain paper and recycled paper. Further, among recording materials of various materials, there are various types, such as backing paper and special paper, which can form an image on only one side, and those which can form an image on both sides.

The transport path 5 is a part of the transport section that transports the recording material from the paper feed section 4 to the image forming section 3, and each of the paper feed sections 4 A
To 4C can be conveyed to the image forming unit 3.

The discharging / reversing section 6 discharges the recording paper, on which the image has been formed by the image forming section 3, onto the recording paper conveyed by the conveying path 5, or reverses the recording paper. This is a means for re-conveying to the transfer area 31. The discharge / reverse unit 6 discharges the recording paper on which the toner image has been fixed from the fixing unit 38. The fixing discharge roller 61 discharges the recording paper discharged by the fixing discharge roller 61 as it is. A switching unit 62 that switches the transport path between when the paper is ejected after being discharged or when the paper is transported again to the transfer area to form an image on the back surface, a discharge roller 63 for discharging the recording paper outside the machine, and to the transfer area. Reversing unit 6 as reversing means for reversing the front and back of the recording paper conveyed again
5, and a re-sending section 66 for re-conveying the recording paper inverted by the reversing section 65 to the image forming section 3.

When the recording paper on which an image has been formed by the image forming section 3 is to be discharged as it is, that is, with the image-formed side facing upward, the switching section 62 is switched to the position shown by the dashed line in FIG. Roller 61, discharge roller 63
Is discharged to the sorter 64 (outside the machine). The sorter 64 has ten paper discharge trays 64a, and the recording paper P on which the image has been formed can be classified and discharged into each paper discharge tray 64a. In addition, the recording paper on which the image is formed is turned upside down and discharged, that is,
In the case of discharging the image with the image formed side down, the switching unit 62 is switched to the position shown by the solid line in FIG. 1 and the recording paper conveyed by the fixing discharge roller 61 is once conveyed in the direction of the reversing unit 65. Then, after the recording paper passes through the switching unit 62, the conveyance direction is reversed, and the recording paper is discharged to the sorter 64 by the discharge roller 63. On the other hand, when forming an image on the back side of the recording paper, the switching unit 62 is switched to the position shown by the solid line in FIG. 1 and the recording paper transported by the fixing discharge roller 61 is transported in the direction of the reversing unit 65. By performing switchback at 65, the front and back are reversed, and the sheet is conveyed to the retransmission unit 66.

The line sensor 220 as the measuring means of the present invention is disposed between the registration roller 56 and the transport roller 39. This position is immediately before the toner image is transferred onto the recording paper P, and the dimension can be measured immediately before the image is formed on the second surface via the fixing unit 38, the reversing unit 65, and the re-sending unit 66, and the accurate shrinkage ratio is obtained. Is preferred. In addition, since the measurement before and after fixing by the fixing device 38 can be performed at one place and by one measuring unit by setting the position, it is preferable from the viewpoint of cost and error of each measuring unit. . Further, as will be described later, the line sensor 220 not only guarantees an accurate toner image magnification of the second surface as a measuring unit, but also functions as a deviation detecting unit at the same time.
A toner image can be formed at an accurate position on the recording paper P, and a synergistic effect can be expected in forming a precise image.

Next, the first to eighth aspects of the present invention will be described with reference to FIG.
The description will be made with reference to FIGS. FIG. 2 is a view showing a conveying section from the registration roller 56 to the photosensitive drum 31 in the copying machine shown in FIG.
FIG. 3 is a block diagram showing an example of an electrical configuration of a laser writing system 33;

In FIG. 2, reference numeral 110 denotes a CPU as control means for controlling the operation of each part of the copying machine. In the present invention, the contraction rate is calculated from the measurement result of the length and width of the recording paper P by the line sensor 220. Then, a toner image is formed on the photoconductor at a magnification corresponding to the contraction rate by controlling the writing speed of the laser writing system 33 and controlling the rotation speed of the photoconductor drum 31 or the transport roller.

That is, the line sensor 2 as a measuring means
Reference numeral 20 denotes the time of image formation on the first surface (before fixing by the fixing unit).
And measuring a vertical dimension, which is a length in the transport direction of the recording paper P, and a horizontal dimension, which is a length in a width direction orthogonal to the transport direction, of the second surface during image formation (after fixing by the fixing unit). From the result, the CPU 110 calculates the contraction rate. And C
The PU 110 controls the photosensitive drum 31 in accordance with the contraction rate.
It controls the upward exposure speed (changes the magnification of the horizontal dimension), and adjusts the photosensitive drum 31 or the transport roller (registration roller 5).
6, the rotation speed of the transport rollers 39 and the like is controlled (the magnification of the vertical dimension is changed), and the magnification of the toner image is changed.

In the embodiment of the present invention, the line sensor 220 is a CCD or CIS or the like, which not only measures the vertical size and the horizontal size of the recording paper P but also serves as a deviation detecting means when the recording paper P is transported. Also, the detection of the deviation is performed.
For example, the deviation at the time of conveyance may be a deviation (longitudinal deviation) in the conveyance direction or a conveyance direction because a toner image to be formed in the middle of the recording paper P has poor conveyance accuracy to the transfer area of the recording paper P. The image is formed at an undesired position due to a deviation (lateral deviation) in a direction perpendicular to the direction or a deviation from the axis in the transport direction (bending deviation), and there is a problem in high-precision image formation. The CPU 110 determines the vertical shift, the horizontal shift and the bending shift by detecting at which position or at what timing of the line sensor 220 the leading edge of the conveyed recording paper P passes by the line sensor 220. You can do it. The CPU 110 controls the recording position by the laser writing system 33 in accordance with the deviation information, and forms a toner image on the photosensitive drum 31 so that the conveyance accuracy of the recording paper P to the transfer area is low. Thus, the toner image can be transferred to an accurate position. As described above, immediately before the transfer area, when the toner image is transferred onto the first surface of the recording paper P, the transport path from the paper feeding unit 4 to the transfer area and the second surface of the recording paper P When one line sensor is provided in a portion overlapping with the conveyance path from the re-sending section 66 to the transfer area when transferring the toner image to the toner image, the correction of the shrinkage ratio as the measuring means in the present invention and the deviation detecting means , It is possible to perform both of the displacement correction, and it is possible to achieve efficient and accurate image formation as a mechanical configuration.

Reference numeral 120 denotes the displacement of the exposure speed and the exposure position in the main scanning direction (horizontal direction on the recording paper P) on the photosensitive drum 31 in accordance with the magnification determined by the CPU 110 and the correction of the deviation during the conveyance of the recording paper P. This is a writing control unit that performs control to cause the writing to be performed. Reference numeral 33 denotes a laser writing system for writing an image on the photosensitive drum 31 with a laser beam under the control of the writing control unit 120.

The processing section 100 including the CPU 110, the writing control section 120, and the laser writing system 33 is arranged on a main circuit board of the image forming apparatus.

Reference numeral 210 denotes a sensor drive clock generator for generating a sensor drive clock for driving the line sensor 220.
It is configured to measure the horizontal and vertical dimensions of the recording paper P and detect a deviation. Reference numeral 220 denotes a line sensor driven by the sensor driving clock, which includes an LED light source 220a serving as a light emitting unit and a light receiving unit 220b.

It is desirable to use a red LED as the LED light source 220a because the response is improved. The light receiving section 22
0b can use the reading sensor of the facsimile machine. The LED light source 220a and the light receiving unit 22
The light emitting element and the light receiving element do not have to correspond to 0b one by one.

Reference numeral 230 denotes a sample and hold circuit which samples and holds the output of the line sensor 220 in synchronization with the sensor drive clock. Reference numeral 240 denotes a comparator for comparing the hold result of the sample hold circuit 230 with a predetermined value (recording paper detection level). Reference numeral 250 denotes a counter for counting the sensor drive clock when the output of the comparator 240 is in a predetermined state. Reference numeral 260 denotes a serial transmission unit that converts the count result of the counter 250 into predetermined serial data and transfers the data by serial communication.

The sensor drive clock generator 21 described above
0, sample hold circuit 230, comparator 24
0, the counter 250, and the serial transmission unit 260 are arranged near the line sensor 220.
M1 is a drive motor for driving the photosensitive drum 31; M2 is a drive motor for driving a registration roller 56 and a conveyance roller as conveyance means for the recording paper P;
The drive control is performed while the rotation speed is changed by the control signal from 10.

FIG. 3 is a timing chart showing the operation timing of each component in the duplex mode and the measurement mode of the copying machine described with reference to FIGS.

First, a double-sided mode is selected from an operation display unit such as a liquid crystal touch panel display of a copying machine, and a measurement mode as a lower layer setting is selected (1). The measurement mode is a mode of precise image formation in which the contraction rate of the recording paper after passing through the fixing means is calculated in the double-sided mode and reflected on the formation of the toner image on the second surface. Therefore, there may be a selection of a duplex mode other than the measurement mode.

In the present embodiment, it is set to output three sheets on which images are formed on both the first and second sides of the recording paper. Next, when the start button of the copying machine is pressed, image formation in the measurement mode is started (2). Since the desired number of recording sheets on which an image is to be formed is three, one is used only for calculating the shrinkage ratio before that, and one recording sheet for measurement without toner image transfer is added. Is transferred to the transfer area (3).

The first sheet at the top is for measurement which is used only for measuring the vertical and horizontal dimensions and calculating the shrinkage ratio. 1
The first recording sheet P (Table 1) is conveyed to the transfer area with the first surface (Table 1) facing the photosensitive drum 31. The line sensor 220 disposed between the registration roller 56 and the conveyance roller 39 , The vertical dimension T1 is detected from the transit time from the front end to the rear end, and the horizontal dimension L1 from the left end to the right end is detected (4, 5). The vertical dimension T1 and the horizontal dimension L1 are dimensions before being fixed by the fixing unit.

The first surface of the first sheet (Table 1), the first surface of the second sheet (Table 2), the first surface of the third sheet (Table 3), and the first surface of the fourth sheet (Table 4) Drum 31 when is passed through the transfer area
Is the rotation speed A during normal image formation,
The drive motor M1 of the photosensitive drum 31 is driven to rotate the photosensitive drum 31 at that speed (6). Also,
Horizontal writing speed of laser writing system 33 (main scanning speed)
Is controlled by the writing control unit 120 so as to be performed at the main scanning speed a during normal image formation (7).

In the transfer area, Table 1 shows that the recording paper is dedicated to measurement, so that the toner image is not transferred, and the paper is conveyed to the fixing unit 38 as a blank paper. In Tables 2, 3, and 4, the toner image is transferred to the fixing device 38 in the transfer area, respectively.

Next, the recording paper contracted by passing through the fixing device 38 is turned upside down by the reversing section 65 and passes through the re-feeding section 66 so that the second surface faces the photosensitive drum 31 this time. Is transported again toward the transfer area (3).

When the second surface (back 1) of the first sheet is conveyed from the re-sending section 66 and passes through the line sensor 220, the vertical and horizontal dimensions after being fixed by the fixing means are measured in the same manner as described above. Is done. At this time, the vertical dimension is T2 and the horizontal dimension is L2.
(4, 5).

From the longitudinal dimension T1 and lateral dimension L1 before being fixed by the fixing means and the longitudinal dimension T2 and lateral dimension L2 after being fixed, the contraction rate is calculated by the CPU serving as the control means. The contraction rate in the vertical direction is T2 / T1, and the contraction rate in the horizontal direction is L2 / L1. The first sheet after the measurement of the vertical and horizontal dimensions after the fixing is completed, passes through the transfer area as it is, without transferring the toner image as it is, and is discharged to the discharge tray 1 via the fixing means (8). The first sheet is a sheet dedicated to measurement, and is not counted as an image formed. Therefore, the total counter is not counted (1
0).

On the other hand, the second surface (back 2) of the second sheet, the second surface (back 3) of the third sheet, and the second surface (back 4) of the fourth sheet are formed at a magnification corresponding to the shrinkage ratio. In order to transfer the toner image thus formed, image formation is performed at a transfer speed and a writing speed corresponding to the calculated contraction rate. That is, the rotation speed of the photosensitive drum 31 is obtained by multiplying the rotation speed A at the time of transferring the toner image on the first surface by the longitudinal shrinkage ratio T2 / T1, and the rotation speed A × T2 /
The drive motor M1 is driven to be T1 (6). The main scanning speed of the laser writing system 33 on the photosensitive drum 31 is the main scanning speed a on the first surface and the lateral contraction rate L.
The writing control unit 120 controls the main scanning speed a × L2 / L1 by multiplying 2 / L1 (7). Then, under such control, the second, third, and fourth sheets are transferred with the toner image on the second surface thereof in the transfer area and conveyed to the fixing unit. Is discharged to a discharge tray 2 different from the first recording paper (9). Second, third,
Since the fourth sheet is an output on which a desired image has been formed, the total counter is counted as 1, 2, and 3 (10).
As the discharge tray 1 or 2, an appropriate one can be selected from the ten discharge trays described with reference to FIG.

As described above, in the measurement mode of the double-sided mode, the first sheet of the recording paper continuously conveyed is used only for obtaining the shrinkage rate, and the shrinkage rate is obtained on the first sheet. The second and subsequent toner images are formed at the magnification corresponding to the shrinkage ratio for the second and subsequent surfaces, and the first and second images are used only for determining the shrinkage ratio, and the second and subsequent images are formed. Are output to separate paper output trays, so that the user can obtain only desired image-formed output without performing subsequent sorting work. Further, since the first sheet is not counted by the total counter, there is an advantage that the number can be easily managed.

Next, the inventions of claims 9 to 12 will be described with reference to FIGS. FIG. 4 is a diagram showing a mode in which a switching member is provided in a paper feeding unit of a copying machine as a determination unit. FIG. 4A is a perspective view illustrating a state where one of the sheet feeding units is pulled out, and FIG. 4B is an enlarged view of a switching member of the sheet feeding unit.

In the figure, reference numerals 4A to 4C denote the first to third paper feeding units described with reference to FIG. Each of the three paper feed units is of a drawer type, and replenishes recording paper in the pulled-out state. In FIG. 4A, the third sheet feeding unit 4C
5 shows a state in which the user puts his hand on the handle 402 and pulls it out toward the user (in the direction of the white arrow). In this figure, no recording paper is stored. The third paper feed unit 4C has a cutout in a part of a paper feed tray 401 that holds a bundle of recording paper, and regulates the position of two adjacent sides of the recording paper in the cutout,
Rear end stopper 403 for fixing recording paper in place
, The back side regulating plate 404 is fitted. By changing the positions of the rear end stopper 403 and the back regulating plate 404, it is possible to hold recording sheets of various sizes in the sheet feeding unit.

Reference numeral 410 denotes a dial-type switching member as a discriminating means of the present invention. As shown in the enlarged view of FIG. 4B, the user manually rotates the switching member 410 to set a desired mode. In this drawing, a state in which the A4 size recording paper for which image formation is to be performed on only one side of backing paper or special paper or the like is set in the “A4 double-sided prohibited” mode so as to be stored in the third paper feeding unit 4C. Represents.

As described above, when the recording paper is replaced or replenished,
When the user pulls out the paper feed unit, the user only manually operates the switching member (determination means) provided in the paper feed unit to set the prohibition of the duplex mode. Can be prevented from being erroneously used for image formation in the duplex mode.

FIG. 5 is a block diagram showing a duplex mode inhibiting function of a copying machine having the switching member of FIG. 4 as a discriminating means. Components having the same reference numerals as those in the above-described drawings have the same meanings as those described above. Reference numeral 130 denotes an operation display unit such as a liquid crystal touch panel display provided in a place where the user of the copying machine can easily handle the user.
The paper feed drive unit drives a transport roller or the like that transports the recording paper held in the image forming unit 3 toward the image forming unit 3.

First, a double-sided mode is selected from the operation display unit 130 by a user input. CPU110
Stores information on whether or not the recording paper held in the paper supply unit can be used for image formation in the double-sided mode in advance by manual setting by the user of the switching member 410 as the paper supply unit determination unit. When image formation in the double-sided mode is possible, the CPU 110 outputs a control signal to each component, drives the paper feed drive unit 420 to move the recording paper of the paper feed unit to the image forming unit 3. After the image forming unit 3 forms an image on the first surface, the reversing unit 65 reverses the recording paper, and the image forming unit 3 forms an image on the second surface again. Then, control is performed so that the sheet is discharged to an appropriate discharge tray 64a.

On the other hand, if a recording sheet that cannot be used in the double-sided mode is held in
The selection unit 110 determines that the recording paper of the paper feeding unit cannot be used when the duplex mode is selected, and prohibits the feeding of the recording paper from the paper feeding unit. At this time, the CPU 110 has a function of a prohibition unit in the present invention. Then, when it is determined that the feeding of the recording paper from the paper feeding unit is prohibited, the operation display unit 130 is displayed to that effect, and the user is notified whether or not the image forming in the duplex mode is possible. Or, in another paper source,
If recording paper of the same size and capable of generating images in the duplex mode is held, the paper may be changed to paper from another paper supply unit.

FIG. 6 is a flowchart for judging whether or not the duplex mode of the copying machine having the switching member described with reference to FIGS.

First, the user inputs image forming conditions from the operation display unit and sets the conditions (S11). The conditions for image formation include the size of recording paper to be used, the image density, the number of sheets, the presence or absence of selection of a duplex mode, and the like. After setting the conditions,
The user presses a start button for image formation (S12).

Next, the CPU of the copying machine automatically sets a paper feeder for automatically selecting a paper feeder that holds recording paper meeting the setting condition S11 from among a plurality of paper feeders. It is confirmed whether or not there is (S13). If the paper feed unit automatic selection setting has not been made and the user has designated a paper feed unit in condition setting S11 (NO), step S111
Proceed to. If the paper feed unit automatic selection setting has been made (Y
ES), it is determined whether the duplex mode is selected in the condition setting S11 (S14). If the duplex mode has not been selected (NO), the process proceeds to step S17.

When the double-sided mode is selected, (Y
ES), information as to whether or not the recording paper held by each paper feed unit can form an image in the double-sided mode is acquired by the switching member serving as the discriminating means (S15). The paper supply unit that can perform the operation is selected (S16).

Next, the size information of the recording paper set in the condition setting S11 is obtained (S17). Step S
Among the paper feed units selected in step 16, the paper feed unit that holds the recording paper corresponding to the set recording paper size is selected (S1).
8).

Next, in step S19, if there is no corresponding paper feed unit (NO), it is determined that image formation cannot be performed under the set conditions, and the operation display unit or the like informs the operation display unit or the like that image formation cannot be performed. It is displayed and prompts the user to reset the conditions (S110).

If it is determined in step S19 that the corresponding paper feed unit exists (YES), then the paper feed unit
It is checked whether the recording paper required for image formation is held (S111). If there is no recording paper (NO), a message requesting replenishment of the recording paper is displayed on the operation display unit (S113). When the user completes the replenishment of the recording paper into the paper feeding unit (S114), the process is repeated from step S111 again. If there is a recording sheet (YES), image formation is performed according to the set conditions (S112).

FIG. 7 is a diagram showing an embodiment having a detecting means for detecting whether or not an image can be formed on both sides of a recording material in a paper feeding section of a copying machine as a determining means.

FIG. 7A is an overall sectional view of a copying machine having a detecting means in a paper feeding section. The same reference numerals in the drawing as those described above denote constituent members having the same meaning as described above. 52A and 53A, 52B and 53B, 52C and 53C
Is a transport roller of the first paper supply unit 4A, the second paper supply unit 4B, and the third paper supply unit 4C, respectively, and P is a recording paper. 43A, 4
Reference numerals 3B and 43C denote density sensors as detecting means of the respective sheet feeding units.

FIG. 7B is a partially enlarged view of the vicinity of the density sensor 43A of the first sheet feeding section 4A. The uppermost sheet is picked up from the bundle of recording papers P stacked and stored in the sheet feeding unit, and the transport roller 52A located immediately after the start of transport is picked up.
The density of the second surface (back surface) of the recording paper P is detected by the density sensor 43A provided at the intermediate point between the recording paper P and the intermediate point 53A. The density sensor 43A is not particularly limited as long as it can detect the density of the recording paper P, but is a photosensor or the like having a light emitting element and a light receiving element. The density of the second surface of the recording paper P detected by the density sensor 43A is higher than a density (back paper or the like) recognized as having a toner image or a density of a reference white paper by a certain value or more. In the case of density (special paper or the like), it is recognized that a recording paper on which an image should not be formed on the second surface, and image formation in the duplex mode is prohibited. When the duplex mode is selected from the operation display unit, if it is determined that the recording sheet of the paper feeding unit cannot form an image in the duplex mode, the rotation of the transport rollers 52A and 53A is stopped and the image forming unit 3 Is not transported (double-sided mode is prohibited). When the two-sided mode is prohibited, the operation display unit 1
30 is displayed to notify the user that image formation in the duplex mode is not possible. Alternatively, in a case where recording paper of the same size and capable of generating an image in the duplex mode is held in another paper feeding unit, the paper may be changed to paper feeding from the other paper feeding unit. .

In this embodiment, the density sensor 43A
Is located at an intermediate point between the transport rollers 52A and 53A, but may be a position that can be detected in a state where the recording paper P is stored in the paper feeding unit before the transport is started.

In the present embodiment, the density sensor is used as the detecting means. However, the present invention is not limited to this, as long as it is possible to actually determine whether images can be formed on both sides.

In the aspect in which the above-mentioned detecting means is provided in the sheet feeding section,
Since the copier can automatically determine whether or not image formation can be performed in the double-sided mode of the recording paper and can prohibit the image forming, the user can save time and effort in setting the type of recording paper, and the recording paper held in the paper feeding unit can be used. It is possible to efficiently prevent a problem of being used in the double-sided mode by mistake.

FIG. 8 is a block diagram showing a double-sided mode inhibition function of a copying machine having the density sensor (detection means) of FIG. 7 as a determination means. Components having the same reference numerals as in the above-described drawings have the same meanings as those described above. Reference numeral 43 denotes a density sensor as detecting means for detecting whether or not a recording sheet provided in the sheet feeding unit can form an image in a duplex mode.

When the duplex mode is selected by the user from the operation display unit 130, the CPU 110 selects an appropriate paper feed unit from among the paper feed units that hold recording paper of a size according to the set conditions. . Then, the density sensor 43 is operated to detect whether or not an image can be formed in the double-sided mode on the recording sheet held by the sheet feeding unit. At this time, if necessary, the sheet feeding drive unit 420 is driven to start feeding of the recording sheet from the sheet feeding unit, and the recording sheet is moved to a position where the density sensor 43 can detect the sheet. CPU11
0 indicates that the CPU 110 outputs a control signal to each component when the detection information from the density sensor 43 as the detection means determines that image formation in the double-sided mode is possible. 420 is driven to convey the recording paper held in the paper feed unit toward the image forming unit 3. In the image forming unit 3, after performing image formation on the first surface of the conveyed recording paper, the reversing unit 65 inverts the front and back of the recording paper. Control is performed so that the image is formed and discharged to an appropriate discharge tray 64a.

On the other hand, if it is determined that the recording paper which cannot be used in the duplex mode is held, the CPU 1
Reference numeral 10 prohibits the feeding of recording paper from the paper feeding unit. At this time, the CPU 110 has a function of a prohibition unit in the present invention. Then, when the double-sided mode is prohibited, the operation display unit 130 displays a message to that effect, and notifies the user whether or not image formation in the double-sided mode is possible. Alternatively, in a case where recording paper of the same size and capable of generating an image in the duplex mode is held in another paper feeding unit, the paper may be changed to paper feeding from the other paper feeding unit. .

FIG. 9 is a flowchart for judging whether or not the duplex mode of the copying machine having the density sensor (detecting means) described with reference to FIGS. 7 and 8 as the judging means.

In this flowchart, the condition setting S11 described in the flowchart of FIG. 6 is based on the assumption that the double-sided mode is selected (S21), and the specific paper feeding unit is designated and selected by the user. This is simplified assuming the case (or assuming a copying machine having only one sheet feeding unit).

First, a double-sided mode is selected by the user in setting image forming conditions (S21). The user presses the start button to start image formation (S2
2).

Next, the recording paper of the selected paper feed unit is checked by a density sensor as a detecting means disposed in the paper feed unit to determine whether image formation in the duplex mode is possible or not. Is detected (S23).

If the paper is back paper or special paper and the duplex mode cannot be performed (NO), the mode is switched to the simplex mode and image formation is performed (S26). When the double-sided mode is prohibited, a display indicating that the double-sided mode is disabled may be displayed on the operation display unit without switching the single-sided mode, and the user may be prompted to reset the conditions.

When images can be formed on both sides (YE
S), image formation in the duplex mode is executed according to the set conditions (S25).

FIG. 10 is a diagram showing an example of a setting screen of the operation display unit in a mode in which the determination by the determination unit is performed by input from the operation display unit of the copying machine.

FIG. 10A shows a basic screen of the operation display section 130 constituted by a liquid crystal touch panel display. Selection of copy mode (COPY MODE key), image formation from single-sided document (1) to both sides (2), selection of image density (COPY DENSITY key), magnification setting (LENS MODE key), selection of recording paper size (P
APER SIZE key) is displayed.

When the user presses the PAPER SIZE key 131, a lower layer screen as shown in FIG. 10B is displayed. The copier has two paper feeding units for holding B4 size recording paper and four paper feeding units for holding A4 size recording paper.
It indicates that there is one. Of the six keys, the paper feed unit indicated by the lower right A4 size key 132 holds recording paper such as backing paper or special paper that cannot form images in the duplex mode. In order to set the recording paper of the set to prohibit image formation in the duplex mode, first,
Press the size key 132. Then, the pressed key darkens as indicated by 132a in FIG. When the A4 size key 132a is pressed again, the display changes to a display that indicates "double-sided inhibition" as indicated by 132b in FIG. A4 size key 1 displaying this double-sided prohibition
32b, when pressed again, the display of double-sided prohibition disappears, and FIG.
It returns to the display of 132a of (c).

According to the above-described method, the user sets in advance the sheet feeding unit for which image formation in the double-sided mode is to be prohibited from the operation display unit 130. When the double-sided mode is subsequently selected, the setting is performed. The feeding of the recording sheet from the fed sheet feeding unit to the transfer means is not performed, or the mode can be switched to the one-sided mode image formation.

After the setting by the input from the operation display unit 130 is completed, the control is the same as that of the copying machine in which the switching unit of the sheet feeding unit described with reference to FIGS. The flowchart is omitted.

[0092]

In the duplex mode, the enlargement ratio of the toner image on the front and back surfaces does not change irrespective of the type of the recording material, so that the user is not required to perform labor such as manual work, and the recording is not desired to form an image on both sides. It is possible to provide an image forming apparatus in which the image formation in the duplex mode is prohibited for the recording material, and the recording material is not wasted.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a copying machine.

FIG. 2 is a block diagram illustrating an example of an electrical configuration of a transport unit, a line sensor (measuring unit), and a laser writing system in the copying machine of FIG.

FIG. 3 is a timing chart showing the operation timing of each component in the duplex mode of the copying machine shown in FIGS. 1 and 2 and in the measurement mode.

FIG. 4 is a diagram showing a mode in which a switching member is provided in a sheet feeding unit as a determination unit of the copying machine in FIG. 1;

FIG. 5 is a block diagram illustrating a double-sided mode prohibition function of the copying machine having the switching member of FIG. 4 as a determination unit.

FIG. 6 is a flowchart for determining whether or not a duplex mode of a copying machine having the switching member described in FIGS. 4 and 5 as a determination unit;

FIG. 7 is a diagram showing an embodiment having a detection unit for detecting whether images can be formed on both sides of a recording material in a paper feeding unit of the copying machine as a determination unit of the copying machine of FIG. 1;

8 is a block diagram showing a duplex mode prohibition function of a copying machine having the density sensor (detection unit) of FIG. 7 as a determination unit.

FIG. 9 is a flowchart for determining whether or not the duplex mode of the copying machine having the density sensor (detection unit) described in FIGS. 7 and 8 as a determination unit;

FIG. 10 is a diagram illustrating an example of a setting screen of the operation display unit in a mode in which the determination by the determination unit is performed based on an input from the operation display unit of the copying machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 automatic document feeder 2 image reading device 3 image forming unit 4 paper feeding unit 5 transport path 6 discharge / reversal unit 31 photoconductor drum 33 laser writing system 43 density sensor 52, 53 transport roller 56 registration roller 64a paper ejection tray 65 Reversing unit 66 Retransmission unit 110 CPU 130 Operation display unit 131 PAPER SIZE key 132 A4 size key 220 Line sensor 401 Paper feed tray 410 Switching member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (reference) G03G 15/00 106 G03G 15/00 530 3F053 530 B41J 3/00 S 3F100 21/14 G03G 21/00 372 ( 72) Inventor Hiroyuki Watanabe 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (72) Inventor Kenji 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation F-term (reference) 2C062 RA06 2H027 DA38 DA45 DC00 DC10 DE02 DE07 DE10 ED04 ED17 ED22 FA13 FB12 HA07 2H028 BA06 BA14 BB00 BB06 BB08 2H072 AA16 AA23 AA32 AB12 CB01 CB03 FC02 3F048 AA03 AB01 BA07 BB02 BC04 CA03 CC11 DA06 DB12 DC14 EB02 EB40 3F053EA01 EC04 DA08 EA05 EA11

Claims (12)

[Claims] 1. A latent image is formed by imagewise exposing a photoconductor, and a toner image obtained by developing the latent image is transferred to a first surface of a recording material by a transfer unit. After fixing, the recording material, which has been turned upside down by the reversing means, is again conveyed to the transfer area, and a new toner image formed on the photoreceptor is transferred to the second area of the recording material by the transfer means.
An image forming apparatus capable of forming an image in a double-sided mode, wherein the recording material is fixed to the recording material before and after the recording material is fixed by the fixing device. Measuring means for measuring a longitudinal dimension and a lateral dimension of the recording material; fixing means for the recording material from a longitudinal dimension and a lateral dimension before and after fixing of the recording material by the fixing means measured by the measuring means. Control means for calculating a shrinkage rate according to the formula (1), and forming a toner image at a magnification corresponding to the shrinkage rate on the photoreceptor. For the second and subsequent recording materials, the toner image transferred to the first surface is formed on the photosensitive member by normal image formation, and is transferred to the second surface of the same recording material. The toner image
Forming a toner image on the photoconductor at a magnification corresponding to the shrinkage calculated on the first recording material, and distinguishing the first recording material from the second and subsequent recording materials; An image forming apparatus having a measurement mode for discharging to the outside. 2. A printing apparatus comprising: a plurality of discharge trays, wherein the first recording material is discharged to a first discharge tray, and the second and subsequent recording materials are discharged to a second discharge tray. The image forming apparatus according to claim 1, wherein: 3. A total counter for counting and displaying the number of recording materials discharged out of the apparatus, wherein the first recording material is not included in the count of the total counter. Item 3. The image forming apparatus according to item 1 or 2. 4. The image forming apparatus according to claim 1, wherein the measuring unit that measures the lateral dimension of the recording material is a CCD or a CIS. 5. A recording device for measuring a lateral dimension of the recording material, comprising: a conveyance path from a paper feeding unit to the transfer area when a toner image is transferred onto a first surface of the recording material; The image forming apparatus according to any one of claims 1 to 4, wherein a transfer path from the re-sending section to the transfer area when the toner image is transferred to the second surface of the material overlaps with the transfer path. The image forming apparatus as described in the above. 6. The apparatus according to claim 1, wherein said measuring means for measuring the longitudinal dimension of said recording material measures said longitudinal dimension by measuring a passage time of said recording material. An image forming apparatus according to claim 1. 7. Exposure for forming a latent image on the photoconductor is performed by scanning and exposing the photoconductor in a horizontal direction with a laser beam while moving the photoconductor in a vertical direction. The formation of the toner image in accordance with the above shrinkage ratio is performed by changing the magnification of the vertical dimension by changing the moving speed of the photoconductor and changing the magnification of the horizontal dimension by changing the speed of the scanning exposure. The image forming apparatus according to claim 1, wherein: 8. The apparatus according to claim 1, wherein said measuring means also functions as a recording paper deviation detecting means, and forms a toner image on said photosensitive member in accordance with the deviation of said recording paper detected by said deviation detecting means. The image forming apparatus according to any one of claims 1 to 7. 9. A latent image is formed by imagewise exposing a photoconductor, and a toner image obtained by developing the latent image is formed on a first surface of a recording material conveyed from a paper feeding unit. After being transferred by the transfer unit and fixed by the fixing unit, the recording material reversed upside down by the reversing unit is transported again to the transfer area,
A new toner image formed on the photoreceptor is transferred to the second surface of the recording material by the transfer unit, fixed by the fixing unit, and then discharged outside the apparatus, thereby enabling image formation in a duplex mode. The image forming apparatus further includes a determination unit configured to determine whether the recording material held by the paper supply unit can form an image on both the first surface and the second surface. The image processing apparatus according to claim 1, further comprising a prohibition unit configured to prohibit transport of the recording material held in the sheet feeding unit to the transfer unit when it is determined that the held recording material cannot form an image on both sides. Forming equipment. 10. The image forming apparatus according to claim 9, further comprising a switching member for determining whether an image can be formed on both sides of the recording paper in the paper feeding unit, wherein the determination by the determining unit is switching by the switching member. An image forming apparatus according to claim 1. 11. The image forming apparatus according to claim 9, wherein the determination by the determination unit is a determination by a detection unit that detects whether an image can be formed on both sides of a recording material in the sheet feeding unit. 12. The image forming apparatus according to claim 9, further comprising an operation display unit, wherein the determination by the determination unit is an input from the operation display unit.