JPS61235828A - Copying machine - Google Patents

Abstract

PURPOSE:To easily align the front end of a paper to the front end of image formation by shifting a lens array in exposure position based upon variable power from a transfer position according to the variable power. CONSTITUTION:An original platen 24 is moved in variable power mode at a speed vo=v/a, where (a) is magnification and (v) is the moving speed of a photosensitive body 1. For example, when a reduced copy is taken, the platen 24 is moved at a speed faster than in unmagnification copying operation. Here, the time aDELTAl/v from when the original platen 24 is moved and a reed switch 32 is turned on to when the front end 25 of an original reaches a scanning start position 30 is DELTAl/v-aDELTAl/v earlier than the time aDELTAl/v when the front end of the original reaches the position 30 in unmagnification copying operation. For the purpose, the distance l2 between an exposure position 3-1 in reduction mode and an exposure position 3-2 in unmagnification mode is set to DELTAl-aDELTAl so that the exposure position 3-1 is at a longer distance to a transfer position 9 than the exposure position 3-2. Consequently, the front end of the paper is easily aligned to the front end of image formation on a recording medium.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to an electrophotographic copying apparatus that uses a convergent light transmitting array as an optical means for projecting a copy original onto a recording medium, and is capable of producing only full-size copies. <Prior art> In an electrophotographic copying machine, a recording medium having a photoconductive layer is uniformly charged to a specific polarity, and an optical image of a copy document is By projecting onto the recording medium, an electrostatic latent image corresponding to the copy document is formed on the recording medium. As a method for projecting (exposing) a copy original onto a recording medium, there is a method in which an imaging lens having a focal length f is provided and a reflected optical image of the copy original is passed through the lens and exposed onto the recording medium. In this case, in order to expose an image of the copy original at the same size on the recording medium, it is necessary to set a distance of 2f as the optical path length from the lens to the copy original. Furthermore, the optical path length between the lens and the recording medium must also be set to 2f. When projecting the image of a copy document onto a recording medium in this way, a total optical path length of 4f is required. In order to obtain this optical path length, a large number of reflecting mirrors are arranged at appropriate positions. Therefore, according to the optical means using the imaging lens as described above, since a considerable optical path length is required, the entire optical unit is As a result, miniaturization and weight reduction of copying devices are restricted to some extent.

Therefore, recently, there is a convergent light transmitting array (hereinafter referred to as a lens array) as a means for projecting an image. This lens array forms an image at a predetermined position by allowing the reflected light image from the document to enter from one end and exit from the other end. That is, the lens array is placed between the recording medium and the copy document. By using this lens array, the considerable optical path length required when using a normal lens is not required, and the lens array only needs to be placed with a small distance between the copy document and the recording medium. , it becomes possible to significantly downsize the copying device.

On the other hand, variable magnification copying was easily possible using optical means using ordinary lenses. However, in those that use a lens array, the magnification of the lens array itself is determined, and it is impossible to perform variable-magnification copying other than this magnification (for example, equal magnification). Therefore, apart from a lens array with a specific magnification, for example, an equal magnification, a variable magnification lens array is arranged in parallel, and by selectively switching between these lens arrays, it becomes possible to copy at the same magnification or at a variable magnification. Japanese Patent Application Laid-Open No. 59-1625 made it possible to perform variable magnification copying using such a lens array.
It is described in Publication No. 69, etc. According to this apparatus, since the positions at which the original image is exposed on the recording medium are different, timing control for feeding the transfer material to the transfer position facing the recording medium becomes complicated. Therefore, if the position at which the original image is exposed to the recording medium is made to be the same for all lens arrays, the time required for the leading edge position of the recording medium to reach the transfer position will always be constant. is always rotated at a constant speed regardless of when the magnification is changed, and
This allows the timing of feeding the transfer material to be constant,
Its handling becomes easier. An example of this is JP-A-5
9-116732 and JP-A No. 59-125717, etc. According to the above-mentioned JP-A-59-116732, the imaging position on the recording medium by each lens array (
Each lens array is arranged at an angle so that the exposure positions (exposure positions) coincide with each other. In this case, the lens arrays are not arranged in parallel, the angle of incidence on one end surface is different, and the starting end for scanning the document is also different, resulting in a large difference in the amount of exposure light on the recording medium.

Further, if the scanning start ends in document scanning are different, not only will the illuminance difference due to the illumination device become large, but if the timing of feeding the transfer material is controlled on the document scanning means side, the control becomes complicated.

On the other hand, according to Japanese Patent Application Laid-Open No. 59-125717, not only the exposure positions of the recording medium are made to coincide, but also the scan start ends of the originals are made to coincide with each other. If this is the case, even if the conveyance timing of the transfer material is adjusted in the document scanning section, the exposure positions will all be the same, so it is thought that the control will be extremely simple. however,
According to this Japanese Patent Application Laid-Open No. 59-125717, a large number of mirrors are required, making optical path adjustment extremely troublesome. Furthermore, since the number of reflecting mirrors increases, the cost increases.

Purpose> The present invention realizes alignment of the leading edge of a transfer material and the image forming leading edge of a recording medium with a simple configuration in an electrophotographic copying apparatus having a constant magnification lens array and a plurality of variable magnification lens arrays. The purpose is to Another object of the present invention is to simplify and reduce the cost of the configuration of the exposure apparatus itself in each lens array.

<Embodiment> The figure is a sectional view showing the main part configuration of a copying apparatus according to the present invention. In the figure, 1 is a recording medium having a photoconductive layer, for example, an endless photoreceptor formed in the shape of a belt; 2 is a corona discharger that uniformly charges the surface of the photoreceptor to a specific polarity; 11.
:L2.3 is the exposure position at which the original image is projected onto the photoreceptor 1 at each copying magnification. Photoreceptor 1 is 3
The books are stretched between rolls 4a + 4b and 4C, and are always transported in the direction of the arrow at a constant speed V by driving the rolls 4a. When an image of a copy document is projected onto the photoreceptor 1 at each exposure position 3, an electrostatic latent image corresponding to the image is formed on the surface of the photoreceptor 1, and this electrostatic latent image is transferred to a developing device 5.
Developed at

Further, a corona discharger 6 provided opposite to the photoreceptor 1 on the roll 4c electrostatically transfers the developed image (toner image) formed on the photoreceptor 1 onto a paper 7 that is appropriately conveyed. It is something. Paper 7 is sent to a transfer position 9 via a guide 8.

The paper 7 is fed into the synchronous row 210 in advance in synchronization with the transport of the photoreceptor 1, so that the image forming edge of the photoreceptor 1 and the edge of the paper 7 coincide with each other at the pick transfer position 9. . The synchronous roller 10 is driven in synchronization with the movement of the photoreceptor 1 and sends the paper 7 to the transfer position 9.

The paper 7 is stored in a paper feed cassette 11 etc. that is removably provided in the main body of the copying apparatus.

A half-moon-shaped paper feed roller 12 is provided opposite the mounting position of the paper feed cassette 11. Therefore, the sheets 7 housed in the cassette 11 are fed one by one by the rotation of the sheet feed row 212 and sent to the synchronous roller 10. This paper 7 is temporarily stopped at the position of the synchronous roller 10.

The paper 7 reaches the transfer position 9, and the toner image on the photoreceptor 1 is transferred to the paper 7 by the action of the transfer corona discharger 6. After the transfer, the paper 7 is peeled off from the photoreceptor 1. Ru. A conveyor belt 14 is provided between the peeling part of the paper 7 from the photoreceptor 1 and the fixing row 213 which is disposed away from the photoreceptor 1.
is located. The conveyor belt 14 conveys the paper 7 to the fixing roller 13 by bringing the back side of the paper 7 into close contact with the belt through air suction 5'l. This is because the toner image on the paper is in an unfixed state, and in order not to disturb this image, the paper 7 is transported so as to support only the back surface on which no image is formed. The fixing roller 13 is a thermal fixing roller that heats the roller on the side that contacts the toner image to a temperature that allows fixing, for example, and transfers the toner to the paper 7.
heat-fixed to.

The paper 7 that has been fixed by the fixing roller 13 is discharged onto a paper discharge tray 16 via a paper discharge roller 15.

On the other hand, some toner that was not transferred remains on the surface of the photoreceptor l after the transfer. By removing this residual toner from the photoreceptor 1, the photoreceptor 1 is prepared for the next image formation. For this purpose, residual charges are removed from the photoreceptor 1 after transfer by an AC corona discharger 17, and residual toner is removed by a cleaning device 18 provided opposite the roll 4a. After blowing the photoreceptor l beam 17, it is further irradiated with light uniformly by a uniform exposure lamp 19 arranged to make the surface potential uniform throughout.

As a result, the photoreceptor 1 faces the main corona discharger 2 with its surface clean and its surface potential uniform, and is used for the next image formation.

Next, an exposure device for exposing an image onto the photoreceptor 1 of the present invention will be described. The image exposure to the photoreceptor 1 at each exposure position 3-□ and L2° 3-3 is carried out by the lens arrays 20, 21.
．． 22. A copy document 23 for image exposure is placed on a document table 24 made of a transparent glass plate or the like.
The document is placed with the leading edge of the document aligned with the reference edge 25 of the placing table 240.

The original table 14 is reciprocated in synchronization with the movement of the photoreceptor l. The lens arrays 20.degree. 21.22 are fixedly arranged between the document mounting table 24 and the photoreceptor 1 so that the incident end face faces the surface of the document, and each lens array is parallel to each other. Here, lens array 2
0 is a lens array for reduction, lens array 21 is a lens array for equal borrowing, and lens array 22 is a lens array for enlargement.

The original 23 on the original placing table 24 includes a lamp.
``Light is irradiated by the illumination device 26. The light reflected from the original 23 by this light irradiation is projected onto the photoreceptor 1 via any selected lens array 3-1'3-2' 3-3. A triangular reflection mirror 2 that moves in the direction of the arrow in order to guide the reflected light from the original 23 to each lens array.
7 is arranged so as to face the document surface. A fixed reflecting mirror 28 is provided opposite each reflecting surface of this triangular reflecting mirror 27.
．． 29 are provided. The fixed reflection mirror 28 is for guiding the reflected light from the triangular reflection mirror 27 to the lens array 20, and the fixed reflection mirrors to 29 are for guiding the reflected light from the triangular reflection mirror 27 to the lens array 22. When the lens array 20 is selected, the triangular reflecting mirror 27, which is fixed at a fixed position, moves to the position shown in the figure and reaches the image scanning start position 30 of the copy original 23.
Direct the reflected light from the fixed reflection mirror 7-28. Therefore, the image of the copy document 23 is transmitted through the lens array 20.
The image is projected onto the photoreceptor l at the exposure position 3-□. Furthermore, if the lens array 22 is selected, the triangular reflecting mirror 2
7 is moved to the left in the figure to direct the reflected light from the image scanning start position 30 to the fixed reflection mirror 29. As a result, the image of the copy original 23 is projected onto the photoreceptor 1 at the exposure position 3-3 via the lens array 22. Furthermore,
Image exposure by the lens array 21 is performed by the triangular reflecting mirror 2
7 is moved to a position where it does not reflect the reflected light from the image scanning start position 30, and the reflected light is directly transmitted to the lens array 2.
This is done by leading to 1. In this case, the equally borrowed lens array 21 is arranged directly below the image scanning start position 30. Although not shown in the figure, a shutter for switching one optical path is provided for lenses other than the selected lens array so that their optical paths are blocked and images are not projected onto the photoreceptor.

The present invention also provides means for controlling the conveyance timing of the paper 7 by scanning the original in order to match the leading edge of the image formed on the photoreceptor l with the leading edge of the paper 7. It uses the movement of

That is, a magnet 31 is fixed to a part of the document table 24, and a reed switch 32 is provided corresponding to the movement path of the magnet 31. When the reed switch 32 faces the magnet 31 as shown in the figure, its contact point starts the rotation of the ONL and synchronous roller IO. When the reed switch 32 is turned on, the movement of the document table 24 is set so that a distance of Δl is created between the leading edge of the document (reference end 25) on the document table 24 and the scanning start position 30. Therefore, before the image of the original document 23 is formed, the paper 7 waiting on the synchronous roller 10 starts to be conveyed.

In the configuration as described above, each lens array 20.
The image scanning start positions 30 at 21 and 22 are made the same by the optical means of the triangular reflecting mirror 27 and the fixed reflecting mirrors 28 and 29. On the other hand, the lens array 20,
The exposure positions 3 on the photoreceptor 1 at 21 and 22 are different from each other. Therefore, if the synchronous roller 10 is driven in accordance with the movement of the document table 24, the driving timing is always constant, so that the leading edge of the paper 7 coincides with the image forming leading edge of the photoreceptor 1 at the transfer position 9. Not necessarily. In order to match this, a lens array 20 or 2 for variable magnification is used.
The exposure position 3-1 or 3-3 of No. 2 is at a moving speed V of the document mounting table 24 with respect to the exposure position 3-2 of the equally reliable lens array 21. are separated by a distance corresponding to

The above will be described in detail below. Borrowed exposure position 3-
2 to the transfer position 9, the transport distance t1 of the paper 7 from the synchronous roller 10 to the transfer position 9, and when the switch 32 is turned on due to the movement of the document mounting table 24, from the leading edge of the document Distance Δl to image scanning start position 30
shall be. In this case, the paper 7 is transported at a transport speed that matches the transport speed V of the photoreceptor l. Further, the document mounting table 24 has a transport speed of V and V of the photoreceptor 1 at the same magnification. = V. In order to match the image forming edge on the photoreceptor 1 and the edge of the paper 7 at the transfer position 9,
It is sufficient to set it so that Δ1+11=1. Therefore, when the serial lead switch 32 is turned on while the document placement table 24 is being moved, the conveyance of the waiting paper 7 is started by the rotation of the synchronous roller 10.

The time when this paper 7 reaches the transfer position is t7. becomes.

Further, from the time when the synchronous roller 10 is driven, image formation on the photoreceptor 1 starts and the time required for the image forming tip to reach the transfer position is 11/, +4/v.

Therefore, since the relationship is Δl +t1=1, 4+LV=:l-7, and the tips of image formation coincide.

v v On the other hand, when changing the magnification, the moving speed of the document mounting table 24 is controlled according to the magnification changing ratio a. That is, the document mounting table 24 has a moving speed vo """4 with respect to the transport speed V of the photoreceptor 1.
will be moved. For example, if the reduction lens array 20 is selected and reduction copying is to be performed, the document placement table 24
is moved at a faster speed than when it is at the same magnification. Therefore, the time t1 from when the document mounting table 24 moves and the reed switch 32 is turned on until the leading edge of the document (reference edge 25) reaches the scanning start position 30 is as follows. tl=a2L/. The time t for the leading edge of the document to reach the scan start position 30 when the original size is the same is t=7t//, and the time t when the document is reduced is 7t//;
The time to reach 0 becomes earlier by J7/-aIL7.

v v Therefore, the time for the image of the leading edge of the original document 23 to be formed on the photoconductor 1 is accelerated, and if the exposure position is the same as at the same magnification, the time for the image formation start edge of this photoconductor 1 to reach the transfer position 9 is shortened. It's also faster. For this reason, the exposure position 3-1 at the time of reduction is set to be farther from the transfer position 9 than the exposure position 3-2 at the same magnification. That is, in order to match the leading edge of the paper 7 and the image forming start end of the photoreceptor 1, if the distance between the rain exposure positions 3-1 and 3-2 is t2, then 1
2=Δl−aIL. This is because, as explained earlier, when performing reduced copying, the time for the leading edge of the document to reach scanning position 30 is faster by 1 -aIL7 than when performing full-size copying, and this time is 1t/-1t.
v
It is sufficient to make it equal to the time 127 for the seven bodies 1 to advance by t2, and the economic point t2 becomes 4=Δl-aIL.

Therefore, at the time of reduction, the time tz from when the document mounting table 24 turns on the reed switch 32 until the leading edge of the image formed on the photoreceptor 1 reaches the transfer position 9 is aIL;/
+ L2/ + L1/ To;'z Le. The time from when the lead switch 32 is turned on until the leading edge of the paper 7 reaches the transfer position 9 is limited.

t2 is 1. =Δl−aΔl, so the time t
2 is ``y+1+/'' in the economy, which is the same as when the magnification is the same as v v , and the time t when the paper 7 reaches the transfer position 9.

is equal to With this, when reducing the exposure position 3-
0 may be set to be located upstream in the moving direction of the photoreceptor 1 by Δl-aΔl from the exposure position 3-2 at the same magnification.

Next, consider the exposure position 3-3 during enlargement. During enlargement, the moving speed V of the document placement table 24. becomes vo=73 as in the case of reduction.

Here, a is the magnification, and when it is enlarged, 1<a, and the moving speed of the document table 24 is slower than when it is at the same magnification (vo=v). Therefore, the time for the leading edge (reference end 25) of the original 23 on the original placing table 24 to reach the scanning position 30 from the time when the reed switch 32 is turned on is delayed compared to when the original is magnified. The delay time t4 becomes a117-IAyvv. A distance t3 corresponding to this delay time, that is, t3
It is sufficient that the exposure position 3-3 at the time of enlargement is moved closer to the transfer position 9 by one Δl than the exposure position 3-2 at the same magnification.

Therefore, during enlarged copying, the time tsld, a1 from when the original table 24 turns on the reed switch 32 until the leading edge of the image formed on the photoconductor 1 reaches the transfer position 9 is
4'+47-137, 2. Le. Mata, v.
v v Time t from when the reed switch 32 is turned on until the leading edge of the paper 7 reaches the transfer position 9. It is begging. Therefore, since t3 is set to 13=Δl-Bi2, time t5 becomes lL7+47, and at the same time v
Matches between v. Therefore, the leading edge of the paper 7 is at the transfer position 9.
It becomes equal to the time to which it reaches . As a result, the photoreceptor 1
The upper image forming leading edge and the leading edge of the paper 7 match at the transfer position 9 .

As explained above, according to the present invention, when reducing or enlarging, the time the document mounting table 24 takes to travel the distance Δ is faster or slower than when it is at the same magnification, and the distance corresponding to this faster or slower time is Only upper (Δl-aΔl), exposure position 3-
By setting the exposure position 3-1.3-2 apart in 2-2 reduction or enlargement, regardless of whether it is the same size or when changing
The leading edge of the paper 7 and the image formation start end of the photoreceptor 1 can be aligned.

Here, an example will be given below regarding the exposure position for aligning the leading edge of the paper 7 and the image forming leading edge of the photoreceptor l.

The paper transport distance t from the synchronous roller 10 to the transfer position 9 is t = 150 (mm), and the exposure position 3- at the same magnification.
The length tl of the photoconductor 1 from 2 to the transfer position 9 is t+ =
100 Cttan], the distance Δl from the time when the reed switch 32 is turned on to the scanning position 30 is 1=1. From the formula +Δl, Δl = 50 (+m
). Then, the magnification ratio, for example, the magnification is 0.
For 8x (reduction), the exposure position 3-1 of the reduction lens array 20 is expressed by the formula 12=Δl−aΔl, t2=
10 (mm) and 10 [mm] upstream from exposure position 3-2.
■] The settings are shifted. If the magnification is 1.2 times (enlargement), the exposure position 3-3 of the enlargement lens array 22 is t
According to the formula, 3=aΔ is one Δl, t3=10 [■], which can be set by shifting 10 (■) downstream from the exposure position 3-2.

Note that the synchronous row 210 is provided at a distance t from the transfer position 9 for transporting the paper. However, for paper 7, transfer position 9-! It is sufficient to shorten the conveyance time t at the paper 7.
The leading edge can be aligned with the image forming leading edge of the photoreceptor 1 at the transfer position 9 .

In other words, it is sufficient to delay the synchronous roller 10 by the time t6 corresponding to the distance X, which is the shorter paper transport distance t.
When the reed switch 32 is turned on, the ta waiting time setting timer is driven, and the synchronous roller 10 is driven after the timer setting time. As a result, the distance between the synchronous row 210 and the transfer position 9 can be shortened, and the size of the copying apparatus can be reduced.

Effects> According to the copying apparatus of the present invention, in the lens array for equal magnification or variable magnification that performs image exposure, optical means for guiding reflected light from the copy original to each lens array is provided.
The scanning position of the document is always the same, so that the illumination device can irradiate light effectively, and the number of reflective mirrors and the like constituting the optical means can be reduced, resulting in lower costs.

In addition, although the exposure position to the recording medium in each lens array is different, the exposure position during reduction is upstream with respect to the recording medium transport direction, and the exposure position during enlargement is downstream relative to the exposure position when magnifying the recording medium. Since it is set according to the magnification ratio a, the leading edge of the paper and the leading edge of the recording medium on which the image is formed can be easily aligned.

[Brief explanation of the drawing]

The figure is a cross-sectional view showing the configuration of main parts of a copying apparatus according to the present invention. 1: Photoreceptor 2: Corona discharger 3-1: Exposure position for reduction 3-2: Exposure position for equal confidence 3-3: Exposure position for enlargement 5: Developing device 6: Corona discharger for transfer 7: Paper
9: Transfer position 10: Synchronous roller 20: Reduction lens array 21: Equal borrowed lens array 22: Enlargement lens array 27: Movable triangular reflection mirror 28. 29: Fixed reflection mirror 30: Original scanning position 31: Magnet 3
2: Reed switch

Claims (1)

[Claims] 1. By arranging a plurality of lens arrays with different magnifications in parallel and selectively switching the optical path of each lens array, the image of the scanned copy document is transferred to the recording medium at the desired magnification. In a copying apparatus capable of projecting and obtaining a copy, an optical means is provided to switch the optical path of the reflected light from the copy original and selectively guide it to each lens array, so that the image on the recording medium at the same magnification is The exposure position of the equal-magnification lens array is set so that the timing of conveying the transfer material to the position where the image is transferred coincides with the leading edge of the image, and the exposure position of the lens array due to magnification is adjusted to the above-mentioned equal-magnification exposure position. A copying apparatus characterized in that the copying apparatus is set to be located closer to or further away from a transfer position depending on a magnification ratio. 2. The copying apparatus according to claim 1, wherein a timing signal for transporting the transfer material is obtained during scanning of the copy document. 3. Output the transport timing of the transfer material before the start of scanning of the copy original, and when the distance to the start of scanning at this time is Δl, the exposure position when changing the magnification is set to the magnification ratio a from the exposure position when changing the magnification. 3. The copying apparatus according to claim 2, wherein the copying apparatus is shifted by ±(Δl-aΔl).