JPH0151190B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying apparatus that forms a copy image by projecting an original image onto a photoreceptor in a slit shape, and more specifically, the present invention relates to a copying apparatus that projects an original image onto a photoreceptor in a slit shape to form a copied image. The present invention relates to a copying apparatus that forms a copy image using a machine.

2. Description of the Related Art Conventionally, there is a copying apparatus that moves or conveys (hereinafter simply referred to as conveyance) an original document and projects an image of the original onto a photoreceptor in the form of a slit. When the above-mentioned apparatus has two or more different magnification ratios, the method is generally to transport the copying material and the photoreceptor at the same speed at all times, while transporting the original at a speed corresponding to each magnification. has been adopted. A copying apparatus to which the above method is applied operates only the means for changing the projection magnification of the optical system such as a lens and the conveyance speed of the document conveyance means in accordance with the selection of the magnification, and operates other means for driving the photoreceptor. There is an advantage that the mechanism, conditions, etc. for conveying the copy material do not need to be changed. On the other hand, for example,
In a copying device that conveys a sheet-like original by a driving means such as a roller and projects an image of the original onto a drum-shaped photoreceptor to obtain a copied image, the visible image on the photoreceptor is at a transfer position. In order to transfer the image to a predetermined position on the conveyed copy material, the leading edge of the microscope image and the leading edge of the copy material are completely synchronized so that they coincide at the transfer position (hereinafter simply referred to as leading edge alignment). This is required. The time when the leading edge of the image reaches the transfer position is a certain period of time after the image of the leading edge of the document is projected onto the photoreceptor, regardless of the magnification. However, since the document conveyance speed is changed in accordance with the selected magnification, the time point at which the image of the leading edge of the document is projected onto the photoreceptor differs depending on the selected magnification. In order to achieve leading edge alignment in such a case, either detect the document to be transported and change the timing at which the copy material starts to be transported using the above-described delay means corresponding to each magnification, or A conceivable method is to arrange document detecting members of 1, selectively use the document detecting members according to the set magnification, and determine the time to start conveying the copy material based on the signals from these document detecting members.

However, the method described above is undesirable in a copying machine capable of making multiple types of variable-magnification copies, as it requires a large number of delay means and detection members, which leads to the complexity of the machine and the difficulty of adjustment. .

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned inconveniences, and to make it possible to perform edge alignment without complicating the apparatus no matter how many types of variable size copying are performed.

The present invention also includes a document transporting means for transporting the document at a speed corresponding to a selected magnification, and an optical means for projecting an image of the document at the selected magnification onto a photoreceptor that moves at the same speed regardless of the magnification. In a variable magnification copying apparatus having a transfer means for transferring an original image formed on a photoreceptor to a copying material that moves at the same speed as the photoreceptor, an original detection means provided in an original transport path, and an original transport means. a rotating member that rotates at a speed corresponding to the selected magnification in conjunction with the selected magnification, and means for detecting the amount of rotation of the rotating member, and the rotating member is selected from when the original detecting means detects the original. A variable magnification copying apparatus is characterized in that it detects that it has rotated by the same amount of rotation regardless of the magnification applied, sets the tip position at a predetermined position in advance, stands by, and then starts conveying the copy material to a transfer position. It is.

As the document detecting means, a micro switch, a switch using ultrasonic waves, or a switch combining a light source and a light receiving element can be used. Further, in the present invention, the photoreceptor is drum-shaped or web-shaped, and moves together with a copying material such as plain paper at a constant speed regardless of changes in magnification. The (moving) speed of the photoreceptor means the circumferential speed due to rotation when the photoreceptor is drum-shaped, and the moving speed when the photoreceptor is web-like. Further, the document is in the form of a sheet, and the slit portion for projecting the document image onto the photoreceptor is particularly effective for documents that are conveyed while being held between rollers or belts. Further, the present invention can also be applied to a movable document table on which a sheet or three-dimensional document is placed and moved through the slit portion.

Embodiments of the present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows a cross section of a variable magnification copying apparatus which is an embodiment of the present invention.
First exposure unit 1 with a fixed document table for 3D originals
and a second document conveying means exclusively for sheet documents.
It has an exposure section 2. The present invention is applied to the second exposure section of the exposure sections 1 and 2, and variable-magnification copying can be performed only on sheet originals. The photoreceptor is formed into a drum shape, and the photoreceptor drum 4 rotates in the direction of the arrow.
A photoreceptor having a conductive support, a photoconductive layer, and a surface insulating layer is used. Next, the operation of the above device will be briefly explained.

When using the first exposure section 1, place a document on the glass plate 5 for document placement in the exposure section and press the copy start button (not shown), and the photosensitive drum 4 will start rotating in the direction of the arrow. . Next, the lamp 6 for illuminating the original of the optical system and the first movable mirror 7 move in the direction of the arrow at the same speed as the circumferential speed of the drum 4.
Then, in synchronization with the first mirror 7, the second movable mirror 8 moves in the same direction at half the speed of the mirror 7 to scan the original. The original image is transferred to the projection section 1 of the drum 4 via a first mirror, a second mirror 7, 8, a fixed in-lens mirror 9 that includes an aperture and a mirror therein, and a rotatable third mirror 10.
I am guided by 1. The first and second mirrors 7 and 8, which have reached the two-dot chain line position, reverse their moving directions and return to the starting position.

Next, the case where the second exposure section 2 is used will be described. In this case, when the original 13 is placed on the original guide 12 where originals can be stacked and the copy start button (not shown) is pressed, the original 13 is moved to the guide 1
2 is sent out one by one. Then, the sent document 13 passes through a pair of conveyance rollers 16,
Furthermore, the glass plate 18 is moved by the pair of conveying rollers 43 and 44.
The roller 19 passes through a slit portion having a
20 onto the paper discharge tray 21 . Note that when using the second exposure section 2, the third exposure section 2 is used.
The mirror 10 is located at the position indicated by the two-dot chain line, and the reflected image of the original illuminated by the illumination lamp 22 through the glass plate 18 of the slit portion is reflected from the mirror which is movable in order to change the optical path length. The image reaches the projection section 11 of the photoreceptor through a unit 23 and a lens 24 which is also movable in order to change the imaging magnification of the original image.

On the other hand, around the photosensitive drum 4, members and means for forming an image are arranged.
26 is a first corona discharger, 26 is an AC corona discharger which simultaneously performs a static eliminating action and an image projection on the photosensitive drum, and 27 is a lamp for full exposure. An electrostatic image corresponding to the original image is formed on the surface of the photosensitive drum 4 by each of these members 25 to 27. Thereafter, the electrostatic image on the photosensitive drum is developed by a developing device 28 and reaches a transfer section.

In the transfer section, copying material is conveyed in accordance with the visible image on the photosensitive drum, and the copying material that is in close contact with the photosensitive drum 4 in the transfer section receives the electric field of the transfer discharger 29, and the copying material on the drum 4 is transported. The microscopic image is transferred.
The copy material that has been transferred is separated from the drum 4 by the separating means 30. The sheet is discharged onto a paper discharge tray 33 by a conveyance roller 32 via a fixing means 31 .
On the other hand, after the transfer process is completed, the photosensitive drum 4 is uniformly irradiated by the lamp 34, and is further irradiated by the cleaning roller 35 and leaning blade 36.
The remaining developer on the surface is removed before proceeding to the next step.

In the above figure, 37 and 38 are cassettes for storing copy materials, and copy materials 39 of different sizes are stored.
can be stored. Further, reference numerals 40 and 41 are feed-out rollers for sending out the copy material, and the copy material 39 sent out by the roller 41 is synchronized by the register roller 42 and conveyed to the transfer section of the photosensitive drum 4.

Here, when performing variable-magnification copying of a sheet original using the second exposure section 2, the copying magnification ratio is set to 1:1/
If n is the document transport speed when copying at the same size, Vo is
Then, the conveyance speed Vn of the document during variable-magnification copying is
The relationship is Vo:Vn=1:n. Further, the mirror unit 23 and the lens 24 move to the position indicated by the two-dot chain line to form an optical path for variable magnification projection.

Next, the relationship between the projection of the original image from the second exposure section 2, the projected image on the photoreceptor, and the synchronization of conveying the copying material with respect to the image on the photoreceptor will be described. Note that the numbers in FIG. 2 and the following figures are the same as the corresponding members in the apparatus 1 shown in FIG. .

In FIG. 2, the center position of the projection part on the photosensitive drum 4 is designated as point B, the tip position of the copying material 39 loaded in the cassette 37 is designated as point D, and the visible image on the drum 4 is located on the copying material 39. The center position of the transfer position to be transferred is defined as point C. The length along the circumferential direction on the circumferential surface of the drum, the distance between points B and C is L _BC , and the length along the conveyance path between the cassette 37 and the drum 4 is the point C. Let L _DC be the distance between D and copy material leading edge position D. Figure 2 shows L _BC = L _DC
In this case, if the conveyance of the copy material 39 is started at the same time that the leading edge image of the document starts to be projected onto the point B, the circumferential speed of the drum 4 and the conveyance speed of the copy material will be adjusted as described above. Since they are equal, the original image and the leading edge of the copy material can be reliably aligned at the transfer position C. In addition, although the conveyance speed of the document changes with variable-magnification copying, since the drum side always rotates at a constant circumferential speed, it is necessary to start conveying the copy material at the moment when the leading edge image of the document starts to be projected onto the drum 4. The edge alignment can be reliably performed using the same control as when copying at the same size.

FIG. 3 shows a case where L _BC <L _DC in FIG. 2 above. In this case, before the original image starts to be projected at position B, the leading edge of the copy material 34 is conveyed in advance to a predetermined position E point and kept on standby. Examples of methods for transporting the copy material to point E include (a) driving the roller 40 by a timer by the distance L _DE between point D and point E, and (b) driving the roller 40 at point E by a micro switch. The position of the copy material being conveyed may be detected by a detection means such as a sonic element, light and light receiving element, and the roller 40 may be stopped. Here, set L _BC = L _EC . By keeping the leading edge of the copy material on standby with the leading edge aligned with point E as described above, when the leading edge image of the document starts to be projected to the projection position B, as in the configuration shown in FIG. If the conveyance of the copy material 39 is restarted from position E, it is possible to perfectly align the leading edges for full-size and other variable-magnification copies.

FIG. 4 shows a case where the configuration in FIG. 2 is such that L _BC >L _DC . In this case, the copying material 39 is moved along a path corresponding to the difference between L _BC and L _CD for the time required for the copying material 39 to be conveyed at a constant speed from the time when the leading edge of the document starts to be projected onto the point B. Delay the start of transportation using a timer, etc. This makes it possible to align the leading edge of the copy material at the transfer position C point.

As described above, even if the distance between the projection position of the original image and the transfer position and the distance between the feeding position and the transfer position of the copy material are different, the photoconductor side and the copy material side are moved at the same speed and the leading edges are aligned. It becomes possible to do this. Furthermore, by determining the time to start projecting the document onto the photoreceptor, the leading edges can always be perfectly aligned regardless of the magnification or variable magnification. Therefore, below,
The means for determining the projection start time will be explained using an example.

FIG. 5 shows the second exposure section of the apparatus shown in FIG. 1.
In the figure, the width a is the slit width for illuminating the original, and A is the center position of the width a. The sheet-like original is conveyed in the direction of arrow T at a speed corresponding to the selected magnification. In the above configuration, the time when the leading edge of the original passes through point A indicates the time when the leading edge of the original is projected onto point B in FIGS. 2 to 4. That is, it is sufficient to detect the point in time when the leading edge of the document passes through point A, and use the detected signal to command the conveyance of the copying material whose leading edge is pre-arranged at the same position for any magnification.

By the way, as a method for detecting copy material passing through point A, a micro switch is provided at the point A,
Possible methods include detecting the presence of a document based on its thickness when the document passes, or by providing a light source and a light receiving element at point A so that the document blocks the light from the light source when the document passes. However, since point A is the exposure position of the document, if these position detection means are provided in the slit portion, these detection means will be projected onto the photoreceptor along with the document image. The present invention also improves the above points. In the present invention, the time required for the following rotating member to rotate by a predetermined amount is added to the time when the leading edge of the document passes the document detecting means, thereby determining the point in time when the document starts to be projected onto the photoreceptor. . In FIG. 5, there is provided one document leading edge detection member I provided along the document conveyance path, and a rotating member that rotates in motion at the document conveyance means at the same speed as the document conveyance means. In the figure, reference numerals 43 and 44 denote a pair of document conveyance rollers constituting a part of document conveyance means, and 45 denotes a pulse generating plate, which is fixed to the conveyance roller 43 while avoiding the document conveyance path. moves with the same rotational angular velocity as. The rollers 43 and 44 rotate at a speed corresponding to the selected magnification in order to convey the document at a speed corresponding to the selected magnification, and therefore the pulse generating plate 45 also rotates at a speed corresponding to the selected magnification. do. _N1 holes are provided at equal intervals on the outer periphery of the pulse generating plate 45, and a fixed portion 46 extending across the holes is a pulse signal detecting member. Here, the document transport direction T
Assuming that the distance between the above-mentioned detecting section I set upstream of the slit section and the center A of the slit section is d, after the leading edge of the document reaches the detecting section I, the document is transported by a distance d. roller 43
is, regardless of its rotational speed, its outer circumference is a distance d
It is sufficient to rotate by an amount corresponding to , that is, an angle α (as shown). The angle at which the pulse generation plate 45 rotates at this time is also α, and the pulse detection member 4
The number of pulses detected by the sensor 6 is also N ₂ =N ₁ ×α/2π, so the relationship is always constant regardless of the document conveyance speed. Therefore, after counting _N2 pulses from the time when the leading edge of the original passes the detection section I (the time required for counting is inversely proportional to the original conveyance speed), the leading edge of the original is located at the center A of the slit. Therefore, at that time (Figs. 2 and 3) or after a certain period of time at any magnification from that time (Fig. 4), the copying material whose tip has been set in advance at a predetermined position D or E and kept on standby is directed to the next process. , by starting the conveyance, it becomes possible to align the leading edge of the image for any variable magnification copying. Note that in FIG. 5 above, the pulse generating plate 45 is provided coaxially with the roller 43;
It does not necessarily have to be coaxial with the document transport roller 43 as long as it is synchronized with the document transport means. Also, instead of the pulse generation plate 45 and the pulse detection member 46,
Of course, a combination of a rotary cam member provided via a clutch and a micro switch may also be used.

Also, when aligning the tips with higher precision,
The register roller 4 described in FIGS. 1 to 4 above
2 can be used. That is, the registration roller 42, which is closer to the transfer section, is temporarily stopped rotating just before the copy material 39 arrives to prevent the copy material 39 from advancing, thereby causing the copy material to sag. Thereafter, when the roller 42 is rotated again, the unstable conveyance movement of the copy material that occurred during conveyance is absorbed, and good leading edge alignment is achieved. The signal for controlling the roller 42 may be obtained separately from the copy material conveyance start signal based on the signal when the leading edge image of the document is exposed to the photoreceptor, and the signal may be delayed by a delay means such as a timer. good. Further, in this case as well, since the same delay means can control various types of variable size copying, the apparatus and control method are extremely simple.

In any case, according to the present invention, there is no need to provide document detection means, delay circuits, etc. in the number corresponding to the selectable magnifications, and even in a multi-step variable magnification device, the difference between the document image and the copy material can be adjusted with a simple configuration. Tip alignment can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a copying apparatus to which the present invention is applied;
2 to 4 are cross-sectional views of the conveying section showing a copying material standby state, and FIG. 5 is a cross-sectional view of the slit section to which the present invention is applied. In the figure, 2... second exposure section, 4... photosensitive drum, 13...
...Original, 16-20...Transport roller, 18...Glass plate, 22...Lamp, 24...Lens, 39
... Copy material, 43, 44 ... Original transport roller, 4
5...Pulse generation plate, 46...Pulse detection member,
I...Detection means position.

Claims (1)

[Scope of Claims] 1. A document conveying means for conveying the document at a speed corresponding to a selected magnification, and an optical system for projecting an image of the document at the selected magnification onto a photoreceptor that moves at the same speed regardless of the magnification. In a variable magnification copying apparatus, the variable magnification copying apparatus has a means for detecting an original document, and a transfer means for transferring an original image formed on the photoreceptor to a copying material that moves at the same speed as the photoreceptor. A rotating member that rotates at a speed corresponding to a selected magnification in conjunction with a conveying means, and means for detecting the amount of rotation of this rotating member, and the rotating member rotates when the original detecting means detects the original. A variable magnification device that detects that the has been rotated by the same amount of rotation regardless of the selected magnification, and starts transporting the copying material that has been kept waiting with the tip position set in advance at a predetermined position to the transfer position. Copying equipment.