JPS6259943A - Image forming device - Google Patents

Abstract

PURPOSE:To improve oeprativity by providing a means which moves a lens by specific distance from on a straight light connecting the mid-point of the maximum width of original mounting and the mid-point of maximum image width together toward an original reference end. CONSTITUTION:An original is placed on original platen glass 1 on the basis of one end in a direction perpendicular to its scanning direction and transfer paper 17 is arranged on the basis of the center in a direction perpendicular to its feeding direction. A photosensitive body 11 is exposed to the image of the original 2 through the zoom lens 10 which is movable in two directions to form an image on the transfer paper 17. When this formed image is larger than the width of the transfer paper 17, the zoom lens 10 is moved from on the straight line connecting the mid-point of the maximum original mounting width and the mid-point of maximum image width together toward the original reference end by the distance lX shown by an equation, where L0 is the maximum original width, lC is the transfer paper width, and (m) is image formation magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to image forming apparatuses such as copying machines and printers.

(Prior Art) Conventionally, as the above-mentioned copying bag 21, etc., there are the following types in terms of the positional relationship between the original and the transfer paper on which the image thereof is formed. That is, the original is placed on the original 4 & 21 stand with one end in the direction orthogonal to the scanning direction as a reference (hereinafter referred to as one side original reference), and the transfer paper is placed on one end in the direction orthogonal to the feeding direction as the reference. (hereinafter referred to as transfer paper one side 7! quasi), and the original is placed on the original placing table with the center in the direction orthogonal to the scanning direction as a reference (hereinafter referred to as the original center reference). 2. Description of the Related Art There is an apparatus in which transfer paper is arranged with the center of the transfer paper in a direction orthogonal to the feeding direction as a reference (hereinafter referred to as a transfer paper center reference). Then, place 21 of the manuscript and transfer paper.
Optical devices, transport pieces 21, and the like are arranged depending on the relationship.

However, such conventional technology has the following problems. In image forming apparatuses that use a one-sided transfer paper reference, due to the recent diversification of transfer paper materials and sizes, because of the one-sided reference, there are problems with paper feeding errors and skew due to the positional relationship of the paper feed roller. Furthermore, inconveniences such as line feeding are likely to occur.

As a device for separating and transporting transfer paper from the photoreceptor,
When using separation belts or pressure rollers that separate and transport one side of the transfer paper, the load resistance that the transfer paper receives in the direction perpendicular to the direction of movement becomes uneven, resulting in poor separation, poor transport, or the resulting transfer. Problems such as image defects on paper, such as transfer misalignment and image surface distortion, are likely to occur.

Also, if the transfer paper is based on one side, the fixing device also
Paper wrinkles, etc., caused by the above-mentioned separation and poor conveyance occur, and in addition, fixing defects occur due to uneven fixing temperature when passing small size paper, which inevitably reduces the function of the image forming apparatus.Furthermore, transfer When paper is based on one side of the paper, the current f! The developer is consumed only on one side of the device, resulting in non-uniform image density, which causes image density unevenness on large-sized paper that is subsequently developed, which also reduces the performance of the image forming device.

−・force, (center of the document) In image forming equipment that employs the standard, the center in the direction perpendicular to the scanning direction), '
Because the original is placed on the original placing table as a standard, it is not possible to set a clear original placement standard as in the case of the original one side standard, which uses one end of the original as the standard. 1.
However, there arises a problem that the operability during the transfer process is very poor, and furthermore, the accuracy of the image on the transfer paper is very low.

Furthermore, in the case of document center reference, there is no guarantee of reliable document position even in multicolor copying, which has been increasingly used in recent years, i.e., when colors are superimposed on transfer paper, image misalignment is likely to occur. There is a problem that it cannot be used.

Therefore, in order to solve the above-mentioned problem, the applicant has developed a lens that projects the image of the original onto the photoreceptor, which can be moved in two directions, so that when the original is placed on one side, the lens is movable in two directions. We have proposed a device that improves the operability and positional accuracy of the transfer paper, and uses a transfer paper center reference to prevent paper feeding failures, skewed single paper wrinkles, etc.

FIG. 3 shows this proposed device, in which one end of the original 2 in the direction orthogonal to the scanning direction (direction perpendicular to the paper surface) is placed on the original protrusion provided at one end of the original placing glass 1. The manuscript is against the board 50! 21 Place it on glass 1. Therefore, the image of the rX draft 2 is transferred to the photoreceptor 1.
The lens 10 to be projected onto the image plane is crossed by a predetermined amount y, fLx in the optical axis direction (X direction) and in the direction perpendicular to the optical axis direction (X direction).
The image of the document 2 is exposed to light at the center of the photoreceptor 11 in the axial direction, and is visualized. The transfer paper 17 to which this FIj image is transferred is placed at the center in the direction orthogonal to the feeding direction (direction perpendicular to the paper surface) corresponding to the &l11 image on the photoreceptor 11, and is transported.

(Problems to be Solved by the Invention) However, in the case of such conventional technology, the image of the original 2 is enlarged, and the image of the original 2 is enlarged. Transfer part of the Ij image to transfer paper 17
When attempting to copy the image, the image is always projected onto the center of the photoreceptor 11 by moving the lens 10 in the X direction, and is visualized. Therefore, when a part of this visible image is transferred to a smaller transfer paper 17, the P of the original 2! A draft abutment plate 50
As shown in FIG. 15, the images on the side and the opposite side overflow from both ends of the transfer paper 17 and are not copied. Therefore, the edge of the document 2 on the document abutting plate 50 side is not copied onto the edge of the transfer paper 17. Since the copies are not made in unison, the operator cannot know which part of the original 2 is to be copied, and there is a problem in that it is difficult to obtain a desired copy.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art.The purpose of the present invention is to adopt the document side reference and the transfer paper center reference to convert the document to 'a';
Y! This is a variable magnification image forming apparatus that improves operability and positional accuracy when transferring paper, and prevents the occurrence of paper feeding errors, skewed single paper wrinkles, etc. Another object of the present invention is to provide an arrangement for an image forming apparatus so that an image at a reference edge of a document coincides with one edge of a transfer sheet.

(Means for Solving the Problems) In order to achieve the above object, the present invention supports a document on a document support member with one end in a direction orthogonal to the scanning direction as a reference, and also supports a transfer material in a 70-day feed. In a device that is arranged with the center in a direction orthogonal to the feeding direction as a reference, and that forms an image on a transfer material by exposing an image of a 1iiJ document onto a photoreceptor through a lens that can move in two directions. If the image to be created is larger than the width of the transfer material, if the width of the large document is set to Lo, the width of the transfer paper is set to ic, and the image formation magnification is set to m, the lens is moved to the distance given by ! The image forming apparatus is configured to include means for moving the largest original @ from the straight line connecting the midpoint of the width and the midpoint of the maximum image width to the original reference edge side.

(Example) Hereinafter, the case for Book 5-2 will be explained based on the illustrated embodiment.

FIG. 1 is a sectional view showing a copying device capable of double-sided and multiple copying using bright colors as an embodiment of an image forming apparatus according to the present invention. Manuscript i! c22 glass l ni 4171
The original 2 is illuminated by a lamp 3, and its light image is reflected by reflection mirrors 4, 5, 6, 7, 8°9 and a zoom lens l.
The light is guided to the photosensitive drum 11-31 by an optical system composed of O. The lamp 3, the mirror 4, and the mirror 5.6 each move at a predetermined speed in the direction of the arrow to scan the original 2. On the other hand, since the photosensitive drum 11 is also rotated in the direction of the arrow after its surface is uniformly charged by the primary charger 12, electrostatic latent images corresponding to the original image are sequentially formed on the surface of the photosensitive drum 11. Ru. A color developer 13 containing color toner (for example, red, blue, etc.) and a black developer 14 containing black toner are arranged around the photosensitive drum 11. These developing devices 13 and 14 are movable in the directions of the arrows, and approach the photosensitive drum 11 to visualize the electrostatic latent image on the photosensitive drum 11 according to a desired color image. In the case of this figure, since the color developing device 13 is far away and the black developing device 14 is close, a black image is formed on the photosensitive drum 11. This image is transferred to a transfer paper 17 as a transfer material by a transfer charger 15.
transcribed to. After that, the photosensitive drum 11 is cleaned by a cleaner 16.
At this point, residual toner on the drum surface is removed, and the next copying process is started again.

The transfer paper 17 is fed as follows, and the original image is copied.

There are three methods for feeding the transfer paper 17 into the copying apparatus. In the first method, sheets are stacked in a cassette on one day and fed to a pair of rollers 20 by a feed roller 19. When a plurality of sheets of transfer paper 17 are fed into the roller pair 20,
Only the top paper is separated and fed into the apparatus, and after passing through this pair of rollers 20, the transfer paper 17 is transferred to the guide F.
Registration rollers 23 are reached via plates 21 and 22. Second
In this method, the sheets are loaded in a cassette 24 and sent to a pair of rollers 26 by a feed roller 25.

The roller pair 26 has the same moat as the previous roller pair 20, and after the transfer paper 17 passes through the roller pair 26, it passes through the guide plate 27.
It reaches the registration roller 23 via 28. The third method is so-called manual paper feeding, and in this case,
When the manual feed tray 29 is rotated in the direction of the arrow, the manual feed middle plate 30 follows this movement and slips under the paper feed roller 25. At this time, the transfer paper 17 in the tray 24 interferes with the manual feed middle plate 30. It is pushed down to prevent it from happening. In this state, it is placed on the manual feed intermediate plate 30 and the manual feed tray 29, and the registration rollers 23 are placed in the same manner as in the second method.
sent to. The registration roller 23 is the photosensitive drum 11
The rotation is started at a timing so that the transfer paper 17 matches the visible image of the upper transfer guide 31. Lower transfer guide 32
The transfer paper is fed onto the surface of the photosensitive drum 11 through the transfer charger 15, and the image on the surface of the photosensitive drum 11 is transferred to the transfer paper by the transfer charger 15. The transfer paper is separated from the drum surface by the separation charger 33 and transferred to the conveyance section. Heating roller 35 via 34
a and a pressure roller 35b. The image on the transfer paper is fixed as a permanent image by heating and pressure in the fixing device 35, and the transfer paper 17 is heated and pressurized by the first discharge roller 3.
6 and then to the flapper 37. The paper reaches the second ejection roller 39 via the flapper 38 and is then ejected from the copying machine.In Figure 0, the flapper 38 is shown blocking the transfer paper path, but this flapper 38 is used to remove light material It is made of 100% aluminum and is rotatable in the direction of the arrow, so when the transfer paper passes, it is pushed up by the leading edge of the transfer paper and takes a position t when it is retracted from the transfer paper, so there is no need for the transfer paper to pass. No problems will occur.

Furthermore, this copy? When setting , double-sided and multiple copies are rotated.

When the duplex copying operation is instructed to the copying device, the original image is transferred and fixed on one side of the transfer sheet in the same way as the basic operation described above, and the sheet is sent to the second ejection roller 39 and ejected onto the tray (T). The rear edge of the transfer paper is detected by the detection lever 40.
and an optical sensor 41, and then for a certain period of time (i.e., when the trailing edge of the transfer paper reaches the flapper 3).
8), the second ejection roller 39 starts to reverse rotation and feeds the transfer paper into the transfer device again, and the transfer paper 17 is then passed through the flapper 38 and the flapper with the rear end first. 37 left slope and guide plate 4
2 and further via the guide plates 43, 44 to the roller 4.
Sent to 5. Thereafter, the transfer paper 17 passes through the rollers 46 and reaches the horizontal registration rollers 47. At this point, the horizontal registration roller 47 has stopped, and the transfer paper is
After the roller pair 45 and 46 are completely pierced, the roller pair 45 and 46 also stop. Then, the transfer paper waits for copying operation to the other side. When a copy signal for the other side is issued, the horizontal registration roller 47 starts rotating and feeds the transfer paper to the registration roller 23 via the guide plates 48 and 49.
3, the side edge of the transfer paper is detected by an optical sensor (not shown), and the horizontal registration rollers 47 are moved perpendicular to the paper traveling direction so that the side edge is at the same position as when it was first opened. , that is, in a direction perpendicular to the drawing, to correct the lateral alignment t of the transfer paper. Transfer paper is on registration roller 23
The operation after reaching is the same as the basic operation described above, and the transfer paper with the image copied on the other side is finally discharged onto the tray (T) outside the apparatus by the second discharge roller 39. be done.

On the other hand, in the first copying operation when the copying apparatus is instructed to perform a multiple copying operation, the original image is transferred and fixed onto the transfer paper as in the basic operation. In the case of multiple copying, the fuller 2 bar 37 is located in the state shown by the broken line. Accordingly, the transfer paper 17 is sent out by the first discharge roller 36 with the front end first, sent along the right slope of the flapper 37 to the guides 42 and 43, and further sent to the roller 45 via the guides 43 and 44.

Thereafter, the transfer paper 17 passes through the rollers 46 and reaches the horizontal registration rollers 47. The rear end of the transfer paper 17 is the detection lever 40. After being detected by the optical sensor 41 and a predetermined period of time has elapsed, the fuller/pa 37 returns to the solid line position. Then, when the second copy signal is issued, the horizontal registration roller 47 starts rotating, but the movement of the transfer paper at this time is the same as in the case of double-sided copying.

Transfer paper 1 has been subjected to a second image copy on the same side.
7 is finally discharged onto the tray (T) by the second discharge roller 39. Note that although this explanation has been made regarding multiple copying performed twice, the movement of the transfer paper is basically the same even in the case of multiple copying performed more frequently. The only difference is that the flapper 37 returns from the position t shown by the broken line to the position shown by the solid line before the final copying.

Further, in this embodiment, an apparatus that performs duplex or multi-copy copying is described one by one, but this apparatus may be provided with a so-called intermediate tray so as to be able to make double-sided or multi-copy copies of a plurality of sheets in advance.

By the way, in the ffi IJ+ copying apparatus, one end of the document in the direction perpendicular to the scanning direction is 7. Ti
As a standard, the original document a is rubbed on one table, and the transfer material is placed with the center in the direction orthogonal to the feeding direction as a reference.

That is, as shown in FIG. 2, a document abutting plate 50 is provided on the document platen glass 1 at one end in a direction perpendicular to the scanning direction (direction perpendicular to the drawing). 2 is the original ma2 with its one end abutted against the document abutting plate 50.
1 glass l. On the other hand, transfer paper 17
is arranged so that its center always coincides with the center in the direction perpendicular to the feeding direction. More specifically, since the transfer paper 17 is moved in the feeding direction by the registration rollers 23 and the image of the Jtc original 2 is directly transferred from the photosensitive drum 11, the position of the transfer paper 17 in the direction perpendicular to the feeding direction is It coincides with drum 11. Incidentally, in FIG. 2, the photosensitive drum 11 is shown in a flat shape for convenience. Incidentally, the image of the document 2 is projected onto the photosensitive drum 11 via the reflecting mirrors 4.5, 6, 7, 8.9 and the zoom lens 10, but the photosensitive drum 11 is normally projected in the above-mentioned feeding direction. The position and size in the direction orthogonal to the original 2 match the maximum size of the original 2 in the same direction. Therefore, when using manuscript 2 as a reference, rX
The center 0 of the maximum size L in the direction perpendicular to the document scanning direction
1 coincides with the center 02 of the photosensitive drum 11 and the center 03 of the transfer paper 17.

In order to satisfy this relationship, the original 1a 21, the glass 1, the photosensitive drum 11, and the transfer paper 17 housed in the cassettes 1B and 24 are arranged.

By the way, as shown in FIG. 3, the image of the original 2 is projected onto the photosensitive drum 11 by the zoom lens 10, and the relationship among the original 2, the zoom lens lO, and the photosensitive drum 11 is as shown below. There is. Note that the reflecting mirrors 4, 5,
6, 7, and 8.9 only change the direction of the projection optical path during the day, but do not change the optical path length.

First, the original 2 when copying at the same size. To explain the positional relationship between the lens 10 and the photosensitive drum 11, the document placement glass 1
．． The distance fllL between the original 2 placed at position h and the photosensitive drum 11 (for convenience, the transfer paper 17 is placed at the exposure position l of the photosensitive drum 11 in the diagram) is determined by the focal length of the zoom lens 10. is determined, and the lens lO
It is arranged at the optical center of 7. Furthermore, lens 1o
is the maximum width LO of manuscript 2, which is determined by the manuscript text size 50.
is arranged so as to be projected onto the transfer paper 17 having the same radius Lc. here.

When copying a document 2 having an alignment 0 narrower than the maximum document width LO, the image is transferred between the transfer paper 17 having the maximum width Lc and the center 03.
The lens 10 is moved by a distance x in the direction of the arrow so that the lens 10 is formed on the transfer paper 17 of the radiation fLc disposed so that they match. Here, the displacement of the lens LO is given by 41JFltX=(Lo-no)/4. By doing this, even if the original 2 is placed on one side of the original (a) on the original placing glass 1 and the transfer paper 17 is placed with the center as the reference, it is possible to always perform proper copying. can.

Next, the document 2 during variable size copying. The positional relationship between the zoom lens 10 and the photosensitive drum ll will be explained with reference to FIG. Here, when copying an original 2 with zero convergence at a magnification m, the optical center position of the lens 10, that is, the maximum original size 211111gLo and the maximum image width Lc, ! ? The optical axis from the intersection C when the ends are tied diagonally, that is, the largest original! 21 The direction along the straight line connecting the midpoint of LO and the maximum image width Lc (X direction) and the direction from the optical axis to the document reference edge side Let's talk about the amount of movement.

First, for the movement μ in the optical axis direction, when using the zoom lens 10 with a constant optical path length, the physical world ratio is equal to the magnification m, so the following holds true, and this equation is transformed.

It can be expressed by

, On the other hand, the amount of movement in the direction perpendicular to the optical axis is determined as follows.

Movement of the zoom lens IO in a direction perpendicular to the optical axis: 11 indicates that the image projected by the zoom lens 10, that is, the intersection 0 of the image to be formed is the intersection C of the width of the transfer paper 17.
(Here, the convergence of the transfer paper refers to the dimension in the direction perpendicular to the feeding direction). It's different.

First, regarding the case of 1 sentence 0 ≦ sentence C, we will use Figure 4 to explain theory I.
Do I+.

The center of the maximum document width LO is P, the center of document text 0 is Q, &1
Let the center of the surface be R, and the lens position t when the zoom lens 1° moves to the predetermined imaging position is Q', and this is 2? The intersection of Ill and 1αmPR directly from Q' to mPR is P'
Then, P'Q'=(cross x)=PQ--1+m.

Next, the case of 1m1o>ie will be explained using FIG. 5.

When the convergence C of the formed image is larger than the convergence C of the transfer paper 17, as shown in FIG.

The image of the FXT 142 is projected by the zoom lens 10 so that the reference edge of the image of the YX document 2 coincides with one end of the transfer paper 17. In this case, the lens position when the zoom lens 10 moves to the predetermined imaging position t is Q', one end of the imaging position when the zoom lens 10 moves to Q' is U, and the zoom lens lO is at Q''. One end of the imaging position when moving is v,
Base of rX draft 2? I1. If the end is W, then m 0 - intersection C UV = □, and from the similar relationship between ΔWQ'Q'' and ΔWUV, ci,
'-m~=Given by phantom Bigoyu・-21+m.

Therefore, in a copying machine that uses the transfer paper as the central reference while the original is on one side, the amount of text in the optical axis direction is given by the function of the magnification m! In addition, in the direction perpendicular to the optical axis, it is necessary to move the zoom lens 10 by M l x given by a function of the magnification m and the original convergence θ or the transfer paper width 1c. In particular, when enlarging an original and copying a part of it, or when copying a part of a large original onto small-sized transfer paper, the convergence m of the formed image 0 may be the convergence of the transfer paper 17. If it is larger than C, move the zoom lens 10 in the direction perpendicular to the optical axis according to formula (II[), so that one end V of the image to be transferred to the transfer paper 17 is aligned with the reference end W of the original 2. can be done.

FIG. 6 shows a mechanism for moving the zoom lens 10, which includes a first moving means 52 for moving the lens lO in the optical axis direction, and a first moving means 52 for moving the lens 10 and the first moving means 52 along the optical axis. and a second moving means 53 for moving in the perpendicular direction. The upper second first moving means 52 has a lens stand 54, and a feed screw 59 is rotatably mounted on support plates 55 and 56 erected on the A&lens stand 54 via bearings 57 and 58. Supported. This feed screw 5
A feed screw gear 60 is integrally fixed to one end of the lens holder 9, and the feed screw gear 60 is connected to a drive gear 62 attached to a pulse motor 61 that is fixed to the lens stand 54 and can freely rotate forward and backward.
It's in sync with. The zoom lens 10 is fixed to a lens holder 63, and a slot 64 is fixed to one side of the lens holder 63. This nut 64 is screwed into a feed screw 59, and by rotating the feed screw 59 by the wA movement of the pulse motor 61, the trolley 4 is moved in the y direction. That is, by rotation of the pulse motor 61, the zoom lens lO is movable 1E in the y direction (optical axis direction).

Further, a cam groove plate 65 is fixed on the lens stand 54 at an angle with the optical axis direction, and a cam plate 67 is engaged with the cam groove plate 65 via a pin 66. . This cam plate 67 slides i' onto the lens holder 63 in the X direction.
It is maintained in IT function.

This is a well-known member for changing the focal length of the zoom lens 10 in order to keep the optical path length constant and satisfy the imaging conditions as the zoom lens 10 moves.

The lens stand 54 is movable by a second moving means 53 in a direction perpendicular to the optical axis. That is, the lens stand 54 is slidably supported via bearings 72 on guide rails 70.degree. In addition, the front side plate 68
A feed screw 73 is rotatably installed between the rear side plate 69 and the rear side plate 69 via a bearing 73a, and is connected by a feed screw gear 74, a drive gear 75, a pulse motor 76, and a nut 77 fixed to the lens stand 54 in the same manner as described above. This configuration allows the lens stand 54 to move in the X direction. That is,
The zoom lens 10 is movable together with the lens stand 54 in a direction perpendicular to the optical axis by rotation of a pulse motor 76.

FIG. 7 shows the document size detection means. That is,
A plurality of openings are provided in the document pressing plate 78 in a direction perpendicular to the document scanning direction, and optical sensor units 79, 80 and 81, 82 each comprising a light emitting element and a light receiving element are embedded in the openings. When the document pressure bonding plate 78 is closed, these optical sensor units 79, 80, 81, 82 receive the amount of light emitted from the light emitting element reflected from the document surface by the light receiving element, and each light Sensor Uni 1) 79,
The presence or absence of the original document 2 in the second area 79', 80', 81', and 82 corresponding to the original document A glass 1'' corresponding to 80, 81, and 82 is detected, and as a result, the size of the original document A2 is detected. .

FIG. 7 above also shows means for detecting the size of the transfer paper. On the back of the cassette 24 that accommodates the transfer paper 17, there is a size (
Protrusions 83 and 84 corresponding to the horizontal size) are provided. In addition, when this cassette 24 is attached to the main body, the protrusions 83 and 84 on the back of the cassette 24 are J:0N10.
Switches 85, 86 and 87, 88 which are turned OFF are provided. The above switch 85', 86°87.8
The horizontal size of the transfer paper 17 housed in the cassette 24 is detected by 0N10FF of 8. These switches 85
．． The sizes of 0N10FF of 86, 87.88 and the transfer paper 17 correspond to each other.

On the other hand, in the manual paper feed system using one manual feed tray 29, as shown in FIG. An optical sensor unit is embedded, and this optical sensor unit detects the transfer paper 17.
Detects the horizontal size of. That is, when the transfer paper 17 is placed in the manual feed slot 89, the horizontal size of the transfer paper is detected based on whether the light receiving elements 93, 94, 95 detect the light emitted from the first light emitting element 90, 91, 92. It is. If it is detected how many photosensors are in the ON state, the horizontal size of the transfer paper can be recognized using a preset program. Note that the optical sensor of this example
The reason why UNI/) is only on one side of the manual feed port 89 is because it is based on the center of the transfer paper.

In addition, the original size, magnification, and transfer paper size are
It is also possible to input the keys manually from the operation panel, and as shown in FIG.
A transfer paper size designation key 98 and a number 4 key 99 are provided. To enter the original size, press the yX original size designation key 96 and enter the original size using the numerical keys 99. The same applies when entering the 1 magnification and transfer paper size. This is a microswitch that detects whether the plate 78 is opened or closed.

FIG. 8 is a block diagram showing the W system.
102 and 103 are CPUs that control the copying operation, and 102 and 103 are pulse motors 61 and 103 that control the copying operation, respectively.
A driver for driving 76, 96, 97, and 98 are the original size, magnification, and transfer paper size designation keys, 99, respectively.
1 is the number 1 key, 79 to 82 are the document size detection sensors, 100 is the micro switch, 85 to 88
is the sensor for detecting the size of the transfer paper.

Note that for the sake of convenience, the transfer paper size detection sensors 90 to 9 are
5 is not shown.

In the above configuration, the copying head according to this embodiment performs copying as follows. That is, with one end of the original 2 resting against the P'X original plate 50, place the original 2 on the original glass l, close the 'a original pressure signboard 78, and this will trigger the microswitch. 100, and the CPU 10I inputs the three values of original size, transfer paper size, and magnification as follows. That is, the document size designation key 96 on the operation panel. Enter original size 1G, transfer paper size lc, and magnification m from the transfer paper size specification key 98, magnification specification key 97, and numeric key 99, respectively, or use jX original size to and transfer paper size lc for original size detection. The information is input via sensors 79 to 82 and transfer paper size detection sensors 85 to 88 or 90 to 95. CPU101 has these original size 10
゜The size of the image to be formed m l based on the transfer paper size lc and the magnification m
The movement of the zoom lens 10 is expressed by the formula:

Calculate the intersection y, and if 1m 0>TachiC, use formula (I) and (I
II) The amount of movement lx of the zoom lens lO is determined by the formula.

Calculate the intersection y. Next, the CPU 101 sends a signal to the drivers 102 and 103 based on this calculation result, and drives the pulse motors 61 and 76 to move the zoom lens 10 from the optical center position 211c to a position where the coordinates intersect X and y. As the object moves, the focal length changes. Thereafter, when a copy button (not shown) is pressed, the image of the original 2 is copied onto the transfer paper 17 at a predetermined size *m through the image forming process as described above. Note that the magnification in the scanning direction is controlled by changing the moving speed of the optical system and the rotational speed of the photosensitive drum, as is known.

Therefore, if the size of the image to be formed on the transfer paper 17 is smaller than the transfer paper size lc, the image will be formed on the transfer paper 17 in the direction perpendicular to the feeding direction of the transfer paper 17, as shown in FIG. Margins are formed evenly on both ends (of course, no margins are formed in the case of mJljow intersection C), and the size of the image to be formed is m f
If l g is larger than the transfer paper size Jlc, the first
As shown in FIG. 0, the image at the reference edge of the original 2 is copied so as to coincide with one edge of the transfer paper 17.

Figures 11 to 13 show the above operations, document size detection,
3 is a flowchart showing operations for detecting transfer paper size.

In the illustrated embodiment, a zoom lens with a variable focal length is used as the lens, but instead of a zoom lens, a so-called fixed focal length lens may be used to vary the l and optical path length accordingly. Of course, it is possible.

In addition, in the illustrated embodiment, the first. Second moving means 52.
53 has explained the case where the zoom lens 10 is moved in the optical axis direction and in the direction perpendicular to the optical axis, but the case is not limited to this, and the moving directions of the first moving means and the second moving means are different. They do not need to be perpendicular to each other or coincide with the optical axis direction.

Furthermore, in the above embodiment, when m 0≦C, (II
) The case where the zoom lens 10 is moved based on the equation (III) has been described, but the zoom lens 10 is moved based on the equation (III).
You may try to move O. In such a case,
An image is formed on the transfer paper 17 as shown in FIG.

(Effect of Issue 11) The present invention consists of the above configuration and operation.

In a device that uses one side of the original reference and the center reference of the transfer paper, and is capable of variable magnification, if the size of the image to be formed is larger than the size of the transfer paper, the lens movement jIt is changed from normal. Therefore, even if the formed image overflows the transfer paper, the image at the reference edge of the original always matches one edge of the transfer paper, and the operator can accurately grasp the area of the image to be formed on the transfer material. This can significantly improve operability.

4. Il'J Tun Theory of the Drawings Figure 1 is a sectional view showing a copying device as an embodiment of the image forming apparatus according to the present invention, and Figure 2 shows the positional relationship between the original, lens, and transfer paper. The explanatory perspective views, FIGS. 3, 4, and 5 are illustrations showing the positional relationship of the original, lens, and transfer paper, respectively.
η sectional view, FIG. 6 is a construction drawing showing the lens moving means, FIG. 7 is a perspective view showing the rX document and transfer paper size detection means, FIG. 8 is a block diagram showing the control system, and FIG. 1st theta
11 is a flowchart showing the copying operation, FIG. 12 is a flowchart showing the rX document size detection operation, and FIG. 13 is a flowchart showing the transfer paper size detection operation.

FIG. 14 is a plan view showing another embodiment of the image position on the transfer paper, and FIG. 15 is a plan view showing the image position on the transfer paper F in a conventional copying machine.

Explanation of symbols 1...Original glass 2...Original 10...Zoom lens 11...Photosensitive drum 17...Transfer paper 52...First moving means 53...No. 2 means of transportation

Claims (1)

[Claims] A document is supported on a document support member with one end in a direction orthogonal to the scanning direction as a reference, and a transfer material is arranged with a center in a direction orthogonal to the feeding direction as a reference, In a device that forms an image on a transfer material by exposing the image onto a photoreceptor through a lens movable in two directions, if the formed image is larger than the width of the transfer material,
Maximum original width is Lo, transfer paper width is lc, image formation magnification is m
Then, the lens is connected by a straight line connecting the midpoint of the maximum document placement width and the midpoint of the maximum image width by a distance lx given by lx = (Lo-lc/m)/2・m/(1+m). An image forming apparatus characterized by comprising means for moving the document from above toward the document reference edge side.