JPS63264780A - Variable magnification electronic copying machine - Google Patents

Abstract

PURPOSE:To uniformize the exposure distribution on an image surface, by independently moving a projective lens in the direction of its optical axis and in the width direction of a photosensitive body and independently controlling the light shielding quantities of both light shielding plates by interlocking with the movement of the projective lens. CONSTITUTION:The image of an original 2 which is positioned to a reference position along a prescribed edge on an original placing table is projected on a photosensitive body by means of a projective lens 3. The titled machine is provided with a 1st moving mechanism which moves the lens 3 in the direction of its optical axis, a 2nd moving mechanism which moves the lens 3 in the width direction of the photosensitive body 4, a 1st control means which separately controls the moving quantities of both of the moving mechanisms so as to form the image of the original positioned to the reference position at a prescribed position on the same side of the reference position, and a 2nd control means which separately controls the light shielding quantities of two light shielding plates which are independently movable by interlocking with the control of the 1st control means. Therefore, the projective lens 3 is separately moved in the direction of its optical axis and the width direction of the photosensitive body and the exposure distribution on an image surface can be uniformized easily.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a circular magnification electronic copying machine, and more particularly to exposure range correction accompanying movement of a projection lens of the copying machine.

BACKGROUND OF THE INVENTION Various mechanisms have been proposed and provided as variable magnification electronic copying machines. Among these mechanisms, when focusing on the relationship between the position of the original placed on the original glass and the position of the copy paper ejected from the copy paper, it can be roughly divided into the following three types of mechanisms. can.

(I) Align the original on the front side, eject the copy paper on the back side (m Align the original on the back side, eject the copy paper on the front side (2) Align the original center,
Copy paper center ejection Here, the front side and the back side refer to the front side and back side in a copying machine where the scanning direction of the document table or optical system or the conveying direction of the copy paper is lateral to the user facing the copying machine. This is the positional relationship seen from the user.

As an example of such a copying machine, as shown in FIG.
3) schematically shows a mechanism for projecting onto a rotating photoreceptor (4). The image formed on the photoreceptor (4) is developed by a known mechanism (not shown) and transferred to a copy set (5).

In this figure, for the following explanation, the optical axis direction of the projection lens (3) is the X direction, the papermaking speed direction of the original (2) or copy paper (5) is the Z direction, and the direction perpendicular to both directions, that is, The width direction of the photoreceptor (4) is defined as the Y direction.

The three types of mechanisms described above are shown in Figure 2, which is viewed from the Z direction in Figure 1.
This will be further explained using FIGS. I, II, and III.

In FIG. 2, the left side from which the operation panel portion protrudes is the front side, and the right side is the back side.

Figure 2 shows the image formation position on the photoconductor and the projection lens position (dot) when an original with widths al and a2 is projected at magnification +n+ (solid line indicates optical path) and magnification m2 (dotted line indicates optical path). The relationship between document width, magnification, and imaging width is set as shown in Table 1. Further, the copy paper is conveyed so as to match the position indicated as the image forming width.

(Left below) Table 1 As can be seen from these figures, each of the conventional methods has its advantages and disadvantages. That is, in the method shown in FIG. 2, it is easy to handle the original because the front side is aligned, but it is difficult to handle the copy paper because it is ejected to the back side. The difficulty of obtaining copy paper increases further when a sorter or the like is connected to the copying machine. Furthermore, when copy paper jams, it is necessary to insert one's hand deep inside the copying machine, making it difficult to clear the jam.

Although the method shown in FIG. 2H makes it easier to handle the copy paper, it requires a button to align the original.

The method shown in Figure 2 III is an intermediate method between the above two methods, and has the disadvantages of both methods, except that it requires positioning an unmarked document in the center of the document placement glass. Therefore, a cursor for positioning is essential.

If you still want to change the magnification, the methods shown in Figure 2 ■ and ■ move the projection lens not only in the optical axis direction (X direction) but also in the width direction of the photoreceptor (Y direction). The amount of directional movement is determined only by the magnification. That is,
The amount of movement in the X direction and the amount of movement in the Y direction are controlled based on a unique correlation. In the method shown in FIG. 2 (2), the magnification is changed by moving the projection lens only in the X direction.

On the other hand, the uses of copying machines have diversified in recent years, and they are used not only to make copies of a single original, but also to create multiple copies of bound documents from multiple originals. A binding margin is necessary to create a bound document from a series of copies, but since manuscripts do not necessarily have margins with a binding margin in mind, users can work must be done to create it. However, with conventional copying machines, the position of the image on the copy is uniquely determined by the alignment reference edge of the document, so the user has to create a binding margin by positioning the document one by one from the alignment reference edge. It was a cumbersome task to shift the parts.

In order to improve this problem, the movement of the projection lens in the optical axis direction and in the width direction of the photoconductor is controlled independently, and this allows the user to easily adjust the document placement reference position and the imaging position on the photoconductor. It is conceivable to align the documents to the edges on the same side, and to create an arbitrary binding margin while keeping the document aligned with a predetermined reference position.

However, when adopting such a configuration, it is necessary to appropriately correct the exposure amount distribution in the width direction of the photoreceptor.

Conventionally used exposure compensation mechanisms include those in which a light shielding plate is fixedly arranged, and those in which a single movable light shielding plate is arranged in the optical path of the projection lens and is moved as the magnification changes. However, these mechanisms cannot appropriately correct the exposure dose distribution in the above-described projection apparatus in which the projection lens is moved independently in the direction of its optical axis and in the width direction of the photoreceptor.

The present invention has been made in view of the above points, and it is an improved projection apparatus in which the projection lens is moved independently in the direction of its optical axis and in the width direction of the photoreceptor, and it is an object of the present invention to appropriately correct the exposure distribution. The purpose is to provide a mechanism that allows you to do so.

The variable magnification electronic copying machine of the present invention has a mechanism for independently moving the projection lens in the direction of its optical axis and in the width direction of the photoreceptor;
It has light shielding plates that are arranged on both sides of the photoconductor width direction of the projection lens and can move independently from each other, and an exposure distribution correction mechanism that independently controls the amount of light shielded by both light shielding plates in conjunction with the movement of the projection lens. This achieves the above objective.

Embodiment First, an improved method of moving the projection lens, which is the premise of the present invention, will be explained.

Figure 3 shows the copying machine viewed from the Z direction in the same way as Figure 2 to show the positional relationship between the original (2), the image formation position on the photoreceptor (4), and the projection lens (indicated by a dot). A schematic diagram,
Using this diagram, we will first explain the principle behind positioning the original to the front and ejecting the copy paper to the front.

In FIG. 3, al and a2 indicate the width of the document, and bt.

b2. b3 indicates the width of the image formed on the photoreceptor, in other words, the width of the copy paper used. -1, the solid line optical path has a magnification m
1, the dotted optical path is at magnification m2, and the dot at the intersection of the optical paths indicates the lens position.

The projection lens is moved in the width direction (Y direction) of the photoreceptor in order to project the image of the document positioned at the front base thread edge P so that its edges are aligned with the front reference edge 9 on the photoreceptor. When changing the magnification at the same time, set the projection lens with an optical axis force of 1ipl.
Although it is also moved (in the X direction), the movements in the X and Y directions are carried out independently.

Here, when projecting the alO original onto the imaging positions of bt and b2, and when projecting the original of a2 onto b2. When projecting onto the image forming position b3, original a, image forming position 2 magnification m, lens position (
Table 1 shows the relationship between x and γ). Note that the lens position is defined as the origin (o, o) when an original document of al is projected onto an imaging position of bl at a magnification of m1. Further, ΔL is a change in conjugate distance when changing the magnification.

Table 1 By moving the projection lens in the Y direction in this manner, the image formation position can be aligned with the near side reference edge QK on the photoreceptor, thereby allowing the copy paper to be ejected to the near side. It should be noted that the above movement amount can be calculated by a person skilled in the art in accordance with a specific 4F configuration.

Next, using FIG. 4, we will explain how to create a binding margin. Fig. 4 is written in the same way as Fig. 3, and in this figure, when projecting an original with a width a onto a photoreceptor, the projection lens is moved in the Y direction by ΔY, and an image is formed at the position indicated by the dotted optical path. On the other hand, copy paper is normally conveyed so as to match the image formation position. This makes it possible to form a margin of Δd for the binding allowance. The amount of movement of the projection lens is calculated using the following formula, where m is the magnification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A copying machine embodying the present invention will be described in more detail below with reference to the drawings.

FIG. 5 is a central sectional view of the electrophotographic copying machine, and the original is positioned on the original placing glass (10) so that it is aligned with the front side (the front side of the paper). The image of the original is displayed by the lamp (11) and the first
A first scanning system consisting of a mirror (12) and a second mirror (12);
3) and a second scanning system consisting of a projection lens (1).
4) Projected onto the photoreceptor (4) via the third and fourth mirrors (15x16). The photoreceptor (4) is connected to the charger (1
7), an electrostatic latent image is formed by projecting the image, and this electrostatic latent image is transferred to the developing device (18).
It is made into a toner image. The toner image is stored in two cassettes) (1
After being transferred onto a copy sheet fed from one of the 9x20 sheets, the image passes through a fixing device (21) and is discharged onto a tray (22).

On the other hand, the photoreceptor (4) after the transfer is connected to the static elimination charger (23).
It is cleaned with a cleaning mount (24) and an eraser lamp (25) in preparation for the next copy.

In the copying machine described above, the projection lens (14) is moved in the optical axis direction (X direction) and the photoreceptor width direction (Y direction) by the mechanism shown in FIG. In addition, the mechanism shown in Figure 6 also has third and fourth mirrors (
15) Also perform the movement in (16).

In FIG. 6, the projection lens (14) is mounted on a Y-direction moving table (
30), and the Y-direction moving table (30) is held movably in the Y-direction by a guide rod (32) and a guide screw (33) on the X-direction moving table (31). The guide screw (33) is connected to a motor (34), and its rotation moves the Y-direction moving table (30).

On the other hand, the X-direction moving table (31) has two guide rods (3
5) It is held movably in the X direction by (36), and the motor (
37) Wire (3) connected via K pulley (38)
9), it is moved in the X direction. The driving force of the motor (37) is also transmitted to the cam (4) via a gear train, and the cam (40) is driven parallel to the X direction by a guide rod (41) and a guide plate (42). The cam followers (44) K of the third and fourth mirror holders (43), which are movably held, are in contact with each other.The third and fourth mirror holders (43) are held together by springs (45) so that the projection lens (
14).

With the above configuration, the projection lens (14
) is determined, the motors (34) (37) rotate according to the moving vehicle to move the projection lens (
14) by a predetermined amount and move the third and fourth mirrors (
15) Move (16) in a direction parallel to the X direction.

The amount of movement of the projection lens is determined from two parameters of copy paper size, magnification, and original size in the case of front alignment of originals and front ejection of copy paper. Therefore, three control configurations are possible for the configurations of FIGS. 5 and 6.

The first control type determines the amount of movement based on the copy paper size and magnification. The copy paper size and magnification are respectively instructed using selection keys on the operation panel. The specified copy paper size and magnification are determined by the microcomputer-MC as shown in FIG.
The amount of movement in the X direction is independently calculated from only the magnification, and the amount of movement in the Y direction is calculated from the magnification and copy paper size, and these are supplied to an X direction drive circuit and a Y direction drive circuit, respectively. Both drive circuits rotate the motors (34) and (37) to a predetermined degree, respectively, to drive the projection lens (14) and the third and fourth mirrors (15).
E16) to a predetermined position.

For example, when a user wants to copy a B4 size original to A4 size, select A4 size copy paper and a magnification of x0.8, and align the original with the front side reference sheet of the original glass. Make a copy. As a result, the copy paper is discharged to the front side of the tray (22). Incidentally, since the document size that can be copied can be calculated from the copy paper size and the magnification signal, the document size that can be copied in close-up may be displayed based on this calculation on a display device provided around the document placement glass.

The second control type determines the amount of movement based on the document size and magnification. The document size is detected or indicated. Various methods can be considered for detecting the document size, one example of which is shown in FIG.

FIG. 8 is a sectional view of the document placement glass (10) and the document cover (50) viewed from the Z direction, and multiple detectors (51) (51)...・・・・・・
is provided. As shown in the enlarged view of the detector (51), a light emitting element (53) and a light receiving element (54) are embedded in the upper part of a transparent body (52), and the light from the light emitting element (53) is transmitted to the original (2). ) is reflected by the original (2) and reaches the light receiving element (54), but if there is no original, the transparent body (
52) and the document placement glass (10) and does not reach the light receiving element (54). Therefore, the document size can be detected based on the outputs of these plurality of light receiving elements.

The document size detected or instructed in this way and the instructed magnification are input to the microcomputer MC, as shown in FIG. 9, and the motors (34) (37 ) to drive the projection lens (14)
and move the third and fourth mirrors (15) and (16) by a predetermined amount.In this case as well, the size of the imaging range can be calculated from the document size and magnification, so it is easy to fit the imaging range. The available copy paper sizes may be automatically selected or displayed.

The third control type determines the amount of movement based on the copy paper size and the original size. The copy paper size and original size are indicated or detected in the same manner as described above, and are input to the microcomputer MC as shown in FIG. In this case, it must be noted that the amount of movement in the X and Y directions is calculated based on the parameters of both the copy paper size and the document size.

Next, a case will be described in which the projection lens is moved in the Y direction to create a binding margin. The binding margin Δd explained in FIG. 4 is input as an image shift amount using an input device as shown in FIG. 11, for example.

Figure 11 shows the binding margin creation section installed on the operation panel.
By pressing the right shift key (60) and the left shift key (61) the fiLED indicator (62) (62)
. . . to specify the amount of movement for the binding margin by moving the light emitting position. For example, when the image forming position is moved to the second position from the right, a signal is generated to move the imaging position to the right by 1.5 crn.

The Y direction movement amount Δy=Δd/(m+1) of the projection lens is calculated from the designated image shift amount Δd and the designated magnification m.

Figure 12 is a circuit diagram when a conventional copying machine of the type shown in Figure 2 (■) is equipped with a binding margin creation function, and the amount of movement in the Y direction is calculated from the designated binding margin and magnification as described above. Y, Y
A directional drive circuit operates the motor (34). On the other hand, in the X direction, the amount of movement is determined only by the magnification and the motor (37) is operated.

Similar to the example shown in FIG. 12, the copying machines of the types I and II shown in FIG. 2 can also have a binding margin creation function.

In this way, by adding the function of arbitrarily moving the projection lens of the present invention in the Y direction independently of the X direction to the conventional method, a partial effect of the present invention is achieved in that the binding margin can be easily created. It is possible.

However, if the function of creating a binding margin is combined with the functions of aligning the front side of originals and discharging the front side of the copy sheet, the copying machine will be more efficient in terms of its construction and will have the greatest effect. FIG. 13 shows a circuit in which a binding margin creation function is added to the circuit shown in FIG. This is done by adding Δy calculated from the shift amount and the magnification. By doing this, it is possible to achieve both the convenience of aligning the front side of the original and ejecting the copy sheet on the front side, and the easy creation of a binding margin. It goes without saying that a binding margin creation function can be added to the control mode shown in FIG. 10 in the same manner. In this case, calculate the magnification from the copy paper size and original size,
Processing is performed in which Δy is calculated from this magnification and the designated image shift amount, and a Y-direction movement opening for alignment is calculated from the copy paper size and original size, and the two are added.

Now, the present invention is for appropriately correcting the exposure dose distribution in the above-mentioned copying machine. First, a general explanation of the exposure dose distribution will be given. FIG. 14 is a diagram generally explaining the exposure amount distribution, and the brightness is uniform on the document surface p).
ux], the brightness Em of the image plane (I) is expressed as follows. Here, k is the transmittance of the original glass,
[ is the reflectance of the mirror, which is composed of four mirrors.

, τ is the transmittance of the projection lens (L), η is the aperture efficiency of the projection lens, θ is the angle of view of the projection lens, FNO is the brightness of the projection lens, and m is the magnification. If the constant term in the above equation is represented by C, then the relative blackness at the image plane (I) is proportional to η·cas'θ.

Considering the case where slit regulation is performed on the original side, the exposure theory (xsec) of the image plane (I) is Lm = Em-
d, m.

It is expressed as k. Here, d is the slit width V and the circumferential speed of the photoreceptor. Substituting the above Em into this, it becomes.

The magnification used in ordinary copying machines is approximately 07 to 14. In this case, the term m/(1+m)2 becomes approximately 0.25 and can be considered constant. , therefore, the image plane m O
Th light fjlLm is C “・η” CG in Lm! l'θ・
Eo (C" is a constant), which is proportional only to η and 4θ.

In reality, it is necessary to keep the exposure distribution in the Y direction on the image plane constant, so that the illuminance distribution on the document surface is inversely proportional to η cos'θ, as shown by the dotted line in Figure 14. Set.

Based on the above points, when considering the time distribution on the image plane when the movement in the Y direction shown in Fig. 3 is performed, Fig. 15 shows that
As shown in Figure 16.

FIG. 15 shows the image plane exposure distribution when the projection lens is moved by γI in the Y direction while the magnification remains ml, in comparison with the case where y=o. As is clear from the figure, when moving in the Y direction, the exposure aperture distribution becomes uneven in the Y direction.

FIG. 16 shows the image plane exposure amount distribution when the projection lens is moved in the Y direction by γ2 and y3 at a magnification of m2, and the exposure amount distribution is uneven in the Y direction as in FIG. 15.

Uneven exposure distribution causes exposure unevenness, which is a problem that must be solved. One possible measure is to move the document surface illuminance by γ1+Y2+γ3, respectively, as shown by dotted lines in FIGS. 15 and 16, while maintaining its distribution. This means moving the illumination lamp in its longitudinal direction. However, this strategy requires illumination lamps longer than the maximum document width and still
This has many disadvantages, such as the need to mount a mechanism for longitudinal movement in the scanning system.

Therefore, in the embodiment, the light shielding mechanism shown in FIGS. 17 and 18 is adopted. This light shielding mechanism works with the projection lens (
A light shielding plate (14) that is arranged on the front or rear surface of the projection lens (14) and independently blocks light from a part of the projection lens (14) in the Y direction.
70A) (70B).

In FIGS. 17 and 18, the light shielding plate (70A) (70
B) are rotatably held by support shafts (71A) (71B) provided at symmetrical positions in the width direction of the photoreceptor with respect to the optical axis, and gears (72A) ( 72B
) is installed. This gear (72A) (72B)
is the motor (74A) via the gear (73A) (73B)
(74B), and are independently rotated by the motors (74A) and (74B), respectively.
) is designed to block light. Light shielding plate (70A) (7
There are detection switches (75A) (75B) on the movement path of 0B).
is placed to detect the reference position.

The amount of rotation of the light shielding plates (70A) (70B) depends on the projection lens (
As with the moving port in 14), from the two parameters of copy paper size and original size magnification, and when creating a binding margin, from these two parameters plus the binding margin,
Each is calculated independently. 19.20 and 21 show that the parameters of the copy paper size and magnification, the original size and magnification, and the copy paper size and original size are input to the microcomputer MC, and the parameters for the light shielding plates (70A) and (70B) are calculated independently. An example is shown in which the amount of rotation is determined by the amount of rotation, and the motors (74A) and (74B) are independently driven by the amount of rotation via a motor drive circuit. Still, Figure 22 shows the light shielding plate (70A) based on the copy paper size, original size, and image shift area.
) (70B) is shown. Similarly, the first
It is clear that the amount of image shift can be added to Figure 9.20.

FIG. 23 shows that the image plane exposure distribution is well corrected with the above configuration. In Figure 23, the Y direction mover is 0 and γ1.
This figure shows the difference in exposure distribution between the projection lens (14) viewed from the optical axis direction in the case of 1 and the presence or absence of a shading plate in the case of a moving door. It can be seen that the exposure dose distribution on the image plane is improved.

The examples in Figures 17 and 18 are light shielding plates (70A) (70B)
is rotated around the support shafts (71A) (71B) parallel to the optical axis, but as shown in Fig. 24, it rotates in both the optical axis direction (X direction) and the width direction of the photoreceptor (Y direction). The light shielding plate (7
0A') (70B') may be rotated.

It is also possible to slide the light shielding plate independently.

Although the embodiments described so far relate to the copying machine of the type shown in FIG. As shown in the figure, there is a copying machine with a slightly different configuration of the scanning optical system, and as shown in Figure 26, there is an endless belt-shaped photoreceptor (on which the image of the original is stretched on a flat surface (four flashes are exposed). It is clear that the present invention can also be applied to full exposure type copying machines.

Effects As detailed above, the present invention provides a projection system in a variable magnification electronic copying machine that projects an image of a document positioned at a reference position along a predetermined edge of a document table onto a photoreceptor using a projection lens. A first moving mechanism that moves the lens in the optical axis direction; a second moving mechanism that moves the projection lens in the photoconductor width direction; a first control means for independently controlling each of the movers of the two moving mechanisms so as to form an image at a predetermined position; of the light shielding plate and the first light shielding plate.
Since the projection lens is provided with a second control means that independently controls the amount of light shielded by the two light shielding plates in conjunction with the control means, the projection lens moves independently in the direction of its optical axis and in the width direction of the photoreceptor. Despite this, it is possible to easily equalize the image plane exposure amount distribution according to the movement.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a copying machine for defining the directional relationship according to the present invention; FIGS. 2 and 2 are diagrams I, II, and I [I is a diagram for explaining the state of the optical path of a conventional copying machine; 3 and 4 are diagrams for explaining the movement of the projection lens according to the present invention, FIG. 5 is a longitudinal sectional view of an electrophotographic copying machine to which the present invention is applied, and FIG. 6 is the movement of the projection lens. A plan view showing the mechanism;
7, 9, 10, 12, and 13 are block diagrams illustrating the control mode for the movement of the projection lens, FIG. 8 is a diagram showing an example of the original size detection mechanism, and FIG. 11 14 is a diagram illustrating the relationship between the illuminance distribution on the document surface and the exposure distribution on the image plane. FIGS. 15 and 16 are diagrams showing the Y of the projection lens. Diagrams showing variations in image plane exposure amount distribution due to directional movement, Fig. 17, Fig. 1
FIG. 8 is a plan view and side view for explaining the light shielding mechanism of the projection lens, FIGS. 19, 20, 21, and 22 are block diagrams for explaining the control form of the light shielding mechanism, and FIG. 23 is a block diagram for explaining the control form of the light shielding mechanism. 24 is a diagram showing another embodiment of the light shielding mechanism, and FIGS. 25 and 26 are diagrams showing the configuration of another copying machine to which the present invention can be applied. FIG. 2... Original 3, 14... Projection lens 4
... Photoreceptor 5 ... Copy paper 34 , 37 ,
74A, 74B... Motor 70A, 70B... Light shielding plate. Applicant: Minolta Camera Co., Ltd. Figure 6 Figure 7 Figure 8 Figure 9 Figure 1O Figure 1Z Figure 13 Figure 1 F1 Figure 1Q Figure 20 E 21 Figure 22 Figure 23

Claims (1)

[Claims] 1. In a variable magnification electronic copying machine in which an image of a document positioned at a reference position along a predetermined edge of a document table is projected onto a photoreceptor by a projection lens, the projection lens is aligned with the optical axis. a first moving mechanism that moves the projection lens in the width direction of the photoreceptor; a second moving mechanism that moves the projection lens in the width direction of the photoreceptor; a first control means that independently controls the amount of movement of each of the moving mechanisms so as to form an image; and two light shielding plates arranged on both sides of the projection lens in the width direction of the photoreceptor and movable independently of each other. A variable magnification copying machine characterized by comprising: a second control means that independently controls the amount of light shielded by each of the two light shielding plates in conjunction with the first control means; 2. The second control means 9. The variable magnification electronic copying machine according to claim 8, wherein the amount of light shielded by the light shielding plate is controlled depending on copy paper size and magnification. 3. The variable magnification electronic copying machine according to claim 8, wherein the second control means controls the amount of light shielded by the light shielding plate depending on the document size and magnification. 4. The variable magnification electronic copying machine according to claim 8, wherein the second control means controls the amount of light shielded by the light shielding plate depending on the copy paper size and the document size. 5. The variable magnification electronic copying machine according to claim 8, wherein the second control means controls the amount of light shielding of the light shielding plate based on the amount of image shift instructed for creating a binding margin.