JPH041345B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a copying apparatus that employs electrophotography and has means for removing unnecessary charges from the surface of a photoreceptor.

``Prior Art'' In an electrophotographic copying device, a drum-shaped or belt-shaped photoreceptor is charged, and then an electrostatic latent image is formed by exposure, and then the image is transferred to copy paper. ing.

In such a copying device, when a charge is applied uniformly to the entire surface of the photoreceptor in the charging process and then exposed to light, the charge is removed from the area irradiated with light, and in the development process, the area where the charge remains is removed. Toner only sticks to the surface. In this case, processing is performed to avoid wasteful development in areas other than the area where the electrostatic latent image corresponding to the image of the document is formed by exposure, that is, the peripheral area of the electrostatic latent image necessary for copying. First, the size of the copy paper is detected. After charging is performed, charge removal lamps arranged in a row facing the photoreceptor are selectively turned on in accordance with the size of the copy paper. In this way, unnecessary charges on the photoreceptor in areas exceeding the size of the copy paper are removed.

However, when using such a copying device to copy, for example, a B5-size original onto A4-size copy paper at the same magnification, the size of the copy paper is limited to the image area (electrostatic latent formed on the surface of the photoreceptor). (the area of the image that corresponds to the original image). For this reason, there was a problem in that dirt on the document cover in the A4 size area around the document was copied at the same time, and the peripheral portion of the copy paper became inferior.

In order to solve this problem, an unnecessary charge removal device was previously proposed in which a charge removal lamp is lit according to the size of the document (see Japanese Patent Laid-Open No. 59-94770). .

In the unnecessary charge removal device according to this proposal, the 13th
As shown in the figure, for example, eight lamps 2 and 2' are arranged in a row in the axial direction of the photoconductor 1 near the drum-shaped photoconductor 1, and their lighting is controlled according to the size of the document. In other words, when the electrostatic latent image is formed only in the hatched area 1' in the figure, only the lamps 2' excluding the hatched lamp 2 are turned on. The portion of the photoreceptor 1 facing the lamp 2' is decharged immediately before development.

``Problems to be Solved by the Invention'' However, with the unnecessary charge removal device proposed by this proposal, there is no problem when the size of the document is a standard size such as A4 size, but there is a problem when it is not. In other words, when copying a one-size-fits-all document smaller than A4 size and larger than B5 size, for example, the lighting control of lamp 2 should be controlled.
This will be done in either A4 or B5 size. When controlling the lighting of the lamp 2 for an A4 size document, the area where the charge remains is larger than the image area, so dirt and the like around the document will be copied at the same time. On the other hand, when controlling the lighting of the lamp 2 in B5 size, the area where the charge remains is smaller than the image area, so the image will be missing.

Also, recently, copying devices equipped with a reduction/enlargement function have been commercialized. In such a copying device, if the lighting of the charge removal lamp is controlled according to the size of the document, the area where the charge remains will be smaller than the image area in the case of enlarged copying, while the area where charge remains will be smaller than the image area in the case of reduced copying. It gets bigger. Therefore, with the unnecessary charge removing device as illustrated in FIG. 13, if the original size is other than the specified size such as A4 size, or if the copy is to be reduced or enlarged, the copy paper may be inferior or the image may be distorted. There was a problem that some parts were missing.

In view of the above circumstances, it is an object of the present invention to provide a copying apparatus having a charge removing means that can always make the area where charges remain coincident with the image area.

"Means for Solving the Problems" In the present invention, electric charges are uniformly applied to the surface of the photoreceptor, and two sides of the document forming predetermined corners of the platen glass are aligned with each other. Scanning exposure is performed to form an electrostatic latent image on the surface of the photoreceptor so that one of the two sides in the scanning direction of the document is projected near one end of the photoreceptor in a direction perpendicular to the direction of movement of the photoreceptor. In a copying machine that creates an image through the steps of development, transfer, and fixing after forming a photoreceptor, () a plurality of light-emitting elements that can selectively emit light are placed on the surface of a photoreceptor at predetermined positions. The photoreceptors are arranged in series from one end to the other end opposite to the above one end in a direction perpendicular to the direction of movement of the photoreceptors while maintaining a distance of . (a) a first charge removing means that is movable in a direction perpendicular to the direction of movement; a second charge removing means capable of removing charges within a range that covers at least one bridge of the photoconductor and an end of the first charge removing means on the one end side; and (1) moving the first charge removing means. () a copy magnification input means for inputting a copy magnification; () an original size setting means; and () an original size given by the original size setting means and a copy input from the copy magnification input means. a calculation means for calculating the position of one side of the area located on the other end side of the photoreceptor in the image area on the photoreceptor obtained by multiplying the magnification value;
Based on the calculation result of the calculation means, when some of the light emitting elements of the first charge removing means are turned on, the boundary between the light emitting elements that are turned on and the light emitting elements that are turned off is located on one side of the area. unnecessary electrostatic latent image removal control means that controls the moving means and controls the lighting of the first and second charge removal means; () moves integrally with the first charge removal means;
and a detection section having a detection width longer than the arrangement interval of the light emitting elements and shorter than the maximum permissible movement of the first charge removal means; a sensor, and () the first
means for detecting the amount of movement of the charge removing means; (xi)
When the sensor detects the detection portion prior to the control of the unnecessary electrostatic latent image removal control means, the first charge removal means is moved in a predetermined direction (direction B) until the sensor no longer detects the detection part, and then the first charge removal means is moved in a predetermined direction (direction B). By moving the charge removing means in the direction opposite to the above-mentioned predetermined direction (direction A) and again moving it by a predetermined amount from the detected point,
Alternatively, when the sensor does not detect the detection section prior to controlling the unnecessary electrostatic latent image removal control means, the first charge removal means is moved in the opposite direction (direction A) and the predetermined amount is removed from the detected point. home position setting means for positioning the first charge removal means at a home position by moving;
(xii) upon activation of this home position setting means;
Abnormality control means is provided for controlling the movement of the first charge removal means to be stopped when the output from the movement amount detection means exceeds the maximum allowable movement amount.

"Operation" According to the present invention, the boundary between the light-emitting elements of the charge removing means that are turned on and those that are turned off is always accurately located on a predetermined side of the image area. The remaining area will completely match the image area. Furthermore, even if the charge removal means attempts to move in the column direction of the light emitting elements and for some reason tries to move beyond the maximum allowable movement amount, the operation can be stopped, thereby protecting the device. is becoming certain.

"Example" The present invention will be explained in detail with reference to Examples below.

(Overview of Apparatus) FIG. 1 shows the main parts of the copying apparatus of the present invention. In this device, first and second charge removing members 6 and 7 are arranged opposite to the surface of a drum-shaped photoreceptor 5.
are placed respectively. Among these, the first charge removing member 6 includes a lamp, a light emitting diode, etc., and is fixed to a frame (not shown).
The second charge removing member 7, as shown in FIG.
It has a structure in which a plurality of light emitting elements 8 made of light emitting diodes or the like are arranged in rows at intervals on a rod-shaped base 9. This second charge removing member 7 has its light emitting element 8 facing the surface of the photoreceptor 5 and is arranged parallel to its axis, and is perpendicular to the scanning direction of the photoreceptor 5 as shown by arrows A and B. In other words, it is movable in the direction of the column.

For example, as shown in perspective in FIG. 3, when an electrostatic latent image corresponding to the image of the document is formed on the surface of the photoreceptor 5, the first charge removing member 6 is used to form this electrostatic latent image. This will remove the charge in the area to the left of the image area 10 to be imaged. The second charge removal member 7 removes the charge in the area on the right side of the image area 10 when a predetermined part of the light emitting element 8 turns on.

When using this device to remove charges from an area other than the image area 10 in the circumferential direction of the photoreceptor 5, the first
Not only the charge removing member 6 but also all the light emitting elements 8 of the second charge removing member 7 are turned on. The lighting control of the second charge removing member 7 at this time may be performed based on the detection result by detecting the amount by which the photoreceptor 5 has rotated from the home position in the direction of arrow C in FIG. Whether or not the photoreceptor 5 has reached the home position can be detected by detecting the permanent magnet 11 provided on one side thereof by a magnetic sensor (not shown). How much the photoconductor 5 has rotated from the home position in the direction of arrow C can be determined by a transmission-type rotation amount detection sensor 13 formed through a number of slits around a disk 12 provided at the other end of the photoconductor 5. (a so-called rotary encoder).

By the way, in this device, the second charge removing member 7
is movable in the directions of arrows A and B. This device also needs to detect the size of the document. Therefore, these devices will be explained next.

(Moving Means) FIG. 4 shows a device for moving the second charge removing member 7. The second charge removing member 7 is attached to the slide plate 16. The slide plate 16 is guided by a guide (not shown) and is movable in the directions of arrows A and B. A rack 17 is installed at a predetermined location on the slide plate 16.
is provided. The rack 17 has a pinion 1 attached to the output shaft of the stepping motor 18.
It is interlocked with 9. Stepping motor 1
8 rotates forward or backward, the second charge removal member 7 is moved together with the slide plate 16 in the direction of arrow A or B. A light shielding plate 20 for detecting the home position of the second charge removing member 7 is provided at another predetermined location on the slide plate 16. This second charge removal member 7 is always controlled to move several millimeters in the direction of arrow A or B from this home position. The light shielding plate 20 is configured to pass between the light emitting element and the light receiving element of the transmission type position detection sensor 21 as the slide plate 16 moves. The position detection sensor 21 is fixed to a frame (not shown).

(Detection of document size) FIG. 5 shows a document size detection device. In this apparatus, document detection sensors 33 and 34 in the X and Y directions are provided on two predetermined sides of the platen glass 31 to detect the size of the document 32 in the X and Y directions, respectively. These sensors 33 and 34 have a structure in which a large number of so-called reflection type sensors in which pairs of light emitting elements and light receiving elements are placed in close contact with each other are arranged in a row.

In the X-direction original detection sensor 33, among the light rays emitted from the light emitting elements, those reflected by the surface of the original 32 are incident on the corresponding light receiving elements. Here, X ₁ is the fourth
Refers to the sensor located at the farthest left in the diagram.
X _n refers to a sensor located on the platen glass 31 at a position facing the right end of the surface of the original 32. In this manner, the X _n light receiving elements of the X-direction original detection sensor 33 receive the light from the light emitting elements, so that the size of the original 32 in the X direction that is in close contact with the platen glass 31 is detected.

On the other hand, in the document detection sensor 34 in the Y direction, among the light rays emitted from the respective light emitting elements, those reflected by the surface of the document 32 on the platen glass 31 are incident on the corresponding light receiving elements. Here, Y ₁ refers to the sensor located at the lowest end in FIG. 4, and Y _o refers to the sensor located at a position opposite to the upper end of the document 32 on the platen glass 31 in the same figure. In this way, the light from the light emitting element is transmitted to the document detection sensor 34 in the Y direction.
When the Y _o light receiving element receives light, the size of the document 32 in the Y direction which is in close contact with the platen glass 31 is detected.

(Movement of Charge Removal Member) Next, a case will be described in which lighting and movement of the second charge removal member 7 is controlled in this apparatus based on the size of the original 32, the copying reduction ratio, and the size of the copy paper. At this time, it is assumed that the second charge removing member 7 is initially located at the home position. That is, in the initial state, as shown in FIG. 4, after the right end of the light shielding plate 20 of the charge removing member 7 is detected by the position detection sensor 21, the initial value S is
The position is controlled so that it is in a state of movement. In addition, the size of the copy paper in the axial direction of the photoreceptor 5 is L ₁ mm, the size of the original 32 is L ₂ mm, and the second charge is removed per one step (rotation angle when one pulse is supplied) by the stepping motor 18. Let the amount of movement of the member 7 be Rmm, the pitch of the light emitting elements 8 of the second charge removing member 7 be Pmm, and the copying reduction magnification be M as shown in FIG.

In this device, lighting and movement of the second charge removing member 7 are controlled based on the smaller of the range of the image area 10 in the axial direction of the photoreceptor 5 and the size of the copy paper. Image area 10
The range is the value (L ₂ ×M) obtained by multiplying the size L ₂ of the original 31 by the reduction ratio M.

When (L ₂ × M)≧L ₁ , that is, when the range of the image area 10 is equal to or larger than the size of the copy paper, the size L ₁ of the copy paper is divided by the pitch of the light emitting elements 8. An integer N is determined from among the values, and a value Q is determined by dividing the remainder S at that time by the amount R of movement of the second charge removing member 7 per one step by the stepping motor 18.

L ₁ /P=N...Remainder S, S/R=Q (L ₂ × M) < L ₁ , that is, if the range of the image area 10 is smaller than the size of the copy paper, the range of the image area 10 (L ₂ ×M) is divided by the pitch P of the light emitting element 8 to obtain an integer N, and the remainder S at that time is used as the second charge removing member 7 per step by the stepping motor 18. Find the value Q divided by the amount of movement R.

(L ₂ ×M)/P=N...Remainder S, S/R=Q And in either case, based on the integer N, N of the light emitting elements 8 of the second charge removing member 7 is selected from the left side in FIG. The lights up to the first one are turned off, and the other lights are turned on. At this time, when the value Q is 0, as shown in FIG.
Of these, the midpoint between the N-th and N+1-th corresponds to the left side 10A of the image area 10. Therefore, in this case, the second charge removing member 7
will remain at the home position. On the other hand, when the value Q is 1 or more, the N+1-th light emitting element 8 faces the left side of the image area 10, as shown in FIG. 7, for example. Therefore, in this case, a Q pulse is applied to the stepping motor 18 to move the second charge removing member 7 by Q×R in the direction of arrow A.
Then, as shown in FIG.
The middle point between the th one and the N+1 th one coincides with the left side 10A of the image area 10.

Next, a specific example of controlling the lighting and movement of the second charge removing member 7 based on the size of the document in this apparatus will be described. At this time, it is assumed that the second charge removing member 7 is initially located at the home position. Further, the pitch P of the light emitting elements 8 of the second charge removing member 7 is 20 mm, the gap D is 1 mm, and the amount of movement R of the second charge removing member 7 per one step by the stepping motor 18 is set to 20 mm.
Set to 0.25mm.

Under these conditions, for example, a full-size copy of an A4-sized original is A4
Suppose that this is done on a 1-size copy paper. In this case,
The sizes L ₁ and L ₂ of the copy paper and the original in the axial direction of the photoreceptor 5 are both 210 mm, and the copy reduction magnification M is 1. Therefore, the range of the image area 10 (L ₂
×M) is 210 mm, which is equal to the size of copy paper. Dividing the copy paper size L ₁ (210 mm) by the pitch P (20 mm) of the light emitting element 8 gives an integer N of 10.
is obtained, and by dividing the remainder S (10 mm) by the amount of movement R (0.25 mm) of the second charge removing member 7 per step by the stepping motor 18, a value Q of 40 is obtained.

Therefore, in this case, among the light emitting elements 8 of the second charge removing member 7, the tenth ones from the left in FIG. 3 are turned off, and the others are turned on. Also, the stepping motor 18 has 40
Pass is applied, and the second charge removal member 7 is moved in the direction of arrow B by 40×0.25=10 mm. Even if the original is of a size other than the predetermined A4 size, the lighting and movement of the second charge removing member 7 will be controlled in the same way.

(Circuit Configuration of Apparatus) FIG. 9 schematically shows the configuration of the control circuit of this apparatus. This device is equipped with a CPU (central processing unit) 41, and is connected to various parts through a bus line 42 such as a data bus. Among these, a ROM (read only memory) 43 is a memory in which a program for controlling the circuit is written. RAM (Random Access Memory)
Reference numeral 44 stores copy condition data such as copy reduction magnification set on an operation panel (not shown), and also temporarily stores other processing data.
Backed up by batteries (non-volatile memory)
The NVM 45 stores data regarding the current position of the second charge removal member 7. The position of the second charge removal row member 7 can be expressed by the number of pulses applied to the stepping motor 18, how far it has moved in the direction of arrow B in FIG. 3 from the home position. Therefore, NVM45
The data stored in stepping motor 1
This data contains the number of pulses applied to 8.

The operation panel input section 46 is a data input section for inputting various data on the operation panel. The sensor input port 47 is a circuit portion that inputs data output from the position detection sensor 21 and data output from the document detection sensors 33 and 34, processes them, and sends them onto the bus line 42. The motor driver 48 is a circuit that outputs pulses to control the driving of the stepping motor 18. The light emitting element driver 49 is a circuit that controls lighting of the light emitting element 8 of the second charge removing member 7 and the lamp of the first charge removing member 6.

(Basic Operation of the Apparatus) Next, the operation of this apparatus will be explained with reference to a flowchart (FIG. 10). The CPU 41 first monitors whether the original 32 is set on the platen glass 31 (step). This is done by checking whether the presence or absence of the original document 32 is detected by each of the document detection sensors 33 and 34 in the X direction and the Y direction, using data as a detection output. Manuscript 32
is set on the platen glass 31,
The size of the document 32 is detected by the document sensors 33 and 34 in the X and Y directions, and the CPU 41 determines the size of the document 32 based on the detected data (step). As a result, the size of the document 32 is determined not only when it is a predetermined size such as A4 size, but also when it is not.

Next, the CPU 41 calculates the position of the left side 10A of the image area 10 on the surface of the photoreceptor 11 based on the size data in the Y direction of the original 32, the size data in the same direction of the copy paper, and the copying reduction ratio (step). As already explained, this calculation is
This is performed by calculating the number of pulses to be applied to the stepping motor 18 while the second charge removal member 7 is located at the home position.

Next, the CPU 41 reads the previous applied pulse number data written in the RAM 45 and determines whether the number of pulses corresponding to this data is the same as the pulse quality to be applied to the stepping motor 18 this time. (step). If they are the same, it means that the current position of the second charge removing member 7 is the same as the previous position. This kind of thing is
This can occur when copying an original of the same size as the previous original under the same copying conditions as the previous one. If they are not the same, the CPU 41 next determines whether the position detection sensor 21 is in an off state (step). Here, when the position detection sensor 21 is in an off state, it means that the light shielding plate 20 is located to the left of the position detection sensor 21, as shown in FIG. On the other hand, when the position detection sensor 21 is in an on state, it means that the light shielding plate 20 is shielding the position detection sensor 21 from light.

When the position detection sensor 21 is on (step), the motor driver 48 is driven in the reverse direction, and the stepping motor 18 starts to rotate in the reverse direction (step). Then, the light shielding plate 20 is moved in the direction of arrow B together with the slide plate 16. At this time, the CPU 41 monitors whether the position detection sensor 21 is turned off (step). When turned off, the stepping motor 18 is stopped. As a result, the light shielding plate 20 is positioned to the left of the position detection sensor 21 in FIG. 4. The subsequent operation is the same as when the position detection sensor 21 is in the OFF state in step.

When the position detection sensor 21 is turned off in this way, or when the position detection sensor 21 is turned off from the beginning of the step, the motor driver 48 is driven in the forward direction, and the stepping motor 18 normal rotation starts (step). The light shielding plate 20 is moved in the direction of arrow A together with the slide plate 16. At this time, the CPU 41 monitors whether the position detection sensor 21 is turned on (step). When it is turned on, the second charge removing member 7 is then moved by an amount corresponding to the initial value S, and the stepping motor 18 is stopped (step). As a result, the second charge removing member 7 is located at the home position together with the light shielding plate 20 and the like.

Next, the CPU 41 determines whether the number of pulses to be applied to the stepping motor 18 this time is 1 or more (step). If it is 1 or more,
The CPU 41 sets the number of pulses to be applied this time in a built-in counter (step). Next CPU4
1 causes the motor driver 48 to rotate forward by one pulse, causing the stepping motor 18 to rotate forward by one step (step), and also decreases the counter by one (step). Next, the CPU 41 determines whether the set number of the counter is 0 or not (step). If not 0, stepping motor 1
8 is further rotated forward by one step, and the counter becomes 1 again.
One step down (step,). When the set number of the counter becomes 0 (step;
Y), the CPU 41 writes data containing the current number of applied pulses into the RAM 45 (step).

If the number of pulses to be applied this time in the step is not 1 or more, that is, 0, there is no need to move the second charge removing member 7.
The CPU 41 writes the current number of applied pulses, that is, data whose content is 0, to the RAM 45 (step).

(Position detection sensor and light shielding plate) Here, using FIG. 11, position detection sensor 21
The relationship between the light shielding plate 20 and the light shielding plate 20 will be explained in more detail.

First, in the case of this embodiment, the maximum amount of movement of the charge removing member 20 is sufficient to be approximately a length corresponding to the pitch P of the light emitting element 8 (FIG. 2). When the width of the light shielding plate 20 is set to be slightly longer than this P, when the charge removing member 20 is closest to the direction of arrow A, a state as shown in FIG. 11a is obtained. Here, when returning the charge removing member 20 to the home position,
This is moved in the direction of arrow B, and the position detection sensor 21 is suddenly turned off as shown in FIG. Thereafter, the charge removing member 20 is brought to rest at a position where the right end 20 ₁ of the light shielding plate 20 has moved in the direction of arrow A by a distance S from the detection point 21 ₁ of the position detection sensor 21, as shown in FIG. Now, charge removal member 2
0 is set to the home position. This S
may be, for example, several steps of a stepping motor.

(Abnormality Detection) Here, in FIG. 11b, the charge removing member 2
Even if 0 moves in the direction of arrow B, the position detection sensor 2
1 may not turn off. This may be due to a malfunction of the position detection sensor 21 or malfunction due to external noise. This may also occur if the stepping motor 18 fails and does not move the charge removal member 20 at all.

The same thing can be said when moving from state b to state c in FIG. 11. In either case, the charge removing member 20 may overrun, or copying may be performed without the device operating normally.

In order to prevent this, it is necessary to detect abnormalities in the operation of the apparatus and notify the operator of the abnormalities and take appropriate measures.

In this embodiment, at the stage when the charge removing member 20 moves from the state 11a to the state shown in FIG. compare. The data corresponding to the maximum allowable movement amount is, for example, a value obtained by adding a certain margin to the maximum number of pulses supplied to the stepping motor 18 during this movement. Therefore, in the case of normal operation, the width actually detected by the position detection sensor on the light shielding plate, that is, the detection width is longer than the pitch P of the light emitting element 8 (FIG. 2).
And it is shorter than this maximum allowable movement amount.

That is, this device detects an abnormality, stops the movement, and issues a certain alarm when the charge removal member 20 moves beyond this maximum allowable movement amount when returning the charge removal member 20 to the home position. It works like this. The detailed flowchart of its operation is shown in the first
Shown in Figure 2.

This shows the flow from the step in FIG. 10 in more detail. In FIG. 12, which is a flowchart, "timer set" refers to storing a value corresponding to a predetermined maximum allowable movement amount in a register or the like. Abnormality detection is performed by subtracting the number of drive pulses supplied to the stepping motor from the value in this register and monitoring whether this value becomes zero.

In the present invention, the abnormality detection means is, for example, NUN45 (9th
Figure).

In the flowchart, first it is determined whether the position sensor is off (step). This is the process when the charge removing member is in the state shown in FIG. 11a. Set the timer here (step),
While confirming that the position sensor is turned on (step), subtract 1 from the timer (step) and reversely rotate the stepping motor one step at a time (step). If the position sensor turns off (step) before the timer reaches zero (step), it is assumed that the charge removing member has moved normally, and the timer is stopped (step). Next, the stepping motor is also stopped (step).
This results in the state shown in FIG. 11b. Additionally, if the timer reaches zero before the position sensor is turned off (step), the stepping motor is immediately stopped (step), and an abnormality flag is set for processing the abnormality (step). step). After this, a message will be sent to the operator indicating that an abnormality has occurred to prompt the operator to repair the problem.

Further, when the charge removing member is in the state shown in FIG. 11b, a timer is set (step), and 1 is set from the timer while checking whether the position sensor is turned on (step). The stepping motor is rotated forward by one step (step), and it is monitored whether the timer reaches zero in the same manner as described above (step). If an abnormality occurs, the process moves to the previously described steps to handle the abnormality.

Further, when the position sensor is normally turned on, the timer is stopped (step), the motor is stopped (step), and the charge removing member is set at the home position.

In this way, by detecting abnormalities in the moving state of the charge removal member and taking appropriate measures, it is possible to prevent the motor from heating up and burning out, or from copying with poor charge removal. .

"Effects of the Invention" As explained above, according to the present invention, the area where the charge remains can always be made to match the image area, so the copy paper will not look inferior or the image will not be missing, and the image will be clean. Able to make accurate copies. Moreover, malfunction of the charge removing means can be reliably detected, resulting in high reliability. Further, since the developer does not adhere to unnecessary portions during the developing process, cleaning failures do not occur in these portions, and the subsequent copying is not adversely affected. Furthermore, the developing device and the developer are not subjected to unnecessary abuse, the durability is improved, and it is economical.

[Brief explanation of drawings]

1 to 10 are for explaining one embodiment of the present invention, of which FIG. 1 is a perspective view showing the main parts of the copying device, and FIG. 2 is a perspective view of the light emission of the second charge removing member. FIG. 3 is a plan view showing an example of removing unnecessary charges on a photoreceptor; FIG. 4 is a perspective view showing essential parts of the second charge removal member moving device; FIG. The figure is a plan view showing the main parts of the document size detection device, FIGS. 6 to 8 are diagrams shown to explain lighting and movement control of the second charge removal member,
The figure is a block diagram showing the main parts of the electric circuit of this copying device, FIG. 10 is a flowchart showing the operation of the device in controlling the movement of the second charge removing member, and FIG. 11 is a position detection sensor and light shielding during its operation. FIG. 12 is a partial plan view showing the positional relationship of the plates, FIG. 12 is a flowchart of a program showing the abnormality detection operation, and FIG. 13 is a perspective view showing an example of a conventional unnecessary charge removal device. 5...Photoreceptor, 6...Fixed charge removal member,
7...Movable charge removal member, 8...Light emitting element, 1
0... Image area, 10A... Left side (predetermined side),
18... Stepping motor, 20... Light shielding plate,
21... Position detection sensor, 31... Platen glass, 32... Original, 33, 34... Original detection sensor, 41... CPU, 43... ROM, 44, 45
...RAM, 46...Operation panel input section, 47...
...Sensor input port, 48...Motor driver,
49...Light emitting element driver.

Claims (1)

[Scope of Claims] 1. A charge is uniformly applied to the surface of a photoconductor, and scanning exposure is performed with the two sides of the document that form predetermined corners of the platen glass aligned with each other. After forming an electrostatic latent image on the surface of the photoreceptor so that one of the two sides in the scanning direction is projected near one end of the photoreceptor in a direction perpendicular to the direction of movement of the photoreceptor, In a copying machine that creates an image through each process of development, transfer, and fixing, a plurality of light-emitting elements that can selectively emit light are kept at a predetermined distance from the surface of the photoreceptor while the photoreceptor is moved. The light emitting elements are arranged in series from one end of the photoreceptor and the other end on the opposite side in a direction perpendicular to the direction of movement of the photoreceptor, and are movable in the direction perpendicular to the direction of movement of the photoreceptor by at least the arrangement interval of these light emitting elements. a first charge removing means fixedly disposed at a predetermined distance from the surface of the photoreceptor, and arranged between one end of the photoreceptor in a direction perpendicular to the moving direction of the photoreceptor and a first charge removing means on the one end side; 1
a second charge removing means capable of removing charges within a range that covers at least an end of the charge removing means; a moving means for moving the first charge removing means; and a copying magnification for inputting a copying magnification. an input means, an original size setting means, and a photosensitive area in an image area on the photoreceptor obtained by multiplying the original size given by the original size setting means and the copy magnification value inputted from the copy magnification input means; a calculating means for calculating the position of one side of the region located on the other end side of the body; and a calculating means for calculating the position of one side of the region located on the other end side of the body; removing unnecessary electrostatic latent images by controlling the moving means so that the boundary between the light emitting element and the light emitting element that is turned off is located on one side of the area, and controlling the lighting of the first and second charge removing means; a control means; a detection section that moves integrally with the first charge removal means and has a detection width that is longer than the arrangement interval of the light emitting elements and shorter than the maximum allowable movement amount of the first charge removal means; a sensor fixed to the main body of the copying machine for detecting the position of the detection section; a means for detecting the amount of movement of the first charge removing means; and a sensor prior to controlling the unnecessary electrostatic latent image removing control means. When the sensor detects the detection part, move the first charge removing means in a predetermined direction (direction B) until the sensor no longer detects the detection part, and then move the first charge removing means opposite to the predetermined direction. direction (direction A) and then a predetermined amount from the point where it was detected again, or when the sensor has not detected the detection section prior to the control of the unnecessary electrostatic latent image removal control means. home position setting means for positioning the first charge removing means at a home position by moving the first charge removing means in the opposite direction (direction A) and moving it by the predetermined amount from the detected point; abnormality control means for controlling the movement of the first charge removal means to be stopped if the output from the movement amount detection means exceeds the maximum allowable movement amount when the motion setting means is activated. A copying device characterized by: