JPH041346B2 - - 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 the entire surface of the photoreceptor is uniformly charged in the charging process and then exposed to light, the charge is removed from the areas irradiated with light, and in the development process, the areas where the charge remains are 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). .

With this proposal, in the unnecessary charge removal device, the 14th
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. It's summery. That is, 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 in this proposal, there is no problem when the document size is a standard size such as A4 size, but there is a problem when it is not. In other words, it is smaller than A4 size and
When copying a one-size-fits-all document larger than B5 size, the lighting control of lamp 2 should be set to A4 size.
It will be done in either size 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 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 removal device as illustrated in FIG. 14, 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 these circumstances, it is an object of the present invention to provide a copying apparatus having a charge removing means that can match the area where charges remain with the image area with high precision.

"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 are aligned with two sides forming a predetermined corner of the platen glass. 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 of the photoreceptor to the other end on the opposite side in a direction perpendicular to the direction of movement of the photoreceptor while maintaining a distance of (a) a first charge removing means that is movable in a direction perpendicular to the direction of movement of the photoreceptor; a second charge removing means capable of removing charges within a range that covers at least one end of the body and the end of the first charge removing means on the one end side; () a copy magnification input means for inputting a copy magnification; () an original size setting means;
() An area located on the other end side of the photoreceptor in the image area on the photoreceptor obtained by multiplying the original size given by the original size setting means and the copy magnification value input from the copy magnification input means. a calculation means for calculating the position of one side; and () when some of the light emitting elements of the first charge removal means are turned on based on the calculation result of the calculation means, the light emitting elements that are turned on and the light emitting elements that are turned off; unnecessary electrostatic latent image removal control means that controls the moving means so that the boundary between the two areas is located on one side of the area, and also controls the lighting of the first and second charge removal means; a detection section that moves integrally with the 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, and () for detecting the position of the detection section. When the sensor fixed to the main body of the copying machine and () the sensor detects the detection section prior to the control of the unnecessary electrostatic latent image removal control means, the sensor moves in a predetermined direction (direction B) until it no longer detects the detection section. By moving the first charge removing means, then moving the first charge removing means in the direction opposite to the above-mentioned predetermined direction (direction A), and again moving the first charge removing means by a predetermined amount from the detected point, or by removing unnecessary electrostatic charges. When the sensor is not detecting the detection section prior to the control of the image removal control means, the first charge removal means is moved in the opposite direction (direction A) and moved by the predetermined amount from the detected point. and (xi) input means for variably setting the predetermined amount used in the home position setting means.

"Operation" According to the present invention, the boundary between the light-emitting elements of the charge removing means that are lit and those that are off is always precisely located on a predetermined side of the image area. The remaining area will completely match the image area. Further, the home position of the charge removing means can be set by the rewriting means after the device is assembled.
Therefore, it is possible to match the two regions with high precision regardless of variations in the attachment of a sensor for detecting the home position.

"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 removal 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, they are said to be able to move freely in the direction of their rows.

For example, as shown by diagonal lines 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 capable of forming 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
Then, 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 in the direction of arrow C in FIG. 1 from the home position. Whether or not the photoreceptor 5 has reached the home position can be determined 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. Therefore, when the stepping motor 18 rotates forward or backward, the slide plate 1
6 as well as the second charge removing member 7 in the direction of arrow A or B.
It will move in the direction. 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 directed to the document detection sensor 34 in the Y direction.
When the light receiving element Y _o 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 in the ohm 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 axial direction of the photoreceptor 5 and the size of the copy paper are L ₁ mm, the size of the original 32 is L ₂ mm, and the second charge per one step (each rotation when one pulse is supplied) by the stepping motor 18. The amount of movement of the removing member 7 is Rmm, the pitch of the light emitting elements 8 of the second charge removing member 7 is Pmm, and the copying magnification is 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 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, when 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 find an integer N among the values obtained, and the remainder S at that time is used to move the second charge removing member 7 per step by the stepping motor 18. Find the value Q divided by the amount R.

(L ₂ ×M)/P=N...Remainder S, S/R=Q And in either case, based on the integer N, the Nth light emitting element 8 of the second charge removing member 7 from the left in FIG. The lights above will be turned off, and the others will be 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
By applying a pulse, the second charge removing member 7 is moved in the direction of arrow B by 40×0.25=10 mm. Even if the document is of a size other than the predetermined size, such as 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 member 7 is determined by how far it has moved in the direction of arrow B in FIG. 3 from the home position.
It can be expressed by the number of pulses applied to the stepping motor 18. Therefore, the data stored in the NVM 45 is data containing the number of pulses applied to the stepping motor 18.

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 removing 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 number of pulses 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. Such a situation may occur when copying an original of the same size as the previous original under the same copying conditions as the previous copy. If they are not the same, the CPU 41 then selects the position detection sensor 2.
1 is in the off state (step). Here, the position detection sensor 21 is in the off state, which means that the light shielding plate 2 is in the off state as shown in FIG.
0 is located to the left of the position detection sensor 21. On the other hand, if the position detection sensor 21 is on, it means that the light shielding plate 2
0 indicates that the position detection sensor 21 is shielded 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). Then, 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 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 light shielding plate 20
With this, the second charge removing member 7 is located at the home position.

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 it is not 0, the stepping motor 18 is further rotated in the normal direction by one step, and the counter is decreased by one (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, it is sufficient that the maximum amount of movement of the charge removing member 20 is approximately equivalent 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 the arrow A, the state shown in FIG. 11a is obtained. Here, when returning the charge removing member 20 to the home position, it is moved in the direction of arrow B, and the position detection sensor 21 is immediately turned off as shown in FIG. After that, as shown in FIG.
The right end 20 ₁ of 0 is the detection point 2 of the position detection sensor 21
_1. The charge removing member 20 is brought to rest at a position moved by a distance S from 1 in the direction of arrow A. The charge removing member 20 is now set at 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, when the charge removing member 20 moves from the state shown in FIG. 11a to the state shown in FIG. 11b or from this state to the state shown in FIG. Compare with. 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 the maximum allowable movement amount when returning the electricity removal member 20 to the home position. Move 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 the flowchart of FIG. 12, "timer set" refers to storing a numerical 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 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 indicating the occurrence of an abnormality is sent to the operator 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 the timer is subtracted by 1 while checking whether the position sensor is turned on (step). The ping motor is rotated forward by one step (step), and it is monitored whether the timer reaches zero in the same way as described above (step). If an abnormality occurs, the process moves to the step described above 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 removal 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. .

(Home Position) Returning to FIG. 11 again, the position detection sensor 21 is normally fastened and fixed to a frame (not shown) or the like using screws or the like. The home position of the charge removing member 20 is determined based on the detection point 21 ₁ of the position detection sensor 21 . The resolution of the position detection sensor 21 is approximately 0.1 mm. Therefore, if the position detection sensor 21 is not mounted with extremely high precision, the device will not be able to fully demonstrate its capabilities.

If this home position shifts to the right by, for example, 0.5 mm, charge removal at the corners of the image area may be insufficient, resulting in black linear shadows. For this reason, in this embodiment, the movement of the charge removing member 20 is set at 0.25 mm per step. Therefore, this level of precision is also required for mounting the position detection sensor.

However, it is impossible to accurately determine whether the position detection sensor 20 has been installed at the optimum position unless the copying is actually performed after the apparatus is assembled. This is this position detection sensor 2
This is because not only the accuracy of the assembly but also the mounting accuracy of the charge removing member 20, the stepping motor, and the mounting state of the frame that supports them are also related.

On the other hand, the task of readjusting the position of the position detection sensor based on the evaluation result becomes extremely complicated and takes a long time.

(Setting of Initial Value) Therefore, in the present invention, the initial value S shown in FIG. 11c can be set using, for example, a numeric keypad from the operation panel input section 46 (FIG. 9). A portion of this panel is illustrated in FIG. The set data is stored in the NVM 45.

In other words, at the device assembly stage, this NVM
The initial value is stored in the 45 as standard. For example, let the value be "3". In the adjustment process, press the diagnostic switch ₄₆₁ shown in FIG.
When a command is given to display the contents of the initial value of 5, "3" is displayed on the display ₄₆₂ . Here, copying is performed and the deviation of the home position of the charge removing member is inspected. Then, an initial value for correcting the deviation is selected. For example, let this value be “5”,
Input this using the numeric keypad ₄₆₃ . When the contents of NVM45 are rewritten in this way, the first
The initial value S shown in FIG. 1c is adjusted, and the charge removing member 20 is set at the optimal home position.

Of course, this adjustment can be made not only at the time of assembly but also during maintenance of the device by a service person. As a result, even if repairs such as replacing the charge removal member or position detection sensor are performed,
Adjustments can be made easily.

Note that the initial value for determining the home position may be rewritten using a digital switch, key, etc. provided within the copying machine instead of using the operation panel.

"Effects of the Invention" As explained above, according to the present invention, it is possible to always match the area where electric charge remains with the image area with high precision, thereby preventing copy paper from becoming inferior or missing images. , can make clean and accurate copies. 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. A partial plan view showing the positional relationship of the plates, Fig. 12 is a flowchart of the program showing the abnormality detection operation, Fig. 13 is a plan view of the main part of the rewriting means for rewriting the initial value that determines the home position, and Fig. 14 is the conventional FIG. 2 is a perspective view showing an example of an unnecessary charge removing device. 5...Photoreceptor, 6...Fixed charge removal member,
7...Movable charge removal member, 8...Light emitting element,
10... 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 ...Document detection sensor, 41...CPU, 43...ROM, 4
4, 45...RAM, 46...Operation panel input section, 47...Sensor input port, 48...Motor driver, 49...Light emitting element driver.

Claims (1)

[Claims] 1. Charge is uniformly applied to the surface of the photoconductor, and scanning exposure is performed with the two sides of the document aligned with the two sides forming the predetermined corners of the platen glass, and the document is exposed. 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, development is performed. In a copying machine that creates an image through each process of transfer and fixing, a plurality of light-emitting elements capable of selectively emitting light are placed at a predetermined distance from the surface of the photoreceptor and moved in the direction of movement of the photoreceptor. 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 a direction perpendicular to the direction of movement of the photoreceptor at least by the arrangement interval of these light emitting elements. a first charge removing means that is fixedly disposed at a predetermined distance from the surface of the photoreceptor, and a first charge removing means on one end of the photoreceptor in a direction orthogonal to the moving direction of the photoreceptor;
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; The first electric charge removing means is moved in a predetermined direction (direction B) until the electric charge is no longer detected, and then the first electric charge removing means is moved in the opposite direction to the predetermined direction (direction A), and the predetermined amount is detected again. or by moving the first charge removing means in the opposite direction (direction A) when the sensor is not detecting the detection section prior to controlling the unnecessary electrostatic latent image removing control means. home position setting means for positioning the first charge removal means at a home position by moving the first charge removal means by the predetermined amount from the point detected by the charge removal means; and input means for variably setting the predetermined amount used in the home position setting means. A copying apparatus comprising: