JPH11305523A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid erasing an image edge part not to be erased or leaving an image edge part to be erased by providing a means for calculating the erasing area on an image carrier corresponding to an erasing area, and an erase control means for lighting a light source corresponding to the calculated erasing area on the image carrier. SOLUTION: A CPU 24 calculates the erasing area on an image carrier corresponding to an erasing area designated by a designated calculation mode. It also performs an erase control for lighting a light source corresponding to the calculated erasing area on the image carrier. When a larger calculation mode is designated by a control panel 33 which is an erasing area designating means, the CPU 24 calculates the lighting area with the larger calculation mode, and determines this as the erasing area on the image carrier. When a smaller calculation mode is designated by the control board 33, the CPU 24 calculates the lighting area with the smaller calculation mode and determines this as the erasing area on the image carrier. According to this, setting of erasing area can be reasonably performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for exposing a charged image bearing member to form an electrostatic latent image on the image bearing member, and more particularly to partially removing a charged area of the image bearing member. The present invention relates to control of an eraser region of an eraser. This image forming apparatus can be used in, for example, a copying machine, a printer, and a facsimile (hereinafter, referred to as a copying machine).

[0002]

2. Description of the Related Art In a copying machine or the like, an electrostatic latent image is formed on an image carrier and developed with a developer to form a visible image. In this type of image forming, there is an image forming apparatus equipped with an eraser for erasing a charge or a latent image in an area unnecessary for image forming on an image carrier. The eraser has the effect of erasing the latent image outside the transfer paper, reducing wasteful consumption of toner, and the burden of cleaning for scraping off the toner remaining without being transferred.

This eraser can accommodate various sizes of transfer papers and originals by arranging a plurality of light sources (light emitting elements such as light emitting diodes) and switching the lighting pattern of the light sources according to timing.

Further, an arbitrary area on a document is designated, and the inside of the original is erased (inside erase) or the outside thereof is erased (outside erase). Conventionally, when an area to be erased is designated, when a rectangular area is designated, four-point coordinates are inputted based on the document edge. Then, the erase coordinates on the transfer paper (image carrier) are calculated from the inner erase area and the transfer paper area based on the original, an eraser lighting pattern is generated from the erase coordinates, and the light source of the eraser corresponding to the erase coordinates is turned on. And erase the latent image for that portion.

[0005]

From the erasing coordinates, a direction perpendicular to the rotation direction of the photosensitive member as an image carrier (hereinafter, Y direction)
The eraser lighting pattern is determined according to the coordinates of the eraser. However, since the exposure width of one unit light source of the eraser is wider than the pixel unit to be formed, the designated area width in the Y direction and the area actually erased are determined. A shift occurs in the width. If the width effective for exposure per light source, that is, the exposure width on the photoreceptor by one light source, is reduced, the deviation can be reduced, but the number of light sources and drivers for driving the light sources increases, There is a problem in cost.

In Japanese Patent Application Laid-Open No. Hei 5-204231,
An image forming apparatus has been proposed in which the erasing width of an image can be arbitrarily set by adjusting the light amount of the light source and changing the diffusion width of the light. However, the driver of the light source needs to output an arbitrary voltage value, and cost is increased. There is a concern that the problem will increase.

[0007] When the boundary (region edge) of the erasing region is, for example, in the middle of the exposure width of one light source, the erasing region width is set to be equal to the exposure width of one light source by turning on or off the light source. , Relatively shifted. That is, if the light source is turned on, Y
The width of the erasing area in the direction is extended by half the exposure width outside the erasing area, and becomes narrower by half the exposure width when the light is turned off.

In the conventional image forming apparatus, the eraser lighting pattern has been generated by either one of the methods. Therefore, an image edge that is not desired to be erased may disappear or an image edge that is desired to be erased may remain. In a mode in which the light source is turned off when the boundary of the erasure area is within the exposure width of one light source so that only the inside of the erasure area is erased, when the boundary of the erasure area (area end) is the edge of the original, Then, an image appears at the end of the erase area on the transfer paper. For example, when the area around the erasure area on the document is solid black, a black stripe appears.

SUMMARY OF THE INVENTION It is a first object of the present invention to rationally set a boundary of area erasure, and to prevent an image edge that is not desired to be erased from disappearing or an image edge that is desired to be erased remains. A second object of the present invention is to provide an image forming apparatus, wherein the light source is turned off when the boundary of the erasure area is within the exposure width of one light source. A third object is to prevent occurrence of an unintended image such as a streak.

[0010]

According to a first aspect of the present invention, there is provided an image carrier having a plurality of light sources arranged in a direction (Y) intersecting a moving direction of a charged image carrier. In an image forming apparatus provided with an eraser (11, 30 to 32) for removing charge, means (33, 331, 335) for specifying an arbitrary erasure area of a document, and calculation of an erasure area on an image carrier corresponding to an erasure area on the document. Mode
(Slightly larger / slightly smaller / slightly smaller with end correction) and means (335,39-341) to specify and the specified calculation mode
The erasure area on the image carrier corresponding to the designated erasure area (e
rY1num, erY2num), and erase control means (24) for turning on a light source corresponding to the calculated erasure area on the image carrier.

To facilitate understanding, reference numerals or corresponding items of the corresponding elements of the embodiment shown in the drawings and described later are added in parentheses for reference.

For example, the mode of calculating the erasure area is determined by setting the boundary of the calculated erasure area (referred to as a virtual erasure area) on the image carrier corresponding to the specified erasure area on the document to one light source. When the light source is located within the width of the illumination area, the light source is excluded from the group of light sources to be turned on for exposure (the lighting area is allocated to non-lighting). When the boundary of is located within the width of the illumination area of one light source, these calculation functions are used as a large calculation mode for calculating an illumination area that includes the light source in a light source group to be turned on for exposure. It is set in the erasure area calculation means (24), and when the large area calculation mode is designated by the erasure area designation means (33, 331, 335), the erasure area calculation means (2
4) calculates the illumination area in the large calculation mode, sets this as an erasure area on the image carrier, and uses the erasure area designation means (3
When the small calculation mode is designated in (3,331,335), the erasure area calculation means (24) calculates the illumination area in the small calculation mode and determines this as the erasure area on the image carrier.

According to this, by designating the small calculation mode, the edge of the image that is not desired to be erased does not disappear. When the large calculation mode is designated, the edge of the image to be erased does not remain. According to the image of the boundary of the erasure area set on the document, it is possible to select whether to leave or erase the image at the boundary, and the erasure area can be set rationally.

By the way, when the illumination area is calculated in the small calculation mode, when the boundary of the erasure area on the original is the edge of the original, the light source corresponding to the edge of the original is turned off. The boundaries of the power area should not be erased,
A streak corresponding to the original image may appear on the edge of the transfer paper. Therefore, in the later-described embodiment of the present invention, when calculating the illumination area in the small calculation mode, the erasure area calculation means may determine whether the end of the erasure area of the document corresponds to the document edge. The unit illumination area is extended in a direction corresponding to the outside of the document edge. As a result, the portion corresponding to the paper edge of the transfer paper is also neutralized, and no streak corresponding to the original image appears.

According to a second aspect of the present invention, there is provided a charged image carrier.
A plurality of light sources (1) arranged in the direction (Y)
An eraser (11, 30 to 3) having (1) for removing charge from the image carrier
In the image forming apparatus including (2), a unit (33,331,335) for designating an arbitrary erasure area of the document and a light source unit for exposing only the inside of the virtual erasure area on the image carrier corresponding to the designated erasure area When calculating the illumination area, when the end of the erasure area of the document is the document edge, the corresponding illumination area of the light source unit, the area calculation means (24) to expand in the direction corresponding to the outside of the document edge, And an erase control unit (24) for turning on a light source that irradiates light only to the calculated illumination area.

According to this, the edge of the image which is not desired to be erased does not disappear. When the end of the erasure area of the original is the end of the original, the erasure area calculating means widens the illumination area corresponding to the light source unit in the direction corresponding to the outside of the end of the original. , And no streak corresponding to the original image appears.

Other objects, other features and other aspects of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]

FIG. 1 shows an outline of a mechanism section of an embodiment of the present invention. This embodiment is an electrophotographic copying machine. In FIG. 1, a document placed on a contact glass 1 is pressed against the contact glass 1 by a pressure plate 1a having a white lower surface. An optical scanning system 2 including an exposure lamp and the like is provided below the contact glass 1. In this embodiment,
When the document feeder 23 is mounted and is closed (at a position where the document can be fed to the contact glass 1) and a document is placed thereon, the document feeder 23 is fixed. However, when the original is fed to the contact glass 1 and the copy of the original is completed, the original is discharged and the next original is fed to the contact glass 1. In the case of manual document placement, the operator opens the document supply device 23 upward and places the document on the contact glass 1.

An optical scanning system is mechanically driven to scan an original on the contact glass 1. An image formed by light reflected from the document is formed on the photosensitive surface of the photosensitive drum 3 via the optical scanning system 2. In FIG. 1, the photosensitive drum 3
Rotates clockwise.

The paper feed system has two stages, and the recording paper is fed out by a paper feed roller 6 or 7 from a paper feed tray 4 or a paper feed cassette 5 which is selected. The fed-out transfer paper is guided to the photosensitive drum 3 (feed) by passing between the registration roller 8 and the tip bending roller 9.

Around the photosensitive drum 3, a charger 10, an eraser 11, a developing unit 12, a pre-transfer charge removing lamp 13, a transfer unit 14, a separator 15, a separation claw 16, and a cleaning unit 17 are provided.
And a static elimination lamp 18 and the like.

Next, a schematic copy process will be described.
The copy process includes a start cycle, a copy cycle, and an end cycle.

When the print key is depressed by the operator, in the start cycle, the photosensitive surface of the photosensitive drum 3 is cleaned and neutralized by a grounded conductive brush and a cleaning blade provided in the cleaning device 17, and further a neutralization lamp 18 To eliminate the charge.
After the completion of cleaning and static elimination, the process exits the start cycle and becomes a copy cycle.

In the copy cycle, the photosensitive surface of the photosensitive drum 3 uniformly charged by the charger 10 is irradiated with the original reflected light on the contact glass 1 illuminated and scanned by the exposure lamp, and the surface potential of the original is reduced. It changes according to the intensity of the original reflected light. As a result, an electrostatic latent image is formed on the photosensitive drum 3. While passing through the developing device 12, the electrostatic latent image is visualized by attaching toner (hereinafter, referred to as a toner image).

The transfer paper fed to the registration roller 8 before the start of exposure is transferred to the registration roller 8 by the registration roller 8 at a predetermined timing corresponding to the rotation of the photosensitive drum 3.
The paper is fed toward. At this time, the leading edge of the transfer paper is slightly folded by the leading edge folding roller 9 in order to facilitate later separation.

When the transfer paper passes just above the transfer unit 14 to which a predetermined voltage is applied, the transfer paper comes into contact with the toner image formed on the photosensitive surface of the photosensitive drum 3 (transfer). Thereafter, the transfer paper is separated from the photosensitive surface of the photosensitive drum 3 by the separator 15 and the separation claw 16 and is sent to the transport belt 19. The transport belt 19 sends the transfer paper to the fixing device 20. The fixing device 20 is a roller having a built-in heater, where the toner image is fixed on the transfer paper, and is discharged to a copy tray 22 via a discharge roller 21.

After repeating the above-described copy cycle for the set number of sheets, the photosensitive drum 3 is further rotated about one turn to execute an end cycle for cleaning the photosensitive surface and removing static electricity. If there is a copy start instruction during the execution of the end cycle, the process skips the start cycle and proceeds to the copy cycle.

FIG. 2 shows a part of the electric control system of the copying machine shown in FIG. As shown in FIG. 3, on the operation panel 33,
Touch panel 335 also serving as display device, hard key 331
334, 338 and an indicator light. FIG.
The power pack 28 generates a high-voltage power supply such as a bias applied to the charging charger 10 and the developing device 12 around the drum and a bias applied to the transfer conveyance belt at the request of the CPU 24. The DF 23 is a document supply device placed on the contact glass 1. The DF can detect the size of the document, and can notify the CPU 24 of this. Reference numeral 30 denotes a shift register for registering erase data transmitted from the CPU 24 by serial communication. The erase data is read serially in synchronization with the clock signal from the CPU 24. Reference numeral 31 denotes a latch circuit which latches a parallel output (erase data) of the shift register 30 in response to a latch command from the CPU 24 and outputs the latched output to the driver 32.

The CPU 24 serially transmits all the erase data to the shift register 30, holds the erase data in the shift register, and causes the latch circuit 31 to hold the data. By this erase data output process, new erase data is output to the driver 32. The driver 32 turns on and off the LED 11 as the light source of the eraser 11. In addition, the CPU 24 controls an optical system such as a scanner and a paper transport system.

331 to 331 on the operation panel 33 shown in FIG.
34 and 338 are hard keys, and the touch panel 3
Reference numeral 35 denotes a two-dimensional display for both input and output. The ten keys 331 are used to input the number of copies and erasure coordinates.
Reference numeral 332 denotes an enter key for confirming the erasure coordinate input. Reference numeral 333 denotes a clear key for erasing the value input by the ten keys 331. A start key 334 is pressed after setting the number of copies and various modes to start copying.

The four keys displayed on the touch panel 335
Block 336 is a paper key. An arbitrary transfer paper (size) can be selected by touching this. A key block 337 is an inner erase key. By touching this, the mode shifts to the coordinate input mode for the area to be erased.
The initial setting key 338 is used to turn on an LED (light emitting diode) of the eraser 11 located on the calculated erasure coordinates in the direction Y perpendicular to the rotation direction of the photoreceptor in the erase mode according to the application and preference of the user. Control method (erasing area calculation mode)
This is also used when selecting (C).

FIG. 4 shows an outline of the sequence control (copy process control) executed by the CPU 24. When the power is turned on by turning on the power key, the CPU 24 clears the output port, initializes the RAM 26, etc., displays "Please wait!" On the message display, and lights the red lamp of the print key (steps 1 & 2).
2). Hereinafter, the word “step” is omitted in parentheses, and step No. Write only numbers. Next, the CPU 24
Reads the state of each part of the device and detects an abnormality. If there is an abnormality in the device, sets an abnormality display and activates a protection relay or the like (3 to 6). When the abnormality is eliminated and the process exits the preparation loop, the abnormality display is reset (7).

Next, as the initial conditions of the copy processing in the standard mode, the number of copies: 1, density: center, paper feed cassette: upper, and scaling ratio: 1 are set (8). Then, "Copy is possible" is displayed on the message display, the green lamp is turned on in place of the red lamp of the start key, and the copy ready state is set (9). Then, at "operation board reading" (10), the operator waits for an operator input.

Here, if there is a copy condition input, it is read and a process corresponding to the input (setting of copy conditions) is performed (P
RP).

When the start key is pressed, the CPU 24
"Start cycle" (13) and "1 copy processing"
(14) is executed, and the copy number counter (register) C
The content of the NC is incremented by one (15), and it is checked whether the number of copies CNC has reached the set number GN (standard set value 1 or the number set by the operator) (16). If not, "1 copy processing" (14) is executed. When the "1 copy process" (14) for the set number GN is executed, an end cycle is set (17), and the operation returns to "read operation board" (10).

FIG. 5 shows the above-mentioned "operation board reading" (1).
0) shows the contents of "other key reading process" (PRP) executed when a key other than the start key is operated. By this processing, the operator operates the touch panel 33
When the paper key 336 (one of the four) on the button 5 is pressed, the transfer paper is set (22). When the operator depresses the initial setting key 338, selection processing within the initial setting is performed (24). Here, a menu (not shown) is displayed.
When the inner erase key 337 is depressed, an inner erase area input process is performed (26), whereby the inner erase area input screen of FIG. 4 is displayed.

FIG. 6 shows "internal erasure area input processing" (26).
Indicates the contents of Here, the operator first selects X1 as the first input coordinate (31, 32). After that, it checks whether the numeric keypad is pressed, and if pressed, calculates the coordinate value to be updated after checking the number of input digits and reflects it on the display (33 to 3).
6). After that, the press of the enter key is checked.
uf is determined, and the input waiting coordinates (X1, X2, Y1, Y
2 is substituted for buf (37-4)
1). Thereafter, it is checked whether or not all the coordinates X1, X2, Y1, and Y2 have been input. If all of the coordinates have not been input, the non-input coordinates are set as the next input waiting coordinates (31), and buf is cleared (32). Then, in steps 33 to 41, the uninput coordinates are read.

When the input of all the coordinates X1, X2, Y1, Y2 is completed, the coordinates are corrected. In this case, when the coordinates exceed the size of the document permitted by the image forming apparatus, an allowable value is set to guarantee the magnitude relation of the coordinates. More specifically, the erasing mode is reset when Y1 = Y2, the values are replaced so that Y1 <Y2 when Y1> Y2, and Y1 = 3 when Y1> 300 mm.
00 mm, Y2> 300 mm if Y2> 300 mm
mm (300 mm is the maximum document width in the Y direction in the present image forming apparatus). After that, the area setting routine (26) ends. It checks whether the clear key 333 is pressed, and if pressed, initializes buf and reflects it on the display 42-44).

FIG. 9 is a diagram of the display device at the time of inputting coordinates for erasure. Only the display on the touch panel 335 is shown, excluding the hard key portion. Since the original is placed on the basis of the upper left corner of the contact glass, the area to be erased is designated at the four coordinates by ten keys 331 with the upper right of the original as the standard. First X
By inputting 1 and pressing an enter key 332, the process shifts to input of the next coordinate X2. Thereafter, the process proceeds to input of coordinates Y1 and Y2. When the numerical input of Y2 is completed, the selection screen of FIG. 10 is displayed.

FIG. 10 is a diagram of a display screen for setting the finish of the erased document in the vertical direction. The operator selects one of the key blocks 339, 340, 341 on the display screen. 339 is a slightly larger key for designating a larger calculation mode. By depressing this key 339, the inside erase area in the document Y direction becomes slightly larger. This is achieved by turning on the light source of the eraser located on the calculated erasure coordinates in the Y direction. The contents will be described later with reference to FIG.

Numeral 340 is a slightly smaller key for designating a smaller calculation mode. By depressing this key 340, the inside erase area in the Y direction of the document becomes slightly smaller. This is realized by turning off the light source of the eraser located on the calculated erasure coordinates in the Y direction. The contents will be described later with reference to FIG.

Reference numeral 341 denotes a key with a slightly smaller edge correction for designating a smaller edge correction calculation mode. By depressing this key 341, the inside erased area in the Y direction of the document becomes slightly smaller. This is realized by turning off the light source of the eraser located on the calculated erasure coordinates in the Y direction. However, if the edge of the original is specified in the Y direction when the erasure area is specified, the light source of the eraser located on the erasure coordinates is turned on. As a result, it is possible to prevent the occurrence of a single black line at the upper and lower ends of the inner erasure coordinates. The contents will be described later with reference to FIG.

342 is an end key. When the operator presses this button, the main selection screen (FIG. 10) is terminated,
The screen returns to the initial screen (FIG. 3).

FIG. 7 shows the "setting of internal erase erase pattern"("set at the beginning of" 1 copy process "(14) when CNC = 0 (the first copy of one original)). PD
T). FIG. 11 is a diagram showing the positional relationship between the eraser 11 and the transfer paper. With reference to FIG. 11, variables used in "setting of internal erase erase pattern" (PDT) will be described.

Since the original is placed on the basis of the upper left of the contact glass, the image on the upper end of the original is exposed to the lower end (front side) of the transfer paper on the drum. In FIG. 11, the light source number 0 side is the near side of the image forming apparatus, and the coordinates (Y value) follow from the near side.

DocY: document width (detected when a document is sent to the contact glass by the DF) erY1: erased coordinate Y1 (the initial value in the process of FIG. 7 is FIG. 6,
ErY2: Erase coordinate Y2 (In the process of FIG. 7, the initial value is
ImY1: Image coordinates Y1 (indicating transfer paper edge) imY2: Image coordinates Y2 (indicating transfer paper edge) erY1num: Erase coordinates Y1 Light source number (light source unit counted from light source number 0) ErY2num: Erase coordinate Y2 light source number (coordinate value of light source unit counted from light source number 0) imY1num: Image coordinate Y1 light source number (coordinate value of light source unit counted from light source number 0) imY2num: image coordinate Y2 light source Number (coordinate value of light source unit counted from light source number 0) ed: Length in Y direction of one light source (illumination width) EC: Distance from eraser end (exposure start end) of light source number 0 to center of transfer paper. In FIG. 11, the one with a white circle means the light source (LED) to be turned on. The light source LED of the eraser 11 with the light source number 0 or more and imY1num or less, erY1num or more and erY2num or less, imY2num or more and light source number n or less is turned on.

Referring to FIG. 7, first, when erasure coordinates Y2 exist outside the original, the CPU 24 corrects the erasure coordinates Y2 to match the original end. If the erasure coordinates Y1 are also outside the original, the erasure is not performed (51-54).

Next, when the erasure coordinate Y1 is 0 (document edge) and the "small edge correction calculation mode" is designated, it is regarded that the edge of the document has been designated as the inner erasure coordinate, and a flag is set. Otherwise, the flag is cleared (55-57).

Next, the erasure coordinate Y2 is larger than the document width,
If the "small calculation mode" is designated, it is assumed that the edge of the document has been designated as the inner erasure coordinates, and a flag is set.
Otherwise, the flag is cleared (58-60).

Next, in order for the center in the width direction of the transfer paper to pass a position separated by EC from the front end of the eraser (light source number 0), erasure coordinate correction is performed and image coordinates are set (61).

Next, from the image coordinates and the erasure coordinates, the order of the light source of the eraser to be turned on is determined (62). Here, the light source number is calculated with a floating point.

Next, the obtained light source number is rounded down (Y1) or rounded up (Y2) below the decimal point (6).
3).

Next, an erasing area (in units of light sources) according to a finishing mode of inner erasing determined by the designated calculation mode set in steps 55 to 60 and whether or not the erasing coordinates are the edge of the document. (64-7).
1). That is, in the "large calculation mode", erY1num
Is rounded down, and erY2num is rounded up to the decimal point to realize the large mode (64, 71).
That is, the light source located on the calculated erasure coordinates in the direction Y orthogonal to the rotation direction of the photoconductor is set to be turned on. In steps 65 and 68, it is determined whether or not the document ends need to be corrected for Y1 and Y2, and if correction is necessary, between erY1num and imY1num (transfer sheet end corresponding to the document end) or between erY2num and imY2num (document end). A light-off area, that is, a black stripe is prevented from appearing in the copy image at the corresponding transfer paper edge). That is, when the designated area coordinates in the direction Y orthogonal to the rotation direction of the photoconductor specify the document edge, the light source located on the calculated erasure coordinates is determined to be turned on. If no correction is needed, erY1nu
m is rounded up below the decimal point and erY2num is rounded down below the decimal point to make the erasure area smaller. That is, when the designated area coordinates in the direction Y orthogonal to the rotation direction of the photoconductor specify the edge of the document, the light source located on the calculated erasure coordinates is determined to be turned off (not lit). FIG. 8 shows the data transfer to the eraser and the latch timing. This process is performed in "1 copy process" (14 in FIG. 4). When the start key is pressed, the DF
Instructs the document 23 to convey the document to the contact glass, and when a signal indicating the document conveyance end arrives from the DF 23, rotates the photosensitive drum MT and starts driving the scanner. The document size information is received from the DF 23 at the same time as the document conveyance end signal, and the creation of the side erase pattern (side erase data) and the inside erase pattern (data) (FIG. 7) is performed. Do. After creating these erase patterns, the first erase data (full width erase data before the leading edge of the transfer paper: all lighting erase data) is serially transmitted to the shift register 30, and after the transmission is completed, the latch signal is latched. Transmit to the circuit 31. As a result, all the lighting data is given to the driver 32, and all the light emitting diode LEDs, which are the light sources of the eraser 11, are turned on (tip erase).

Thereafter, the sensor generates a timing signal (LE signal) indicating that the scanning of the scanner has reached the leading end of the document. In response to the LE signal, the CPU 24 serially outputs side erase data to the shift register 30. . Switching from the leading edge erase to the side erase occurs when the data of the shift register 30 is set (latched) in the latch 31.

After receiving the LE signal, the photosensitive drum 3
After waiting for rotation by LE2ERS (layout distance from the image exposure point by the scanner to the eraser 11), a latch signal is output to the latch circuit 31, and the LED of the eraser 11 outside the transfer paper area is turned on by side erase. . After that, the CPU 24 transmits the next erase data, that is, erase erase data, to the shift register 30. After receiving the LE signal, the CPU waits for the rotation of the drum 3 by LE2ERS + the erasure coordinate X1, and then applies a latch signal to the latch circuit 31 to light up with the inner erase data. The erase data is serially transferred to the shift register 30. After receiving the LE signal and waiting for the drum to rotate by LE2ERS + the erasure coordinate X2, the latch signal is applied to the latch circuit 31 to turn on the side erase data. After that, the next erase data, that is, all lighting erase data for the trailing edge erase, is serially transmitted to the shift register 30. Then, after the LE signal is equal to LE2ERS + Min (document length, transfer paper length), a latch signal is sent to the latch circuit 31, and full lighting (rear end erase) is performed. Min is the shorter value of the document length and the transfer paper length. Then the light source LE of erase 11
D is all turned off, and the rotation drive of the drum 3 is stopped. With such a control operation of the CPU 24, the inner erase by the eraser 11 is realized.

According to the embodiment described above, the user can select the large calculation mode, the small calculation mode, and the small end correction calculation mode, so that the user's purpose,
An image output that suits the user's taste can be obtained.

Considering the case where the light source on the image coordinates (coordinates used for turning on the light source for erasing the outside of the transfer paper in the Y direction and depending on the transfer paper size, imY1 and imY2 in FIG. 11) is not considered, the erasure is performed. As the area, the document edge in the Y direction (0
When coordinates larger than mm or the document width are input, when the document size cannot be detected, 0 mm and the maximum allowable coordinates are specified. Unlike the intention of erasing through the end of the transfer paper because the light source at that coordinate is erased, the result is that one black streak (corresponding to one light source) is generated at the top or bottom of the transfer paper and erased. There is a problem that remains without being. In the embodiment described above, since the light source is turned on only in such a case, the black streak does not occur.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a mechanism outline of an embodiment of the present invention.

FIG. 2 shows an example of an erasing device in the electric system of the copying machine shown in FIG.
FIG. 3 is a block diagram illustrating a portion related to the satellite control.

FIG. 3 is an enlarged plan view showing a part of an operation panel of the copying machine shown in FIG.

FIG. 4 is a flowchart showing an outline of a copy mechanism control operation of a CPU 24 shown in FIG. 2;

FIG. 5 is a flowchart showing the contents of a “reading process of another key” PRP shown in FIG. 4;

FIG. 6 is a flowchart showing the contents of an "inside erasure area input process" 26 shown in FIG.

FIG. 7 shows a CP in “1 copy processing” 14 shown in FIG.
"Setting of erase erase pattern" performed by U24 PD
This is a flowchart showing the contents of T.

FIG. 8 shows a CP in “1 copy processing” 14 shown in FIG.
This is a time chart showing the erase data transfer timing in the erase control performed by U24.

9 is an enlarged plan view showing a display on a touch panel 335 when an internal erasure area is set in the copying machine shown in FIG.

10 sets an internal erasure area in the copying machine shown in FIG. 1,
FIG. 14 is an enlarged plan view showing a display on the touch panel 335 when an area calculation mode is designated.

11 is a plan view showing an arrangement of light sources of an eraser 11 of the copying machine shown in FIG. 1 and a positional relationship between transfer sheets.

[Explanation of symbols]

 1: Contact glass 2: Optical scanning system 3: Photoreceptor drum 4: Manual paper feed tray 5: Paper feed cassette 6, 7: Paper feed roller 8: Registration roller 9: Tip bending roller 10: Charger 11 : Eraser 12: developing device 13: static elimination lamp before transfer 14: transfer device 15: separator 16: separation claw 17: cleaning device 18: static elimination lamp 19: transport belt 20: fixing device 21: discharge roller A 22: Copy tray 23: Document feeder

Claims (4)

[Claims] 1. An image forming apparatus having a plurality of light sources arranged in a direction intersecting with a moving direction of a charged image carrier and having an eraser for eliminating charge of the image carrier, an arbitrary erasing area of a document is designated. Means for designating a mode for calculating an erasure area on an image carrier corresponding to an erasure area on a document; and a designated calculation mode on an image carrier corresponding to a designated erasure area. Means for calculating an erasure area;
An erase control unit for turning on a light source corresponding to the calculated erasure area on the image carrier. 2. The erasure area calculation means for exposing all virtual erasure areas on an image carrier corresponding to a specified erasure area on a document when a large calculation mode is designated. An illumination area is calculated for each light source, and when the small calculation mode is designated, an illumination area for each light source for exposing only the inside of the virtual erasure area is calculated, and the erase control means calculates the illumination area. The image forming apparatus according to claim 1, wherein a light source that emits light only to an illumination area is turned on. 3. The erasing area calculating means, if the end of the erasing area of the original is the original end when the small calculation mode is designated, the illuminating area corresponding to the light source unit is set to the original end. The image forming apparatus according to claim 2, wherein the image forming apparatus extends in a direction corresponding to the outside of the image forming apparatus. 4. An image forming apparatus having a plurality of light sources arranged in a direction intersecting with a moving direction of a charged image carrier and having an eraser for removing charge of the image carrier, an arbitrary erasing area of a document is designated. Means, calculating an illumination area for each light source for exposing only the inside of the virtual erasure area on the image carrier corresponding to the designated erasure area, and when the end of the erasure area of the original becomes the original end, A region calculation unit for expanding a corresponding light source unit illumination region in a direction corresponding to the outside of the document edge, and an erase control unit for turning on a light source that emits light only to the calculated illumination region are provided. An image forming apparatus comprising: