JPS63236057A - Image forming device - Google Patents

Abstract

PURPOSE:To simply bring a part of one original to an image formation by the polarity being different from other part, by providing a control means forming an image corresponding to an erased original image on a material to be transferred, by the polarity being opposite to an image carrying body. CONSTITUTION:A prescribed range changing the polarity in the original is instructed by a spot light, an image corresponding to an original image erased from the image of the inside of a range instructed by this spot light is formed on a material to be transferred, by a developer of one electrification polarity of a developing means (developing sleeve) by the same polarity as an image carrying body (photosensitive drum) 10 with respect to the transfer voltage of a transfer means (transfer electrifier) 18, and also, an image corresponding to an original image erased from the image of the outside of the range instructed by the spot light is formed on the material to be transferred, by the developer of the other electrification polarity of the developing means by the opposite polarity to the image carrying body with respect to the transfer voltage of the transfer means. In such a way, a part of one original can be brought to the image formation simply by the polarity being different from other part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus applied to, for example, an electronic copying machine.

(Prior Art) As is well known, copying machines have the function of copying original images as they are onto paper, or of enlarging or reducing original images. (masking), or (trimming) which erases and copies images outside of a specified range.
has been developed and put into practical use.

By the way, with such a device, part of the manuscript (partial)
It was not possible to change the polarity of the

In other words, it was not possible to partially convert a positive image into a negative image, or to convert a negative image into a positive image.

For this reason, when creating drawings, designs, etc., all drawings are positive and only the necessary parts are reversed, and when creating posters, flyers, etc., it is necessary to ■black out the necessary parts, or ■copy the necessary parts onto an OHP sheet, etc. and use photographic paper. If you have a copying machine capable of full-face reversal development, make a full-face negative copy from the positive original, cut out the necessary parts, and then process it as an original. One possibility is to use it by pasting it on the original.

However, in the case (2), since the area is large relative to the pattern portion, there is a drawback that it takes time and effort. ■、■
In this case, the disadvantage is that there are many steps and it is troublesome.

(Problems to be Solved by the Invention) As mentioned above, this method eliminates the drawback that it is not possible to easily form an image on a part of one original with a polarity different from that on other parts. It is an object of the present invention to provide an image forming apparatus that can easily form an image with a portion having a polarity different from that of the other portion, and can easily specify the range in which the polarity is to be changed.

[Structure of the Invention] (Means for Solving the Problems) The image forming apparatus of the present invention includes a scanning means for optically scanning a document placed on a document table, and an optical image obtained by the scanning means. an optical system that forms an image on a charged image carrier, a developing device that develops the image formed on the image carrier, and a transfer device that transfers the developed image to a transfer material. wherein the developing means uses a one-component magnetic developer having a mixture of both charge polarities, and an indicating means provided in the scanning means for indicating a predetermined range in which the polarity of the document is to be changed; an erasing means for erasing from the image carrier an image outside the range indicated by the spotlight by the means, or an image inside the range indicated by the spotlight, from the image carrier, and a range indicated by the spotlight by the indicating means; An image corresponding to the original image erased by the erasing means from the inside image of the image is transferred to the transfer material using a developer having the same polarity as the transfer voltage of the transfer means and the charge polarity of one of the developing means. The transferred material is conveyed again to the transfer means, and an image corresponding to the original image erased by the erasing means is removed from the image outside the range indicated by the spot light by the transfer means. The image forming apparatus includes a control means for applying a transfer voltage to the transfer material using a developer having a polarity opposite to that of the image carrier and the other charged polarity of the developing means.

(Operation) This invention specifies a predetermined range in which the polarity of a document is to be changed using a spot light, and transfers an image corresponding to the erased document image from an image inside the range designated by the spotlight to a transfer voltage of a transfer means. is formed on the transfer material using a developer having the same polarity as the image carrier and the charged polarity of one of the viewing means, and an image corresponding to the original image is erased from the image outside the range indicated by the spot light. The transfer voltage of the transfer means is applied to the transferred material using a developer having a polarity opposite to that of the image carrier and the other side of the developing means.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 2 and 3 schematically show an image forming apparatus of the present invention, such as a copying machine. That is, 1 is a main body of a copying machine, and a document table (transparent glass) 2 is fixed to the upper surface of the main body 1 to support a document. Fixed scales 21 and 22 are provided at both ends of the document table 2 to serve as a reference for setting the document, and furthermore, a document cover 11 and a work table 12 which can be opened and closed are provided near the document table 2.

The original placed on the original platen 2 is moved back and forth by an optical system consisting of an exposure lamp 4 and mirrors 5, 6, and 7 along the lower surface of the original platen 2 in the direction of arrow a. It is designed to be exposed and scanned. In this case, mirror 6.7 moves at half the speed of mirror 5 so as to maintain the optical exposure length. The light reflected from the original by the scanning of the optical system, that is, the light reflected from the original by the light irradiation of the exposure lamp 4 is reflected by the mirror 5.6.7, passes through the variable magnification lens block 8, and further passes through the mirror 91. .92
．． The image of the document is reflected by the photoreceptor drum 10 and guided to the photoreceptor drum 10 composed of a selenium drum.
The image is formed on the surface of the

The photosensitive drum 10 rotates in the direction of arrow C in the figure, and the surface is first charged (+700 volts) by the charging device 11, and then the image is exposed to slit light to form an electrostatic latent image on the surface. be done. This electrostatic latent image is created by a developing device 12 containing a single-component magnetic developer containing a mixture of positive (charged) polarity toner and negative (charged) polarity toner, that is, a mixture of polarity. Once attached, it can be visualized.

On the other hand, the paper (transferring material) P is delivered from the selected upper paper feed cassette 131, middle paper feed cassette 132, or lower paper feed cassette 133 to the feed rollers 141, 142, 14.
3 and roller pairs 151, 152, and 153, and are guided through a paper guide path 161, 162, and 163 to a pair of registration rollers 17, and guided to a transfer section by this pair of registration rollers 17. It has become. Here, the above paper feed cassette 131.132.13
3 is removably provided at the lower right end of the main body 1, and either one can be selected on the operation panel described later. Note that each of the paper feed cassettes 131.
132.13:I are those whose cassette sizes are detected by cassette size detection switches 601, 602, and 603, respectively. The cassette size detection switches 601, 602, and 603 are composed of a plurality of microswitches that are turned on and off according to the insertion of cassettes of different sizes.

The paper P sent to the transfer section comes into close contact with the surface of the photoreceptor drum 10 at the transfer charger 18, so that the toner image on the photoreceptor drum 10 is transferred by the action of the charger 18. . A DC voltage (transfer voltage) of +4.5 volts (during normal development) or -4.3 volts (during reverse development) is applied to the transfer charger 18 by a power supply circuit to be described later. It has become so.

-〇- The transferred paper P is electrostatically peeled off from the photoreceptor drum 10 by the action of the peeling charger 19 and placed on the conveyor belt 20.
The transferred image is conveyed by a fixing roller 21, which serves as a fixing device, provided at the end thereof, and the transferred image is fixed by passing therethrough. The sheet P after fixing is sent to a tray 25 outside the main body 1 by a pair of sending rollers 22, a sorting gate 23 operated as shown by the solid line, and a pair of paper ejecting rollers 24. In addition, the photosensitive drum 1 after transfer
0, the residual toner on the surface is removed by the cleaner 26, and the residual image is erased by the static elimination lamp 27, so that the initial state is restored. Note that 29 is a cooling fan for preventing the temperature inside the main body 1 from rising.

On the other hand, a multiple copying unit 28 is provided below the copying machine main body 1 to make it possible to copy both sides of a sheet of paper or to make multiple copies on the same side. - This unit 28 includes a gate 23 for the above-mentioned sorting, and a pair of paper ejection rollers 2.
4, the sorting is performed by a plurality of roller pairs 28b that guide the sheets taken in by the gate 23 to the stacking section 28a.
, 28c.

28d is provided. Further, the stacking section 28a is provided with a delivery roller 28e that sends out the paper temporarily stored in the stacking section 28a. This delivery roller 28e can move up and down as shown by the arrow in the figure, depending on the thickness (number of sheets) of the stored paper. The paper sent out by the delivery roller 28e is guided to the control gate 28q via a separation roller pair 28f that separates the paper sheets one by one and sends them out. When performing multiple copying, this control gate 28a is rotated in the direction of the arrow M shown in the figure, and the paper is transported by the pair of conveying rollers 28h,
The paper is guided to the registration roller pair 17 via the paper guide path 28i.

Further, when double-sided copying is to be performed, the state shown in the figure is used, and the paper is guided to the reversing section 28 via a pair of conveying rollers 28j. When the paper is stored in the reversing section 28k, the control gate 28g is rotated in the direction of arrow T in the figure, and the paper sent by the pair of transport rollers 28j is transferred to the pair of transport rollers 28h,
The paper is guided to the registration roller pair 17 via the paper guide path 2B+. In this example,
The control gate 28q is always rotated in the direction of the arrow M shown in the figure, and only multiple copying is possible.

FIG. 4 shows the operation panel 30 provided on the main body 1. 301 is a copy key for instructing the start of copying; 302
is a display section consisting of, for example, a liquid crystal dot matrix display, and display information stored in a memory 140, which will be described later, is switched and displayed in accordance with each mode. Around this display section are selection keys 31a, 31b, 31C131d1 for selecting the mode displayed on this display section 302.
31e, 31f, 31a131h are provided.

Further, the operation panel 30 includes operation keys 30a, 30b, 30c, and 30d for moving a spot light source indicating an original erase position and a gradation change position, which will be described later, and a position designation key for inputting a coordinate position indicated by the spot light source. 30e is provided.

As shown in FIGS. 5(a) and 5(b), the display unit 302 displays the status of the device, etc., and displays trimming, masking mode, image movement mode, etc. as shown in FIG. 5(C). , edge erase mode, multiple copy mode, two-page original copy mode, partial inversion (positive-negative, negative-to-positive conversion) mode, multiple copy mode, and centering mode selection screen can be displayed graphically, As shown in Figures (CI) to (Q), the edge mode selection screen for selecting one or two originals, the setting screen for the number of copies, the copy magnification selection screen, and the copy status screen are now graphically displayed. It has become.

FIG. 6 shows a drive mechanism for reciprocating the optical system. That is, the mirror 5 and the exposure lamp 4 are supported by a first carriage 411, and the mirror 6.7 is supported by a second carriage 412, respectively, and these carriages 411, 412 are guided by guide rails 421, 422 in the direction of arrow a. It can be moved in parallel. That is, the four-phase pulse motor 33 drives the pulley 43. An endless belt 45 is stretched between the pulley 43 and the idle pulley 44, and one end of a first carriage 411 that supports the mirror 5 is fixed to a midway portion of the belt 45. On the other hand, a second carriage 422 supporting the mirror 6.7
The guide portion 46 includes two grooves spaced apart in the axial direction of the rail 422.
Two pulleys 47.47 are rotatably provided, and a wire 48 is stretched between these pulleys 47.47. One end of this wire 48 is fixed to a fixed part 49, and the other end is fixed to the fixed part 49 via a coil spring 50. Further, one end of a first carriage 411 is fixed to a midway portion of the wire 48. therefore,
As the pulse motor 33 rotates, the belt 45 rotates, the first carriage 411 moves, and the second carriage 422 also moves accordingly. At this time, since the pulleys 47, 47 serve as movable pulleys, the second carriage 422 moves in the same direction as the first carriage 411 at 1/2 the speed. In addition, the first and second carriages 4
The moving direction of 11.412 is controlled by switching the rotation direction of the pulse motor 33.

Further, the first carriage 411 is moved to a predetermined position (home position according to the magnification) by driving the motor 33 according to the paper size and magnification. Then, when the copy key 301 is pressed, the first
The carriage 411 is first moved toward the second carriage 412, and then the lamp 4 is turned on and moved away from the second carriage 412. When scanning of the original is completed, the lamp 4 is turned off and the first carriage 411
is returned to the home position.

FIG. 22 shows the structure of the developing device 12.

That is, the non-magnetic sleeve 170 as a developing sleeve
, a fixed magnetic pole 171 included in this developing sleeve,
and a blade 172 that regulates the amount of developer conveyed.

The developing sleeve 170 is supplied with +200 volts as a developing bias voltage during normal development or +400 volts as a developing bias voltage during reversed image processing by a power supply circuit to be described later.
A DC voltage of volts is selectively applied.

The toner used in the developing device 12 has an average particle size of 1
A negatively charged toner (negative polarity toner m; toner with opposite polarity to the photoreceptor drum 10) using a styrene-acrylic resin with an average particle size of 10 μm as the main resin, and a positive toner using a styrene-acrylic resin with an average particle size of 10 μm. A chargeable toner (positive polarity toner; toner having the same polarity as the photoreceptor drum 10) is used.

Therefore, the case where development is performed on a positive image of the original will be explained using FIGS. 23(a) and 23(b). In other words, when performing regular positive development,
The photosensitive drum 10 is positively charged with +700V, and the developing bias voltage is +200V and the transfer voltage is +4.
．． 5 KV and use the negatively charged toner θ of the developing device 12 (see figure (a)). When performing positive negative reversal development, the photosensitive drum 10 is positively charged with +700 V, and the developing bias is Voltage +400V,
The transfer voltage is set to -4.3 KV, and development is carried out using positively charged toner O of the developing device 122 (see FIG. 12(b)).

FIG. 7 shows the overall control circuit.

The main control unit 71 includes an operation panel 30 and various switches and sensors, such as the cassette size detection switch 601.
, 602, 603, etc., and applies a voltage to the charging device 11.
6a1 a power supply circuit 76b for applying a bias voltage to the developing sleeve 170 in the developing device 12; and the transfer charger 1;
8, the power supply circuit 76C1 applies voltage to the static elimination lamp 2;
f'a, the heater 23a of the pair of fixing rollers 23, the exposure lamp 4, the motor 33, etc., to perform the above-described copying operation, as well as the spot light m131, the pulse motor 33, 135, the memory 1401 and the erase array 15.
0, the array driving section 160 and the like are controlled to perform an operation of erasing unnecessary portions of the document. Note that the spot light source 131, pulse motor 135, erasing array 1501, array drive section 1601, and memory 140 will be described later.

Further, the main control section 71 displays characters and patterns on the display section 302 for each mode in accordance with character information or pattern information stored in a memory (not shown). A quick disk or the like may be used as the memory.

The exposure lamp 4 is controlled by the main control section 71 via the lamp regulator 81, and the heater 23a is controlled by the heater control section 8.
The motor 33.13 is controlled by the main control unit 71 via the motor 33.
5 is controlled by the main control section 71 via a motor driver 78.

The power supply circuit 76a is controlled by a main control section 71, and the main control section 71 causes the charger 11 to be charged at +700.
By applying a voltage, the photosensitive drum 10 is positively charged.

Further, the power supply circuit 76b is controlled by the main control section 71 via the switching circuit 141a, and performs voltage switching control according to the normal development signal and the reverse development signal from the main control section 71. +200 volts is applied to the sleeve 170 as a developing bias voltage during normal development, and +400 volts is applied as a developing bias voltage during reversal development.

Further, the power supply circuit 76c is controlled by the main control section 71 via the switching circuit 141b, and performs voltage and polarity switching control according to the normal development signal and the reverse development signal from the main control section 71. +4.5 volts are applied to the transfer charger 18 as a transfer voltage during normal development, and -4.3 volts are applied as a transfer voltage during reversal development.

Next, the document image erasing means will be explained.

In FIGS. 8 and 9, a guide shaft 130 is provided in the first carriage 411 along the lamp 4 in a part where the light of the lamp 4 is blocked, and this guide shaft 130 has a guide shaft 130 that is used to mark the erasing range of the original. Spot light source 131 as a means of giving instructions
is movable. This spot light source 131
A light-emitting element 132, such as a light-emitting diode or a lamp, and a lens 1 are provided facing the document table 2.
33, and the light generated by the light emitting element 132 is irradiated by the lens 133 onto the document table 2 as a spot light having a diameter d.

In addition, the spot light 111131 is emitted from a timing belt (toothed belt) 134 disposed along the guide shaft 130.
is connected to. This timing belt 134 is passed between a pulley 136 provided on the rotating shaft of a pulse motor 135 and a driven pulley 137. Therefore, by rotating the pulse motor 135, the spot light source 131 is moved in a direction perpendicular to the scanning direction of the first carriage 411. In addition, a spot light il! A position sensor 138 consisting of a microswitch is provided to detect the initial position of 131. For example, when the spot light source 131 is moved, the spot light source 131 first comes into contact with the position sensor 138 and its initial position is detected.

Next, a method of specifying the erasing range of the document using the spot light 1131 will be explained using FIGS. 10 to 12. When specifying the erasing range of a document, the document G is set with the copy side facing down on the fixed scale 2 side, as shown in FIG.

In this state, when the operation keys 30a to 30d are operated, the spot light source 131 is moved with the light emitting element 132 turned on. That is, when the operation keys 3Qt) and 30d are pressed, the motor 33 is driven and the first carriage 411
Then, the spot light source 131 is moved in the scanning direction (direction of arrow X shown in FIG. 10). In addition, operation keys 30a, 3
When 0c is pressed, the motor 135 is driven and the spot light source 131 is moved in a direction perpendicular to the scanning direction (direction of arrow X shown in FIG. 10).

When specifying the partial reversal mode, the operator operates the operation keys 308 to 30d while visually observing the spot light that has passed through the original G, and moves the spotlight to point S1 on the original G shown in FIG. 11, for example. Press the position designation key 30e. Then, the coordinate position specified by this S1 point is stored in the main control section 71 shown in FIG. Similarly, when the position designation key 30e is pressed with the spotlight moved to 82 points on the document G, the positions of the 82 points are stored in the main control section 71. The position of this spot light can be detected, for example, by counting the number of drive pulses of the pulse motor 33.135. After this, as shown in FIG.
A rectangular area with one point as a diagonal point is designated as an erasing range for regular development (reference image polarity) as one (image) polarity.

In addition, in the frame W formed by the 81 points and 82 points, the area other than the rectangular area whose diagonal points are the Sl-' point and the S2-' point of the inner edge Wa is the erasing range for reversal development as the polarity. is specified as

In this way, when the erasing range is specified, the main control unit 7
1, and the memory 140 stores a high level signal 11111 in the erase range area and a low level signal IIO11 in the other areas. That is, this memory 140 is constituted by, for example, a RAM whose capacity in each column direction is approximately equal to the movement distance of the spotlight 1i3i in the X direction divided by the position resolution in the yX direction, and according to the data supplied from the main control section 71, In the case of one image polarity (reference image polarity), as shown in FIG. 12(a),
In the case of the other image polarity, as shown in FIG. 12(b), a high level signal is stored in the address corresponding to the shaded area, and a low level signal is stored in the other addresses.

The document G for which the erasure range has been specified as described above is
It is reversed in the X direction shown in FIG. 10, and set on the fixed scale 21 side, with the copy side facing down, and copied. Therefore, in this state, the original image and the erased data stored in the memory 140 are associated with each other.

On the other hand, as shown in FIG. 13, an erasing array 150 as erasing means is provided close to the photosensitive drum 10, for example, between the charger 11 and the exposure section Ph. As shown in FIGS. 14 and 15, this erasing array 150 has a plurality of light shielding cells 151 arranged in a direction perpendicular to the rotational direction of the photoreceptor drum 10, and each light shielding cell 151 has a plurality of light shielding cells 151 arranged therein. A light emitting element 152 made of, for example, a light emitting diode as shown in FIGS. 16(a) and 16(b) is provided. Furthermore, a lens 153 is provided in the opening of each cell 151 facing the photoreceptor drum 10 to focus the light from the light emitting element 152 onto the surface of the photoreceptor drum 10 . The number of light emitting elements arranged in this erasing array 150 matches, for example, the capacity of the memory 140 in the column direction. here,
Assuming that the width of each light emitting element 152 is P and the number of light emitting elements 152 is N, the total length of the erasing array 150 is Q=NXP.

The erase array 150 is driven by the array driver 160 described above. As shown in FIG. 17, this array driving section 160 includes a shift register 161 having the same number of bits as the number of bits in the column direction of the memory 140, and a store register 1 in which the contents of this shift register 161 are held.
62, it is constituted by a switch circuit 164 consisting of a plurality of switch elements 163 that are controlled on and off by each output signal of this store register 162, the movable contacts 163a of these switch elements 163 are grounded, and the fixed contacts 163b are grounded. Each of the light emitting elements 152 constituting the erasing array 150 is connected to each cathode. The anode of each of these light emitting elements 152 is connected to the power supply VCC through a current limiting resistor R, respectively.

After specifying the erase range of the original as described above, when the original cover 11 is closed and the copy key 301 is pressed, the first carriage 411 and the photosensitive drum 10 are operated, and the memory 140 is read in the row direction. Data for one column (as shown in FIG. 12) is sequentially read out. This read data D1 is transferred to the shift register 161 of the array driving section 160 in response to the clock signal CLK.

After one column of data is transferred to the shift register 161, the charged portion of the photoreceptor drum 10 is transferred to the erase array 15.
When the value reaches 0, the main control unit 71 outputs the latch signal LTH, and the data stored in the shift register 161 is supplied to the store register 162 in response to this signal. That is,
Since the erasing array 150 is arranged between the charger 11 and the exposure section Ph, one column of data output from the memory 140 is, for example, arranged between the erasing array 150 and the exposure section Ph.
Assuming that the angle of h is θ1 and the photosensitive drum 10 is rotating at each speed, the output timing of the latch signal LTH is controlled so that it is supplied to the store register 162 before θ1/ω.

Each switch element 163 of the switch circuit 164 is controlled by the output signal of the store register 162. That is, when the output level of the store register 162 is high level, it is turned on, and when it is low level, it is turned off. As a result, the light emitting elements 152 connected to each switch element 163 are turned on when the switch element 163 is on, and are turned off when the switch element 163 is off. Therefore, among the charged portions of the photoreceptor drum 10, the portion where the light emitting element 152 is illuminated by -26 is neutralized, and even if this neutralized portion is subsequently exposed to light, no electrostatic latent image is formed, and no electrostatic latent image is formed on the portion of the original image. This means that deletion has occurred. Thereafter, in the same manner, the memory 14
Data of 0 is read out one column at a time, and the image is erased.

Next, the copying operation of the present invention in the above configuration will be explained with reference to the flowchart shown in FIG. For example, in the mode designation state shown in FIG. 5(C) (ST1), the operator selects the partial inversion (polarity change) mode by pressing the selection key 31b (ST2). Then, a selection screen for reversing the image polarity change is displayed for the selection key 31a, as shown in FIG. 18(a), and a pattern of the document frame and the specified range (pattern frame) is displayed (ST3). . At this time, partial inversion (polarity conversion; positive→negative) display is performed by displaying only the polarity (positive) portion of the basic image.

Next, the operator turns over the document G on which the image shown in FIG. 19 is written and places it on the document table 2 (ST6). Next, the operator presses the operation keys 308 to 30d.
and position designation key 30e to designate 81 points and 82 points as the polarity change range on the document G (ST
7). Then, the inner edge Wa and the outer edge Wb1 of the frame W in the range specified by the spotlight w131, that is, 51
- the positions of two points, one point and 82″ point, and one point Sl,
The control unit 71 performs calculations based on the positions of the two points, one point S2, and the memory 140 stores the spots as erase data for the inversion image (negative) portion, as shown in FIG. 12(a). A high level signal is stored in an address corresponding to the inside from the outer edge wb of the frame W caused by the light 1131, a low level signal is stored in an address corresponding to the outside from the outer edge wb of the frame W caused by the spot light source 131, and normal development (positive) is performed. As part of the erased data, as shown in FIG. 12(b), the inner edge Wa of the frame W caused by the spot light source 131 is
A high level signal is stored at an address corresponding to the outside from , and a low level signal is stored at an address corresponding to the inside from the inner edge Wa of the frame W formed by the spotlight 81131 (
ST8).

In this state, when the copy key 301 is turned on, a copying operation is performed on the portion of the document G other than the polarity changed portion using the developing device 12 containing negative polarity toner and positive polarity toner and the erasing array 150.

That is, the first carriage 411 is moved and the document G is moved.
<5T9).

Along with this, the array drive section 160 includes the memory 140.
12(a) is supplied, and the erasing array 150 is operated according to this erasing data, so that the charges on the inside of the outer edge wb of the frame W are removed from the surface of the photoreceptor drum 10. It is erased (ST10). Also, at this time, the switching circuit 14 receives the regular development signal from the main control section 71.
1a.

By controlling 141b, the transfer charger 1
At the same time, a voltage of +4.5 is applied to the developing sleeve 170 as a developing bias voltage during normal development.
Apply 200 volts (ST10-).

Therefore, a positive image having the same polarity as the image polarity of the original is formed on the surface of the photoreceptor drum 10 only in a portion other than the area surrounded by the outer edge Wb of the spot light W of the original G using negative polarity toner. In synchronization with this operation, the paper P is supplied to the transfer section by the pair of registration rollers 17, and the image outside the range surrounded by the outer edge wb of the frame W is transferred onto the paper P. As a result, when the above-mentioned image is developed and transferred, the paper P has the following image as shown in FIG.
A positive image having the same image polarity as the original is copied only in a portion of the original G other than the area surrounded by the outer edge Wb of the frame W.

Thereafter, the copied paper P is again conveyed to the transfer section by the multiple copying unit 28 described above (ST11
). Next, a copying operation of the polarity-changed portion of the original G is performed using the developing device 12 containing positive polarity toner and negative polarity toner and the erasing array 150. That is, the first carriage 411 is moved and exposure scanning of the original G is performed (ST12).

Along with this, the array drive section 160 includes the memory 140.
The erase data of the positive portion shown in FIG. 12(b) is supplied, and the erase array 150 is
is operated, and the charges on the outside of the inner edge Wa of the frame W are erased from the photosensitive drum 10 (ST13). At this time, the switching circuit 141a1141b is controlled by the reverse development signal from the main control section 71, thereby applying voltages -4 and 3 to the transfer charger 18, and applying reverse development to the developing sleeve 170. Apply +400 volts as the developing bias voltage (ST13M).

Therefore, on the surface of the photoreceptor drum 10, a negative image whose polarity is opposite to the image polarity of the original is formed in the area surrounded by the inner edge Wa of the spot light W of the original G using positive polarity toner. In synchronization with this operation, the paper P conveyed to the transfer section by the multiple copying unit 28 is supplied, and the image in the area surrounded by the inner edge Wa of the frame W is transferred onto the paper P. As a result, as shown in FIG. 21, on this paper P, a positive image having the same polarity as the original is formed on the portion of the original G other than the area surrounded by the outer edge wb of the frame W, and a positive image is formed on the inner edge of the frame W. A negative image is formed in which the image polarity is reversed (reversed) in the area surrounded by Wa. Then, the paper P is sent to the paper ejection tray 25 via the paper ejection roller 24 (ST14
).

As a result, it is possible to perform image formation on a part of one positive document with negative image polarity and on the other part with positive image polarity. Furthermore, when the image polarity is changed, the positive image and negative image do not overlap, and are clearly copied.

In addition, in response to the display in step 3, the operator selects inversion (making part of the original positive instead of making part of the original negative) by pressing the selection key 31a ( ST4). Then, as shown in FIG. 18(b), the display unit 302 performs a partially inverted display by displaying the inside of the pattern frame (ST5).
. Thereafter, by carrying out the operations from step 6 to step 14, it is possible to form an image on only a portion of one positive document with positive image polarity and on the other portion with negative image polarity.

As mentioned above, when changing the image polarity of a part of the document,
In other words, when copying a predetermined 0 part of one original with negative image polarity and copying other parts with positive image polarity, a one-component magnetic developer with both polarities and a mixture of charging polarities is used. By setting the transfer voltage polarity to the same polarity as the photoconductor drum during regular development and the opposite polarity to the photoconductor drum during reversal development, the inside of the indicated range is erased and negatively charged the first time. I made a copy using polar toner, and the second time I erased the outside of the specified range and copied using positively charged toner, so part of the original was made with negative image polarity and the other part was made with positive image polarity. Easy copying with correct image polarity. Furthermore, since the range in which the polarity is to be changed can be indicated using spot light, the instruction is simple (easy) and has good operability.

Further, it is possible to easily draw drawings, designs, etc., and create posters, flyers, etc.

In the above embodiments, the case where the image polarity is changed is explained at one location, but the present invention is not limited to this, and it can be implemented in the same manner even when changing the image polarity at a plurality of locations.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to easily form an image on a part of one document with a polarity different from that on other parts, and it is possible to easily form an image on a part of one document with a polarity different from that on the other part. It is possible to provide an image forming apparatus that allows easy instructions.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a flowchart for explaining a partial reversal operation, FIG. 2 is an external perspective view of the image forming apparatus, and FIG. 3 is a side sectional view of the image forming apparatus. , filW4 is a plan view showing the configuration of the operation panel,
Fig. 5 is a diagram showing an example of the display on the display section, Fig. 6 is a perspective view schematically showing the driving mechanism of the optical system, Fig. 7 is a component showing the overall control circuit, and Fig. 8 is a spot light source. FIG. 9 is a side sectional view of the main part showing the spot light source, and FIGS. 10 and 11 are plane views shown to explain the operation of specifying the erasing range of the document using the spot light source, respectively. figure,
Figure 12 is a diagram shown to explain the contents of the memory.
Figure 3 is a side sectional view of the main part showing the arrangement of the erasing array;
Figures 1 and 1'5 respectively show the relationship between the erasing array and the photosensitive drum, Figure 14 is a perspective view showing only the main parts, Figure 15 is a front view showing only the main parts, and Figure 16. 17 shows the configuration of the erasing array, FIG. 17(a) is a side sectional view, FIG. 17(b) is a partially cutaway front view, and FIG. 17 is a circuit diagram showing the configuration of the array drive section. , Figure '18 is a diagram showing an example of the display on the display unit during partial inversion copying,
The figure is a diagram showing an example of a document to which partial inversion copying is performed, No. 20.
21 is a diagram showing an example of copying paper on which partial inversion copying has been performed, FIG. 22 is a sectional view showing the configuration of a developing device, and FIG.
The figure is a diagram for explaining the relationship between the charging potential of the photosensitive drum and the developing bias voltage when normal development and reversal development are performed. DESCRIPTION OF SYMBOLS 1...Main body, 2...Document table, 10...Photosensitive drum, 11...Charging device, 12...Developing device, 18
...Transfer charger, 30...Operation panel, 302.
...Display section, 30a to 30d...Operation keys, 30e.
...Position designation key, 31a-31h...Selection key, 3
3...Pulse motor, 71-...Main control section, 76a,
76b, 76G...Power supply circuit, 131...Spot light source, 135...Pulse motor, 140...Memory, 141a. 141b...Switching circuit, 150...Erasing array, 1
60...Array drive unit, 170...Developing sleeve,
P... Paper, ph... Exposure section, W... Frame, Wa...
...Inner edge of the frame, wb...Outer edge of the frame. Applicant's representative Patent attorney Takehiko Suzue Figure 11 Figure 12 Figure 14 (a) (b) Figure 16

Claims (3)

[Claims] (1) A scanning device that optically scans a document placed on a document table; an optical system that forms an optical image obtained by the scanning device onto a charged image carrier; and the image carrier. In an image forming apparatus comprising a developing means for developing an image formed on a body, and a transfer means for transferring the developed image onto a transfer material, the developing means has a charge polarity of both polarities. an indicating means using a component-based magnetic developer, provided in the scanning means, and indicating a predetermined range in which the polarity of the document is to be changed using a spot light; an erasing means for erasing an image or an image inside the range indicated by the spotlight from the image carrier; and an original from which the erasing means erases the image inside the range indicated by the spotlight by the indicating means. An image corresponding to the image is formed on a transfer material using a developer with a transfer voltage of the transfer means having the same polarity as that of the image carrier and one of the charging polarities of the development means, and this transfer material is again transferred to the transfer means. The image corresponding to the original image erased by the erasing means from the image outside the range indicated by the spotlight is transferred to the developing means with the transfer voltage of the transfer means being opposite in polarity to that of the image carrier. An image forming apparatus comprising: a control means for forming on the transfer material using a developer of the other charged polarity. (2) The image forming apparatus according to claim 1, wherein the image based on the polarity is a positive image or a negative image. (3) The image forming apparatus according to claim 1, wherein the erasing means is constituted by a line array of light emitting elements.