JPS63236061A - 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 using a one-component magnetic developer in which both electrification polarities are mixed, and providing a means for instructing a prescribed range for changing the polarity in the original. CONSTITUTION:A prescribed range for changing the polarity in an original is instructed, and an image corresponding to an original image which has been erased from an image of the inside of this instructed range is formed on a material to be transferred by a developer of one electrification polarity of a developing means (developing sleeve) 170, by the same polarity as an image carrying body (photosensitive drum) 10 with respect to a transfer voltage of a transfer means (electrifying body for transfer) 18. Also, an image corresponding to an original image which has been erased from an image of the outside of the instructed range is formed on the material to be transferred by a developer of the other electrification polarity of the developing sleeve 170, by the opposite polarity to the photosensitive drum 10 with respect to the transfer voltage of the electrifying body 18. In such a way, a part of one original can be brought to an 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, a copying machine has a function of copying an original image directly onto a sheet of paper, or enlarging or reducing the original image to make a copy. Recently, there have also been methods to copy images by erasing images within a predetermined range of a document (masking), or methods to copy by erasing images outside a predetermined range (trimming).
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 that can perform 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. An object of the present invention is to provide an image forming apparatus that can easily form an image with a part having a polarity different from that of the other part.

[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;
an optical system that forms a qq optical image onto a charged image carrier; a developing device that develops the image formed on the image carrier; and a developer that transfers the developed image to a transfer material. a transfer means, in which the developing means uses a one-component magnetic developer in which charge polarity is a mixture of both polarities, and an instruction means for instructing a predetermined range in which the polarity of the original is to be changed; images outside the indicated range,
Alternatively, an erasing means for erasing an image inside the designated range from the image carrier, and an image corresponding to the original image erased by the erasing means from the image inside the range designated by the indicating means. A transfer voltage of the transfer means is applied to the transfer material using a developer having the same polarity as the image carrier and one of the charged polarities of the development means, and this transfer material is again conveyed to the transfer means, and the transfer voltage is applied to the transfer material according to the above instructions. An image corresponding to the original image erased by the erasing means from the image outside the range is transferred to the image by the developer of the other charged polarity of the developing means with the transfer voltage of the transfer means being opposite to that of the image carrier. It consists of control means for forming the material into the material.

(Operation) This invention specifies a predetermined range in which the polarity of a document is to be changed, and transfers an image corresponding to the erased document image from an image inside the specified range by changing the transfer voltage of the transfer means to the same level as that of the image carrier. An image corresponding to the original image is formed on the transfer material using a polarity developer of one side of the developing means, and is erased from the image outside the specified range, by changing the transfer voltage of the transfer means to the image carrier. The image is formed on the transfer material using a developer having opposite polarity and charging polarity on 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.
Near the document table 2, a document cover 11 and a work table 12, which can be opened and closed, are provided.

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
．． 93 and is guided to the photoreceptor drum 10 composed of a selenium drum, and the image of the document is reflected on the photoreceptor drum 10.
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 (material to be transferred) P is sent out from the selected upper paper feed cassette 131, middle paper feed force rollers 1 to 132, or lower paper feed cassette 133 to feed rollers 141, 142, 1.
43 and roller pairs 151, 152, and 153, the sheets are taken out one by one, passed through a paper guide path 161, 162, and 163, and guided to a pair of registration rollers 17, and guided to a transfer section by this pair of registration rollers 17. ing. 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.
The cassette sizes 132 and 133 are detected by cassette size detection switches 6o1, 6o2, and 603, respectively. This cassette size detection switch 6
01.602.603 is 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 1o 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.

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, a pair of paper discharge rollers 24, and a gate 23 for the above-mentioned sorting.
A plurality of roller pairs 28b128C128d are provided to guide the sheets taken in by the stacking section 28a to the stacking section 28a. 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 feed roller 28e is adjusted to the thickness (number of sheets) of the stored paper.
It is possible to move up and down as indicated by the arrow in the figure. The paper sent out by the delivery roller 28e is transferred to a separation roller pair 28 that separates the paper sheets one by one and sends them out.
It is guided to the control gate 28g via f. When performing multiple copying, this control gate 28Q is rotated in the direction of the arrow M shown in the drawing, and the paper is transported to the pair of conveying rollers 28h1 and the paper guide path 28.
1 to the pair of registration rollers 17.

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 28CI 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 registration roller pair 17 via the paper guide path 28i.
It is designed to guide you to. In this embodiment, the control gate 280 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, 31c, 31d, 31e for selecting the mode displayed on this display section 302.
, 31f, 31(], and 31h are provided.

Further, the operation panel 30 includes operation keys 30a, 30b, 30C130d1 for moving the spot light source indicating the erase position of the original to be erased and the gradation change position, and a position designation key 30e for inputting the coordinate position indicated by the spot light source.
is provided.

As shown in FIGS. 5(a) and 5(b), the display unit 302 displays the status of the device, etc. in text, and as shown in FIG. 5(C), trimming, masking mode, and image movement mode. , 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, figure(
As shown in d) to (q), the screen for selecting one or two originals in image mode, the screen for setting the number of copies, the screen for selecting copy magnification, and the screen for copying status are now displayed graphically. There is.

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 and 412 are guided by guide rails 42s and 422 in the direction of arrow a. It can be moved in parallel. That is, 4
Phase pulse motor 33 drives pulley 43. An endless belt 45 is connected between the pulley 43 and the idler pulley 44.
The mirror 5 is placed in the middle of this belt 45.
One end of the first carriage 411 that supports the is fixed. On the other hand, the second carriage 42 supporting the mirror 6.7
Two pulleys 47 and 47 are rotatably provided on the second guide portion 46 and spaced apart in the axial direction of the rail 422.
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, a first wire is provided in the middle of the wire 48.
One end of the carriage 411 is fixed. 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. Note that the moving directions of the first and second carriages 411 and 412 are 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. When the copy key 301 is pressed, the first 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 41
1 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 reverse development 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 11
A negatively charged toner (negative polarity toner; toner with opposite polarity to the photoreceptor drum 10) using a styrene-acrylic resin with a diameter of 10 μm as the main resin, and a positively charged toner using a styrene-acrylic resin with an average particle size of 10 μm. A positive polarity toner (positive polarity toner m; 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.
．． 5KV, and use the negatively charged toner O in the developing device 12. As shown in the same figure (see a>), when performing reversal development of a positive negative, the photosensitive drum 10 is positively charged at +700 cm, and the developing Bias voltage +400V,
The transfer voltage is set to -4.3 KV, and development is carried out using positively charged toner (2) 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.
．． A power supply circuit 7 that detects an input from an input device 75 such as 602 or 603 and applies a voltage to the charger 11 for charging.
6a1 power supply circuit 76b1 for applying a bias voltage to the developing sleeve 170 in the developing device 12; the transfer charger 1;
8, 27a controls 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, and also controls the spot light source 131, pulse motor 33, 135, memory 1401, and erase array 1.
50, 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 35, erasure array 150, array drive section 160, and memory 40 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 reverse vision.

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.

Further, the spot light source 131 is connected to a timing belt (toothed belt) 134 disposed along the guide shaft 130. 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 1
31 is moved in a direction perpendicular to the scanning direction of the first carriage 411. In addition, the pulse motor 1 of the guide shaft 130
A position sensor 138 consisting of a microswitch that detects the initial position of the spotlight 1131 is provided on the first carriage 411 located at the end of the spotlight 1131 . For example, when the spora 1 to the light source 131 are moved, the spot light source 131 first comes into contact with the position sensor 138 and the initial position is detected.

Next, a method for specifying the erasing range of a document using the spot light source 131 will be described with reference to 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 21 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 30b and 30d are pressed, the motor 33 is driven, and the first carriage 411 and the spot light source 131 are moved in the scanning direction (the direction of the arrow X shown in FIG. 10). In addition, the operation keys 30a, 30
When G is pressed, the motor 135 is driven and the spot light source 1
31 is perpendicular to the scanning direction (arrow X shown in FIG.
direction).

When specifying the partial reversal mode, the operator operates the operation keys 30a 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. 11, a rectangular area with diagonal points of the outer edge wb of the frame 21-21 = W as shown in FIG. is designated as the erasing range for regular development (reference image polarity).

Also, in the frame W formed by the S1 point and the 82 points, the area other than the rectangular area whose diagonal points are the 5tff' point and the 82F' point of the inner edge Wa is designated as the erasing range for reversal development with the other (image) polarity. be done.

In this way, when the erasing range is specified, the main control unit 7
1, and the memory 140 stores a high level signal IT I IT in the erasing range part and a low level signal "0°" in the other part. That is, this memory 140 stores, for example, each column. It is constituted by a RAM whose capacity in the direction is approximately equal to the moving distance of the spot light source 131 in the X direction divided by the position resolution in the y and X directions, and one image polarity (reference image polarity) is determined by data supplied from the main control unit 71. In the case of , 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 y 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 serving 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 voltage mVCC 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 stored between the erasing array 150 and the exposure section PH, for example.
Assuming that the angle h is θ and the photosensitive drum 10 is rotating at each speed, the output timing of the latch signal LT is controlled so that it is supplied to the store register 162 before θ1/'ω. ing.

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 parts of the photoreceptor drum 10, the part where the light emitting element 152 is turned on is charge-free, and even if the charge-free part is exposed afterwards, no electrostatic latent image is formed, and the original image is not erased. It means that it was done. Thereafter, the data in the memory 140 is read out one column at a time in the same manner, 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 image polarity change is displayed for the selection key 318, as shown in FIG. 18(a), and a pattern of the original 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 30a to 30d.
and position designation key 30e to designate point S1 and point 82 as the polarity change range on the document G (ST
7). Then, the inner edge Wa1 and outer edge Wb1 of the frame W in the range specified by the spot light source 131, that is, 81
” point, the position of two points of 52-one point and one point of $1,
The control section 71 performs calculations based on the positions of the two points, one point S2, and the memory 140 stores the spot light as erase data of the reverse development (negative) portion, as shown in FIG. 12(a). A high level signal is stored in an address corresponding to the inner side from the outer edge wb of the frame W by the spot light source 131, and a low level signal is stored in an address corresponding to the outer side from the outer edge wb of the frame W by the spot light source 131. As the erased data, as shown in FIG. 12(b), the inner edge Wa of the frame W caused by the spot light source 131
A high level signal is stored at an address corresponding to the outside from the spot light source 131, 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 spot light source 131 (S
T8).

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.
Exposure scanning is performed (ST9).

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 using negative polarity toner only in a portion other than the area surrounded by the outer edge wb of the spot light W of the original G. 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, using the developing device 12 containing positive polarity toner and negative polarity toner and the erasing array 150, the original G
The copying operation of the polarity changed portion is performed. That is, the first
The 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). Also, at this time, the switching circuits 141a and 141b are controlled by the reverse development signal from the main control section 71, so that voltages of -4 and 3 are applied to the transfer charger 18, and the voltage is applied to the development sleeve 170. +400 volts is applied as a developing bias voltage during reversal development (ST13-).

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 part of a document with negative image polarity and copying other parts with positive image polarity, it is necessary to use a one-component magnetic developer with a mixture of charge polarities of both polarities. By developing and setting the transfer voltage polarity to the same polarity as the photoconductor drum during positive PA m image and opposite polarity to the photoconductor drum during reversal development, the inside of the indicated range is erased and the transfer voltage is negative. Copy using charged polarity toner,
The second time, I erased the outside of the specified range and copied using toner with positively charged polarity, so I was able to copy part of the original with negative image polarity and the other part with positive image polarity. . In addition, the range to change the polarity can be indicated using a spot light, making it easy to indicate.
It 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 provide an image forming apparatus that can easily form an image on a part of a document with a polarity different from that on other parts.

[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. , FIG. 4 is a plan view showing the configuration of the operation panel, FIG. 5 is a view showing an example of the display section, FIG. 6 is a perspective view schematically showing the drive mechanism of the optical system, and FIG. 7 is an overall view. FIG. 8 is a perspective view of the main parts showing the spot light source.
FIG. 9 is a side sectional view of the main part showing the spot light source, FIGS.
The figure is a diagram for explaining the contents of the memory, FIG. 13 is a side sectional view of the main part showing the arrangement of the erasing array, and FIGS. 14 and 15 show the relationship between the erasing array and the photosensitive drum, respectively. FIG. 14 is a perspective view showing only the main parts;
Figure 5 is a front view showing only the main parts, Figure 16 is a diagram showing the configuration of the erasure array, Figure (a) is a side sectional view,
b) is a front view with a portion cut away, FIG. 17 is a circuit diagram showing the configuration of the array drive section, FIG. 18 is a diagram showing an example of display on the display section during partial inversion copying, and FIG. 19 is a partial view. Figures 20 and 21 are diagrams showing an example of a document on which reverse copying has been performed;
23 is a cross-sectional view showing the structure of the developing device, and FIG. 23 is a diagram for explaining the relationship between the charging potential of the photosensitive drum and the developing bias voltage in the case of normal development and reversal development. DESCRIPTION OF SYMBOLS 1...Main body, 2...Document stand, 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, 318-31h...Selection key, 3
3...Pulse motor, 71...Main control section, 76a
, 76b, 76c...power supply circuit, 131...spot light source, 135...pulse motor, 140...memory, 141a, 141b...switching circuit, 150...
Erasing array, 160...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 instruction means for instructing a predetermined range in which the polarity of the original is to be changed using a component-based magnetic developer; an erasing means for erasing from the carrier, an image corresponding to the original image erased by the erasing means from an image inside the range indicated by the instruction means, and a transfer voltage of the transfer means having the same polarity as that of the image carrier; The original is formed on a transfer material using a charged polar developer of one of the developing means, this transfer material is again conveyed to the transfer means, and the image outside the designated range is erased by the erasing means. control means for forming an image corresponding to the image on the transfer material using a developer having a polarity opposite to the transfer voltage of the transfer means and the other charge polarity of the developing means; Features of the image forming device. (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.