JP3441554B2 - Two-color image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-color image forming apparatus, and more particularly to a digital electrophotographic two-color image forming apparatus for synthesizing two color toner images on a photosensitive member.

[0002]

2. Description of the Related Art A digital electrophotographic copying apparatus which reads an original image, converts it into a digital signal, and writes the image on the basis of the digital signal to form an electrostatic latent image corresponding to the original image has become widespread. In addition to copying original images, OA for computers, word processors, etc.
It has become possible to record information created by a device, and the general concept of "image forming apparatus" is being established apart from the concept of copying apparatus.

As such an image forming apparatus, one capable of forming a color image has already been put into practical use, but it is rather a special field that color image formation is required in daily office work. It is limited, and is intended to be put into practical use for a two-color image forming apparatus which is often requested in relation to daily office work.

As such a two-color image forming apparatus, each of which is provided with two exposure devices and two development devices, an electrostatic latent image corresponding to a black image is written and formed by the first exposure device, and the formed latent image is formed. By developing the image with the black toner by the first developing device, writing and forming the electrostatic latent image corresponding to the red image with the second exposing device, and developing the obtained latent image with the red toner by the second developing device. , A method of synthesizing two color images of red and black on the same photoreceptor and transferring and fixing the synthesized color image of two colors of red and black on the same transfer paper to obtain a two color image is intended. There is.

As an exposure device for writing and forming an electrostatic latent image on a photosensitive member, a "light beam scanning type optical writing device" known in connection with an optical printer can be used, but it is considerably large. Therefore, as the first and second exposure apparatuses,
When such an optical writing device is provided, the layout around the photoconductor is difficult, and the two-color image forming apparatus tends to be large.

Therefore, at least one of the exposure apparatuses is preferably a "line type exposure apparatus" which is compact in terms of equipment, but the line type exposure apparatus is expensive, and by using this, two-color image formation is performed. The cost of the device may increase.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a compact and low-cost two-color image forming apparatus.

[0008]

The "two-color image forming apparatus" of the present invention is a "digital electrophotographic two-color image forming apparatus for synthesizing two color toner images on the same photosensitive member".
, And the shall be the feature the following points.

That is, the second exposure device for writing the electrostatic latent image corresponding to the "less used image" of the two colors to be combined has the "writing line direction" parallel to the width direction of the photoconductor. The "line type exposure device" has an exposure width smaller than the "maximum transfer paper width", and the "developing width" of the second developing device for developing the electrostatic latent image is smaller than the maximum transfer paper width and the "second exposure paper". The maximum latent image width formed by the device can be developed.

The "photosensitive member width direction" means a direction parallel to the photosensitive member surface in a direction orthogonal to the moving direction of the photosensitive member surface.

The color of the two-color image formed is basically arbitrary, but in the most general case, it is two colors, red and black. Digital signals for writing these two-color images on the photoconductor are obtained by reading a two-color original document or by designating an area in an information image converted into image information from text information.

The above-mentioned "image of the less frequently used of the two colors to be combined" is generally a red image in the case of a red / black two-color image.

The "line type exposure apparatus" controls blinking of minute light source elements such as LEDs closely arranged in one row by a digital image signal, and emits light emitted from each minute light source element by a rod lens array. It is an exposure apparatus that forms an image on a photoconductor by an array of "equal magnification erect image forming elements" such as a Dach mirror lens array or the like, and the arrangement direction of the minute light source elements is the "writing line direction". .

In this specification, "width" means a length associated with the arrangement direction of the minute light source elements in the second exposure apparatus, that is, the "writing line direction".

Therefore, the array length of the micro optical elements gives the above "exposure width". The maximum width of the electrostatic latent image that can be formed by writing by the second exposure device (substantially equal to the exposure width) is the "maximum latent image width formed by the second exposure device".

The above-mentioned "maximum transfer paper width" is the maximum length of the transfer paper that is passed through the transfer section in the direction parallel to the writing line direction, which is approximately the same as the width of the photoconductor. is there. The "developing width" of the second developing device is also the length of the area that can be developed by the second developing device in the direction parallel to the writing line direction.

Used by the first exposure device , as described below.
The image of the one with the higher frequency is exposed, and the image is formed by this exposure.
The electrostatic latent image to be developed by the first developing device and then the second exposure
Depending on the device, an electrostatic latent image corresponding to the image that is used less frequently
Write an image and the electrostatic latent image formed by this writing
The second developing device causes the toner of a color different from that of the first developing device.
It is configured to be developed with a toner. First exposure apparatus and
A first developing device, a second exposing device and a second developing device;
Are at different positions in the moving direction of the photoconductor surface.
Is located in. The second exposure device and the second developing device are
It is possible to move integrally in the writing line direction in the exposure device.
And write and develop images of colors that are rarely used.
It can be performed at any position within the formable region (claim 1).

In this case, the driving device of the second developing device can be configured to be movable together with the second developing device in the writing line direction of the second exposure device (claim 2 ).

In the two-color image forming apparatus according to the first or second aspect, it is possible to configure so that "the density control sensor is integrated with the second developing device and is movable in the writing line direction in the second exposure device". Claim 3 ).

In the arbitrary two-color image forming apparatus described in claims 1 to 3 , the first exposure device may be a line-type writing device like the second exposure device (provided that the first exposure device is a line type writing device. In this case, the exposure width needs to be a size capable of exposing the photoconductor width area corresponding to the maximum width of the transfer paper), or may be a "light flux scanning type optical writing device" (claim).
4 ).

In the two-color image forming apparatus according to any one of claims 1 to 4 , the exposure width of the second exposure device may be, for example, about 2/3 of the width of the photosensitive member, or The width may be about ½ of the body width, or may be “about ⅓ of the width of the photoconductor” (claim 5 ).

[0022]

When a two-color image is formed, generally, the two colors for forming an image are rarely used with equal frequency, one color is mainly used, and the other color is supplementarily used. It is usually used.

For example, in the case of general "red / black two-color" image formation as a two-color image formation, the image formation normally performed is mainly a black image formation, and a red image is recorded. In most cases, an image is formed in a "one-point" area, as in the case of recording an image of a stamp or a so-called "confidential" display.

That is, in a general usage situation of the two-color image forming apparatus, it is only exceptional that the red image occupies the entire image formable area, and the red image formed is usually , Limited to a relatively small area.

Further, most of the above-mentioned stamps and confidential displays are often in “fixed position” such as “right shoulder of image”.

Considering these points, the less frequently used image such as the red image does not need to be exposed to "the full width of the photoconductor" to form the electrostatic latent image corresponding thereto. In most cases.

Therefore, in the present invention, as described above, the second exposure device for writing the electrostatic latent image corresponding to the less frequently used color image is a line type exposure device, and its exposure width is larger than the maximum transfer paper width. The developing width of the second developing device is made smaller than the maximum transfer paper width, and the maximum latent image width formed by the second exposing device is set to a size capable of developing.

As described above, in the case where the stamp or the confidential display is in the "fixed position" like the right shoulder of the image, the second exposure device and the second developing device are set to the photosensitive member. It can also be "fixedly provided" at a predetermined position in the width direction.

[0029] As the invention of claim 1, wherein the second exposure apparatus and the second developing device, since it is moved together to the write line direction of the second exposure apparatus, less frequently used colors of the image Can be written and developed at any position in the image formable area.

[0030]

EXAMPLES Specific examples will be described below.

First, referring to FIGS. 2 and 3, a description will be given of "a digital electrophotographic two-color image forming apparatus for synthesizing two color toner images on the same photosensitive member" which is a premise of the invention.

FIG. 2 is a view showing a structure capable of forming an image of two colors of red and black.
A "two-color digital copying apparatus" as a color image forming apparatus is shown.

An upper part of the copying apparatus main body is an original reading device 2 having an ADF (automatic original feeding device) 1 mounted thereon, and a lower part of the original reading device 2 is an electrophotographic printer section. .

The document reading device 2 illuminates and scans a document directly set on the contact glass 4 or a document fed and set on the contact glass 4 by the ADF 1 by illuminating and scanning with an exposure lamp 5 and reflecting light from the document. The mirror / lens optical system 6 forms an image on the light receiving surface of the reading unit 7 having a solid-state image sensor such as a CCD line sensor, and the reading unit 7 converts the image into an electric signal for reading.

That is, in FIG. 2, after inputting copy data such as the number of copies by operating the ten-key pad of the operation unit (not shown), when the copy button is pressed, the contact glass 4 is pressed.
A reading operation based on illumination scanning is started for a document set on the ADF 1 automatically or manually.

The reading section 7 color-separates the original image into red / black, as described later, and converts the image information of each color into an electric signal. This electric signal is subjected to necessary image processing by an image processing unit, which will be described later, and is output to the first and second exposure devices of the printer unit, respectively.

The printer section has a photoconductor 3 which is photoconductive and is formed in a drum shape.
An exposure device 9, a first development device 10, a second exposure device 11, a second development device 12, a transfer device 13, and a cleaning device 14 are provided.

The first exposure device 9 and the second exposure device 11 are adapted to perform writing for forming a latent image on the photoconductor 3 at different positions in the device space, and correspond to a black image of a document. The writing information is written by the first exposure device 9.

The writing information for the red image is temporarily stored in the memory as described later, is output at a timing delayed by a predetermined time from the writing information for the black image, and is written by the second exposure device 11.

At the time of image formation, the photoconductor 3 is uniformly charged to a predetermined polarity by the charger 8, and first, the first exposure device 9 performs writing according to the writing information of the black image to form an electrostatic latent image. Is visualized with black toner by the first developing device 10.

The "electrostatic latent image corresponding to the red image" formed by writing by the second exposure device 11 is visualized by the second developing device 12 with red toner. In this way, the two color toner images of red and black are combined on the photoconductor 3 to obtain a two color toner image.

The transfer paper 17 to which the two-color toner image is transferred is fed from the paper feed tray 15 by the paper feed roller 16, temporarily stopped by the registration roller 18, and then the two-color toner on the photoconductor 3 is transferred. The image is sent toward the transfer unit in synchronization with the movement of the image.

The transfer paper 17 sent in is a conveyor belt 19
Is conveyed to the transfer section. In the transfer section, the transfer device 13
A corona discharge for transfer is applied toward the back surface of the transfer paper 17,
The two-color toner image on the photoconductor 3 is transferred onto the surface of the transfer paper 17.

The transfer paper 17 onto which the two-color toner image has been transferred is conveyed to the fixing device 20 by the conveyor belt 19 and the two-color toner image is fixed. In this way, a two-color image is obtained on the transfer paper 17. When copying is performed on both sides of the transfer paper 17, the transfer paper 17 is reversed upside down and then conveyed again to the position of the registration roller 18 through the conveyance path for copying on the back side. Is transferred and fixed on the back side.

The transfer paper on which a desired two-color image is formed on one side or both sides is discharged to the outside of the apparatus.

FIG. 3 is a diagram for explaining the first exposure device 9. The light beam emitted from the semiconductor laser 21 is collimated by the collimator lens 22 and emitted from the laser unit 23, and is converged only in the sub-scanning corresponding direction by the cylinder lens 24 and corresponds to the main scanning in the vicinity of the deflective reflection surface of the polygon mirror 26. It forms a long line image in the direction.

When the polygon mirror 26 is rotated at a high speed by the motor 25, the light flux reflected by the deflecting / reflecting surface is deflected at a constant angular velocity, and is transferred onto the photoconductor 3 via the anamorphic fθ lens 27, the reflecting mirror 28 and the dustproof glass 30. The light is guided and focused on the photoconductor 3 as a light spot by the action of the fθ lens 27, and the photoconductor 3 is optically scanned to perform writing.

The light beam deflected by the polygon mirror 26 is detected by the synchronization detection sensor 32 via the reflecting mirror 31 before the scanning of the photosensitive member 3, and the starting points of writing in the optical scanning are aligned based on the detection result. The writing timing is controlled. The entire first exposure device 9 is housed in a housing 29.

FIG. 1 shows the invention according to claim 1 as shown in FIG.
It is a figure for explaining a characteristic portion of an example applied to a color digital copying apparatus.

In FIG. 1A, reference numeral 110 is a second exposure device, and reference numeral 120 is a second developing device. Second
The exposure apparatus 110 is a "line type exposure apparatus", and is shown in FIG.
LED array chip 11 in which minute LEDs are closely arranged in the direction orthogonal to the drawing in accordance with the writing density, as shown in FIG.
2 and the LED array chip 112 for driving the same.
IC drive circuit 1 connected by wire bonding with
13 and a “rod lens array” in which rod lenses 114 are closely arranged in a direction orthogonal to the drawing are integrated by a housing 115.

The inside of the housing 115 is hermetically sealed and LE
The D array chip 112 and the IC drive circuit 113 are prevented from being contaminated with toner.

As shown in FIG. 1B, when an arbitrary LED in the LED array chip 112 is caused to emit light, the image of the light emitting portion of the turned-on LED is formed on the photoconductor 3 by the image forming action of the rod lens 114. To be imaged.

FIG. 1C shows a state in which the second exposure device 110 is viewed from the side of the photoconductor 3, the arrangement direction of the rod lenses 114 is the "writing line direction", and the area indicated by the symbol A is the first. 2 “Exposure width” by the exposure device 110.

As shown in FIG. 1A, the second exposure device 1
The housings of 10 and the second developing device 120 are integrated.

The second developing device 120 has a device width substantially the same as that of the second exposure device 110 in the writing line direction so that the "maximum latent image width" written by the second exposure device 110 can be developed. It has become.

The second developing device 120 engages with a rail 130 provided along the generatrix direction of the photoconductor 3, and along the rail 130, in the "writing line direction" integrally with the second exposure device 110. It can be displaced.

That is, a drive motor 150 is provided near the end of the photosensitive member in the writing line direction, and a pulley (not shown) provided at the opposite end and the drive motor 1 are provided.
A wire 140 is wound around the drive pulley 151 of the second 50, and the end of the wire 140 is attached to the second developing device 120.
Locking projections 121, 122 formed on the upper part of the housing of the
Is locked to.

Therefore, the forward / reverse rotation of the drive motor 150 makes it possible to move the second exposure device 110 and the second developing device 120 integrally in any direction of the writing line direction.

A light-shielding plate 111 for position detection is provided on the top of the housing 115 of the second exposure apparatus 110. As shown in FIG. 1D, a plurality of photosensors 141 are arranged at predetermined positions along the moving area of the light blocking plate 111 according to the movement of the second exposure device 110, and the light blocking plate 111 is detected. By doing so, the second exposure device 110 and the second developing device 120 can be positioned at a “predetermined position” in the writing line direction.

In this embodiment, the second exposure device 110
The exposure width and the developing width of the second developing device 120 are about 1/3 of the width of the photoconductor 3 (claim 5 ), and the second exposing device 110 and the second developing device 120 are arranged in the photoconductor width direction. , The central part, the right part, and the left part can be written and developed in three areas (the end parts are overlapped to each other to some extent), and the operation position corresponding to each of the above three areas can be set. The three photosensors 141 are provided at predetermined positions so that they can be positioned.

The two-color copying operation in the embodiment under description will be described with reference to FIGS. 4 and 5. FIG. 5 shows the “operation unit”. The operation unit 68 includes a liquid crystal display 70 for displaying operation modes and the like, and operation buttons 71 for inputting operation information such as the number of copies, magnification and start of copy operation (in the example of the figure, a ten-key and a touch panel on the display are shown. Equipped).

"Operation information" such as the number of copies, the magnification and the start of the copying operation, which are input by operating the operation button 71 of the operation unit 68, are output to the system controller 69 as shown in FIG. Further, the display content of the liquid crystal display 70 of the operation unit 68 can be switched by the information of the system controller 69.

In FIG. 4, the portion indicated by the reference numeral 33 indicates the "original reading portion" of the original reading apparatus indicated by the reference numeral 2 in FIG. 2, the portion indicated by the reference numeral 67 indicates the "image processing portion", and the reference numeral 40 indicates the first portion. An “exposure unit” including the first exposure device 9 and the second exposure device 110 and a drive system thereof is shown.

The document reading section 33, the image processing section 67, the exposure section 40 and the operating section 68 are connected to the system controller 69 via a bus line.

The system controller 69 sends a copy operation start signal, a synchronizing signal, and a magnification designation signal to the document reading section 33 and the exposure section 40, and sends an image processing mode designation signal (single color) to the image processing section 67. Mode, two-color mode designating signal, etc., and also an abnormal signal from each module and an operation status signal (wait, read).
y, busy, stop) to "control the entire system".

In response to a copy operation start signal from the system controller 69, the document reading section 33 performs illumination scanning of the document at a scanning speed corresponding to the designated magnification. Image information of the document is R (red), G (green), B (blue) filter 7
Solid-state image sensor (CCD image sensor) 39 that is color-separated by 2R, 72G, and 72B and corresponds to each filter
Is converted into an electric signal.

The output of each solid-state image pickup device 39 is converted into a digital signal by the corresponding A / D converter 73 and subjected to shading correction by the shading correction circuit 74, and then temporarily stored in the buffer memory 75 as "digital image data". Remembered.

This digital image data is processed by the image processing section 67.
Sent to. In the image processing unit 67, first, the γ correction circuit 76 γ-corrects the gradation of the digital image data according to the characteristics of the photoconductor and the first and second exposure devices.

The γ correction circuit 76 uses the information from the system controller 69 to select “black mode”, “red mode”, “red / red mode”.
The correction process is switched depending on the three modes of "black mode".

The signal output from the γ correction circuit 76 is sent to the black separation / color generation circuit 77. The black separation / color generation circuit 77 generates image data to be written by the first and second exposure devices according to the mode information from the system controller 69, and outputs it to the gradation processing circuit 78.

The gradation processing circuit 78 performs gradation correction processing according to the characteristics of the first and second developing devices based on the information from the system controller 69. The information of the system controller 69 here is the image processing mode,
For example, "character mode", "photograph mode", "text / photograph mode", "magnification", etc. can be increased.

The image data output from the gradation processing circuit 78 is temporarily stored in the frame memory 79.

The memory control circuit 82 is connected to the frame memory 79 and the ROM 81, reads image data from the frame memory 79 based on information from the system controller 69, and outputs write data by the first and second exposure devices.

The write data (black image data) by the first exposure device 9 is output to the laser driver 84 of the exposure section 40, and the electrostatic latent image corresponding to the black image data written by the light beam scanning is output by the first developing device. Developed with black toner.

On the other hand, the write data (red image data) by the second exposure device 110 is stored in the LED array driver 86 (FIG. 1B) of the exposure section 40 via the buffer memory 80.
By being output to the IC drive circuit 103), the writing timing time difference corresponding to the writing position difference between the first exposure apparatus 9 and the second exposure apparatus 110 is given. That is, the writing by the second exposure apparatus 110 is
The writing is started after a predetermined time from the writing by the first exposure device 9.

When two-color digital copying is performed, the system controller 69 obtains the information of the image data in the frame memory 79 through the memory control circuit 82, and the above-mentioned "central portion" is used as a writing area by the second exposure device 110. , "Right side" or "left side" is determined, and FIG.
The drive motor 150 shown in (a) is driven to operate the photo sensor 141 to set the second exposure device 110 and the second developing device 120 at desired writing positions.

At this writing position, the second exposure apparatus 1
The image data is input to 10, the red image data is written, and the formed electrostatic latent image is the second developing device 120.
To develop with red toner. In this way, a desired two-color toner image is formed on the photoconductor 3, and thereafter, the transfer / fixing process is executed as described above to obtain a two-color copy image.

In the ROM 81, there is a "secret mark pattern".
And the information of the "shaded pattern" are coded and stored, and the memory control circuit 82 can add the information of the ROM 81 to the image data read from the frame memory 79 based on the information from the system controller 69. it can.

Further, the memory control circuit 82 can perform processing such as "mirror processing, italics, shadowing, double copying, rotation" on the image data of the frame memory 79 based on the information from the system controller 69. The timing of reading can be changed.

The LED array driver 86 and the laser driver 84 shown in FIG.
Based on the information from 9, it is possible to switch the driving method such as switching between 1-dot multi-value writing and binary writing.

FIG. 6 schematically shows only a characteristic part of one embodiment of the invention described in claim 2 . In order to avoid complication, the same reference numerals as those in FIG. 1 are used for those which are considered not to be confused.

In FIG. 6, reference numeral 125 indicates a “driving device” for the second developing device 120, which is integrated with the second developing device 120.

In the embodiment of FIG. 1, only the second developing device 120 is integrated with the first exposing device 110,
Since the driving device for driving the driving device is provided on the immovable member on the apparatus main body side, "flexible driving force transmitting means" for transmitting the driving force from the driving device to the second developing device 120 is required, and the driving force transmission is required. The banding of the image is likely to occur due to the vibration of the second developing device 120 due to the above, but the banding of the image is minimized by integrating the driving device 125 with the second developing device 120 as in this embodiment. be able to.

FIG. 7 schematically shows only a characteristic part of one embodiment of the invention described in claim 3 . Also in this figure, in order to avoid complication, the same reference numerals as those in FIG. 1 are used for those which are considered to have no fear of confusion.

In FIG. 7, a "density control sensor" indicated by reference numeral 160 is movable with the second developing device 120 in the writing line direction in the second exposure device 110. "Density control" is the control of the density of the image to be formed, and is generally a "reference latent image pattern" on the photoreceptor.
The density control sensor optically detects the density of the toner pattern obtained by developing the latent image pattern and controls the "image forming conditions" so that the detected density becomes a predetermined reference density. ing.

In an image forming apparatus such as the two-color image forming apparatus of the present invention, which combines toner images of two colors on the same photoconductor, the image density control is performed for each color toner image to be combined. Needs to be done.

In the present invention, the second exposure device and the second
Since it can move in the writing line direction with the developing device,
If the installation position of the density control sensor is fixed at a fixed position in the writing line direction, in the density control prior to image formation, first, the second exposure device 110 and the second developing device 120 are first.
Are installed in accordance with the position of the density control sensor, and in this state, the reference latent image pattern corresponding to the reference density of red is written by the second exposure device 110, and this is written in the second developing device 120.
The density of the red toner pattern obtained by development is detected to set the image forming condition, and thereafter, the second exposure device 11
0 and the second developing device 120 need to be moved to a portion (center portion, left side portion, or right side portion) where red image data is written.

However, as in this embodiment, the density control sensor 160 (composed of a combination of a light emitting element and a light receiving element) is fixedly provided on the bottom surface of the second developing device 120, and By integrating them, since the positional relationship between the density control sensor 120 and the second developing device 120 is always immobile, the density control can always be easily performed regardless of the position of the second developing device 120.

Incidentally, the density control sensor 160 detects the density of the red toner pattern by irradiating the light of the light emitting element on the red toner pattern and detecting the intensity of the light reflected by the red toner pattern by the light receiving element.

[0090]

As described above, according to the present invention, a novel two-color image forming apparatus can be provided .
5 ). Since the two-color image forming apparatus according to the present invention has the above-described structure, the second exposure device and the second developing device can be effectively downsized and can be made compact.

"Line type exposure apparatus" which is the second exposure apparatus
, The higher the exposure width, the higher the cost.
Since the exposure width of the second exposure device is shorter than the "maximum transfer paper width", the two-color image forming apparatus can be realized at low cost by effectively reducing the cost of the second exposure device.

Since the invention according to claim 1 is configured as described above, an image of a color that is used less frequently can be formed at an arbitrary position in the image formable area, and the image forming position of the color can be freely set. The degree is high.

According to the second aspect of the present invention, since it has the structure as described above, there is no need for transmitting means for transmitting the driving force from the driving source to the second developing device, which simplifies the apparatus and also transmits the driving force. It is possible to effectively suppress the accompanying vibration and minimize the banding of the recorded image.

Since the invention according to claim 3 has the structure as described above, it is not necessary to align the second developing device with the density control sensor.

[Brief description of drawings]

FIG. 1 is a diagram for explaining only a characteristic part of one embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a two-color image forming apparatus to which the present invention can be applied.

FIG. 3 is a diagram for explaining the first exposure apparatus in the example shown in FIG.

FIG. 4 is a block diagram for explaining how to handle image data for forming a two-color image in the above embodiment.

FIG. 5 is a diagram illustrating an operation unit in the apparatus example of FIG.

FIG. 6 is a diagram showing only a characteristic part of one embodiment of the invention according to claim 2 ;

FIG. 7 is a diagram showing only a characteristic part of one embodiment of the invention according to claim 3 ;

[Explanation of symbols]

110 Second exposure apparatus 120 Second developing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G03G 15/01 112 B41J 3/21 L 117 H04N 1/04 (72) Inventor Tomoyuki Yoshida 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 in Ricoh Company Ltd. (72) Inventor Takashi Goto 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inventor Ricoh Company Ltd. (72) Shinji Kobayashi 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6, in Ricoh Co., Ltd. (56) Reference JP-A-60-153063 (JP, A) JP-A-57-185451 (JP, A) JP-A 1-275073 (JP, A) JP-A-60 -52882 (JP, A) JP 64-19377 (JP, A) JP 1-179069 (JP, A) JP 64-49064 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) G03G 15/04-15/04 120 B41J 2/44 B41J 2/45 B41J 2/455 G03G 15/01 112 G03G 15/01 117 H04N 1/04 G03G 21/00 370-512

Claims (5)

(57) [Claims] 1. In a digital electrophotographic two-color image forming apparatus for synthesizing two color toner images on the same photosensitive member, a first exposure device exposes an image of a more frequently used one.
The electrostatic latent image formed by this exposure is transferred to the first developing device.
To develop the image and use the second exposure device to handle the less frequently used image.
Write an electrostatic latent image, which is formed by this writing
The electrostatic latent image is transferred from the second developing device to the first developing device.
The first exposure device, the first development device, the second exposure device, and the second exposure device are configured to develop with toners of different colors.
And the second developing device are located in the moving direction of the surface of the photoconductor.
Then, the second exposure device for writing the electrostatic latent image corresponding to the less frequently used image of the two colors to be combined and arranged at different positions makes the writing line direction parallel to the photoconductor width direction. In the line type exposure device described above, the exposure width is smaller than the maximum transfer paper width, and the development width of the second developing device for developing the electrostatic latent image is smaller than the maximum transfer paper width. The size is such that the maximum latent image width to be formed can be developed , and the second exposure device and the second development device are arranged so that
It is possible to move integrally in the writing line direction of the device,
It is possible to write and develop images of infrequently used colors.
Two colors characterized by being able to be performed at any position within the Noh area
Image forming apparatus. 2. The two-color image forming apparatus according to claim 1 , wherein the driving device of the second developing device is movable together with the second developing device in the writing line direction of the second exposing device. And a two-color image forming apparatus. 3. The two-color image forming apparatus according to claim 1 or 2, wherein the density control sensor is integrated with the second developing device and is movable in the writing line direction of the second exposure device. Color image forming apparatus. 4. A two-color image forming apparatus of the mounting according to claim 1 or 2 or 3 SL, the first exposure apparatus, two-color image forming apparatus which is a optical writing device of a light beam scanning method. 5. The method according to any one of claims 1 to 4.
In the color image forming apparatus, the exposure width of the second exposure device is about ⅓ of the width of the photoconductor, the two-color image forming apparatus.