JP2608080B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus suitable for a color recording apparatus and a color display apparatus using various image forming methods, and more particularly, to an image forming apparatus formed on a plurality of independent image carriers. The present invention relates to a technique for preventing misregistration when an image is sequentially transferred onto a transfer material moving in a certain direction.

2. Description of the Related Art The applicant has proposed many image forming apparatuses in which a plurality of photoreceptors for forming a latent image by an electrophotographic method are arranged and a color image is formed on a transfer material (Japanese Patent Application Laid-Open No. S59-5959). −3197
No. 6, JP-A-59-62879). In such an image forming apparatus, it is important and difficult to solve so-called misregistration (also referred to as color misregistration or color misregistration).

Also, in the conventional general color copying apparatus, since the reflected light from the document is directly guided to the photoreceptor through the optical system, an analog exposure recording method for forming a latent image is adopted.
It has been said that the tolerance for misregistration is about 0.15 mm, which is the tolerance for human vision. However, in a recent digital image recording method in which dot recording is performed by a laser or the like based on an electric image signal, in an allowable value of about 0.15 mm, moire fringes occur due to misregistration of pixels, and the hue changes locally. There was a problem. The hue shift due to the moire fringes can be made inconspicuous by forming the screen angle of the screen for halftone dots.
58-85434), which is not an essential solution.
It is needless to say that correct superimposition recording in pixel units is an essential solution.

[Problems to be Solved by the Invention] However, digital image recording tends to increase in density year by year, and 12 pel (Pixel par milimetre), 16 pel
Alternatively, when high-density recording such as 400 dpi (dots per inch) is performed, it is extremely difficult to perform the above-described accurate superposition in pixel units.

Here, for example, in the recording of 16 pel, the pixel pitch is 1/16 mm (= 62.5 μm), and the conventional misregistration of 0.15 mm cannot be tolerated in order to correctly overlap each pixel.

On the other hand, a transfer device (see JP-A-59-155870), which determines the transfer timing for each transfer material based on a detection signal from a transfer detection means disposed upstream of each transfer position, and a recording material (transfer material). The present applicant has proposed a color image recording apparatus (see JP-A-59-163971) for individually setting the time from the detection of the means for detecting the transport position of the material to the start of the image forming operation for each color. However, since the pixel clock as a reference for determining the timing for each color must be common to each color, each pixel is recorded within a pixel pitch, i.e., within the pixel pitch, which is the recording time interval from a certain pixel to an adjacent pixel. It is difficult to perform registration that overlaps accurately. In addition, adjusting the pixel clock for registration cannot be performed because a change in magnification occurs. Similarly, it is not possible to adjust the transport speed of the transport belt that transports the transfer material (recorded material) for registration because a change in magnification occurs.

In view of the above-described problems, the present invention provides an image forming apparatus capable of eliminating misregistration and preventing the occurrence of hue shift caused by moiré fringes by accurately overlapping pixels. The purpose is to do.

[Means for Solving the Problems] In order to achieve the above object, an image forming apparatus of the present invention includes:
Image forming apparatus for sequentially transferring a plurality of images formed on each image carrier on a transfer material moving in a sub-scanning direction by periodically scanning a plurality of independent image carriers on a main scanning direction. Wherein the image formed on the upstream image carrier is transferred from the image forming position on the upstream image carrier to the image formed on the downstream image carrier on the transfer material. The difference between the time to move to the position and the time to move the image formed on the image carrier on the downstream side from the image forming position on the image carrier on the downstream side to the transfer position is the scan period. The plurality of image carriers are arranged so as to be substantially an integral multiple.

Here, a plurality of position adjusting means for finely adjusting the image forming positions on the plurality of image carriers may be provided.

Further, an image can be formed by periodically scanning the plurality of image carriers with a light beam.

Furthermore, an image can be formed by periodically scanning the plurality of image carriers with an LED array.

Still further, the transfer material may be recording paper conveyed by a conveyance belt moving in the sub-scanning direction.

[Operation] In the present invention, the image formed on the upstream image carrier is transferred from the image forming position on the upstream image carrier to the image carrier formed on the downstream image carrier by the transfer material. The difference between the time required to move to the transfer position to be transferred to the upper side and the time required for the image formed on the downstream image carrier to move from the image forming position on the downstream image carrier to the transfer position. However, since the plurality of image carriers are arranged so as to be substantially an integral multiple of the scanning period, an image forming apparatus such as adjusting the irradiation position of the laser beam in the sub-scanning direction or adjusting the irradiation start timing. Even if there is no need for various adjustments to correct misregistration after assembling, each pixel can be accurately overlapped on the transfer material by designing and manufacturing according to the present invention, eliminating misregistration and eliminating moire. It is possible to prevent the occurrence of caused by hue shift on.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of a schematic configuration of an image forming apparatus to which the present invention is applied. This apparatus incorporates three sets of electrophotographic laser beam printer mechanisms by Carlson process as a plurality of sets of image forming mechanisms. Is a color laser beam printer (color LBP).

In this figure, reference numerals 1, 2, and 3 denote electrophotographic photosensitive drums sequentially arranged at equal intervals from the right side to the left side of the drawing, which are used for image formation of yellow (Y), magenta (M), and cyan (C), respectively. , At a constant speed in the direction indicated by arrow 4 in the figure. Above these photosensitive drums 1, 2, and 3, laser scanners 5, 6, and 7 each including a semiconductor laser and a polygon mirror as described later with reference to FIG. Emits raster lines 8, 9, and 10 of laser light to expose the opposing photosensitive members 1, 2, and 3, respectively.

Reference numeral 11 denotes a transfer paper, which is conveyed onto a conveyance belt 12 by a feeding device described later in FIG.
The toner image is transferred through the transfer position of
After being discharged to the position indicated by 13, the color image is sent to a fixing device to be described later with reference to FIG. The transport belt is suspended around a drive roller 14 directly connected to a drive motor (not shown) or via a gear train, and a pair of driven rollers 15 and 16 at a constant speed in the direction of arrow 17 in the figure. The transfer paper 11 is transported.

Reference numerals 18 and 19 denote fine adjustment screws for finely adjusting the fixing positions of the laser scanners 5, 6, and 7, respectively, and are elongated holes as shown in FIG. 2 opened in the fixing member 20 such as a main body box (body). In the direction of transfer of the transfer paper 11 along the laser scanner 5,
6, 7 fixed positions can be moved in microns. Reference numeral 22 denotes a mounting arm for the laser scanners 5, 6, and 7. In this example, a laser scanner is used with screws 18 and 19.
The fine adjustment of the positions 5, 6, and 7 is performed, but the present invention is not limited to this. For example, a set screw used in a micrometer may be used.

FIG. 3 shows the configuration of one of the three laser scanners 5, 6, and 7 described above. The light beam modulated in accordance with the digital image signal by the semiconductor laser 51 is collimated by a collimating lens 52 and subjected to light deflection by a polygon mirror (rotating polygon mirror) 53. The deflected light beam forms an image on the surface of the photosensitive drum 1 charged by the primary charger by an imaging lens 54 called an fθ lens, and performs beam scanning in the drum generatrix direction. At the time of this beam scanning, the leading end of one line scanning of the light beam is
And is guided to a detector (detector) 56. As is well known, the detection signal from the detector 56 is used as an ID (index) of the image signal or a horizontal output timing control signal (BG signal) as a horizontal readout signal.

FIG. 4 shows a feeding device for feeding the above-mentioned transfer paper 11 and developing devices around the photosensitive drums 1, 2, and 3. In this figure, 57
Is a feeder (paper feed mechanism) located on the right side of the main unit box 20
The transfer paper 11 manually fed by an operator (operator) is carried into the printer mechanism at a predetermined timing. Around the photosensitive drums 1, 2, and 3, which are driven to rotate in the direction of arrow 4, a primary charger 58, a developing unit 59, a transfer charger 60, a cleaner 61, and the like are sequentially disposed in the drum rotating direction. I have. The raster lines 8, 9, and 10 of the laser light from the laser scanners 5, 6, and 7 scan the surface of the photosensitive drums 1, 2, and 3 charged by the primary charger 60 in the drum generatrix direction to expose the drum surface. Thereby, an electrostatic latent image is formed on the photosensitive drum. However, the yellow (Y) developer is used for the developing device of the first photosensitive drum 1, the magenta (M) developer is used for the developing device of the second photosensitive drum 2, and the developing device for the third photosensitive drum 3 is developed. The container contains a cyan (C) developer.

Reference numeral 62 denotes a photo-interrupter provided in front of the registration roller 57-2 for detecting a paper feed, and 63 denotes a transfer belt
The adsorption chargers fixedly adsorbed thereon and 64Y, 64M, 64C are photo interrupters provided on the upstream side of each printer mechanism. The leading end of the transfer paper 11 is a photo interrupter 64Y, 64M, 64
When C is cut off, image formation on each of the photosensitive drums 1, 2, and 3 of each printer mechanism is sequentially started by the detection signal. Reference numeral 65 denotes a photo interrupter that detects a joint of the conveyor belt 12.

FIG. 5 shows a configuration near the above-mentioned fixing device. In the figure, reference numeral 66 denotes a fixing device, 67 denotes a discharge outlet of the printed transfer paper 11 outside the apparatus, and 68 denotes a tray for storing the discharged transfer paper 11. Reference numeral 69 denotes a static eliminator for releasing electrostatic attraction between the transfer paper 11 and the transport belt 12.

 Next, the entire transfer operation will be briefly described.

First, when the power is turned on to the apparatus, the laser scanners 5, 6, and 7 of each printer mechanism are energized or rotated to other required process equipment, and the heater of the fixing device 66 is energized. , The device warms up. Then, when the laser is turned on, the scanner reaches a predetermined number of revolutions, and the fixing roller reaches a predetermined temperature, the printer device is in a ready state.

An operator feeds the transfer paper 11 as a recording member by a feeding device.
When it is inserted on the paper feed guide 57-1 of 57, its leading end is detected by the first photo interrupter 62 provided in front of the registration roller 57-2, and a start signal (start signal of a print sequence) is issued. With this start signal, the photosensitive drums 1, 2, and 3 of each printing mechanism start rotating. In addition, the driving roller 14 and the driven rollers 15 and 16 are simultaneously driven, and the transport belt 12 starts to move.

The transfer paper 11 is formed by a paper feed roller 57-
2. The sheet is fed onto the moving transport belt 12 through a sheet feed guide 57-3, a pair of rollers, a registration roller 57-4, and a sheet feed guide 57-5. The transfer paper 11 carried into the conveyor belt 12 is subjected to corona charging by the adsorption charger 63 and is fixedly adsorbed on the conveyor belt 12. In addition, this adsorption charger
A guide 57-6 made of a conductor as the counter electrode of 63 and connected to the ground is provided via the conveyor belt 12.

When the leading end of the transfer paper 11 shuts off the photo interrupters 64Y, 64M, 64C provided for each printer mechanism, the signal starts the image formation on each photosensitive drum 1, 2, 3 of each printer mechanism sequentially. . That is, a yellow image as a color component of a color image is assigned to the surface of the photosensitive drum 1 of the first printer mechanism, a magenta image is assigned to the second image, and a cyan image is assigned to the third image. It is formed. Since the principle of image formation in each printer mechanism is already well known, a description thereof will be omitted.

The transfer paper 11 is sequentially conveyed through the transfer positions below the first to third printer mechanisms in the direction of the fixing device 66 by the rotation of the conveyance belt 12, and the transfer charging of each mechanism is performed during the passage of each mechanism. The yellow image formed on the photosensitive drum surface of the first printer mechanism, the magenta image formed by the second mechanism, and the cyan image formed by the third mechanism are sequentially superimposed on the same surface of the transfer paper 11 by the unit 60. As a result, a color image is synthesized and formed on the sheet surface. When the transfer paper 11 passes through the third printer mechanism, the transfer paper 11 is discharged by the discharger 69 to which the AC voltage is applied, and is separated from the transport belt 12 by releasing the electrostatic attraction with the transport belt 12.

The transfer paper 115 having been released from the electrostatic attraction rides on the separation claw 70, is guided into the fixing device 66, and is fixed by the heat and pressure of the formed color image. It is discharged onto the outer tray 68.

After the transfer paper 11 is discharged outside the machine, the fixing device 66 is removed,
All the driving is stopped, and the one-cycle print sequence ends.

Next, the configuration and operation unique to the present invention will be described.

FIG. 6 schematically shows the pixels formed on the transfer paper 11. Interpixel recording time T ₃ of two adjacent raster lines 23 and 24 of the formation interval 25 is determined uniquely by the rotational speed and the number of faces of the polygon mirror 53 (see FIG. 3).

Further, in FIG. 1, and T ₁ indicating the time at which image from the image forming position of the first recording unit 5 (the beam irradiation position) to a second transfer position moves by the arrows in the drawing, the second recording means When the image 6 image forming position to the second transfer position to m an integer time to move as T ₂ indicated by the arrow in _{FIG., m × T 3 ≒ T 1} -T 2 ... (1) equation ( By arranging the elements of the recording means so as to satisfy 1), the pixels of the first color and the pixels of the second color can be correctly overlapped.

Laser scanners 5 and 6 with the accuracy shown in the above equation (1)
It is generally difficult to arrange the pixels, but if the position of the laser scanners 5 and 6 is moved by the fine adjustment screws 18 and 19 while observing the image transferred to the transfer paper 11, can do.

Further, the diameter of the drive roller 14 is R, and the transfer position interval H
Where n is an integer, n × π × R ≒ H (2) The values of R and H are set so that the above equation (2) is satisfied. In this case, the cycle of the drive unevenness of the drive roller 14 is expressed in synchronization with each transfer position interval, so that misregistration due to drive unevenness does not occur. This principle has already been shown by the present applicant in Japanese Patent Application Laid-Open No. Sho 59-182139 (corresponding US Pat. No. 4,531,828).

FIG. 7 shows another embodiment of the present invention. This embodiment is the first
Although substantially the same as the embodiment in the figure, the belt 12 is an intermediate transfer member for temporarily carrying an image. The image on the intermediate transfer body 12 is re-transferred onto the transfer paper 11 by the pressure transfer roller pair 15a, 15b after passing the last transfer position of the photosensitive drum 3, and a color image is formed and recorded. As the intermediate transfer member of No. 12, polyester, polyimide, urethane rubber, silicon rubber and the like are preferably used. Relationship and the relationship of H and R of T ₁ and T ₂ in the present figure is the same as in the previous examples. It should be noted that if this configuration is used to provide an observation window through which an image on the intermediate transfer body 12 can be directly observed, it is also possible to realize a color image display device.

The first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 7 can be widely applied to an electrophotographic image forming apparatus in general, and the writing means is not limited to a laser scanner. The present invention can also be applied to a device using an LED array, or a device using an ion current modulation charger known in JP-A-54-78134.

FIG. 8 shows still another embodiment of the present invention. The apparatus of the present embodiment is a color image forming apparatus in which the present invention is applied to a thermal transfer recording method using an ink having supercooling characteristics proposed by the present applicant in Japanese Patent Application Laid-Open No. Sho 62-53856.

In the figure, reference numeral 31 denotes an intermediate transfer drum for temporarily holding an image. Reference numeral 32 denotes an ink supply means for supplying a transfer ink layer to the surface of the drum 31.The ink supply means 32 has a supercooling property obtained by mixing a coloring agent such as a pigment with a supercooling substance such as unsaturated polyester. Supply. Reference numeral 33 denotes a heating belt that generates heat by energization for selectively melting the ink layer formed on the surface of the drum 31. 34
Is a recording head that causes the heat generating layer of the heat generating belt 33 to generate heat in accordance with image information, and is provided at a density of, for example, 16 pel / mm. The heating belt 33 includes a heating layer that generates Joule heat and a conductive layer, and the recording head 34 includes electrodes that can supply current to the heating layer in accordance with image information.

With the above configuration, the solidified ink layer is melted again, and information in a supercooled state is formed on the ink layer according to the image information. Then, the image information reaches the transfer position of the platen roller 35 in the supercooled state, and the continuous recording sheet 36
The supercooled ink is transferred to the printer, and image information is recorded. By repeating the above processing steps sequentially in three recording units, a color image is superimposed on the recording sheet 36 as a transfer sheet.

Also in this example, the time required for the _first recording head 34 to move from the image forming position to the second transfer position is T1, and the time required for the second recording head 34 'to move from the image forming position to the second transfer position is T1. and T _2, integers m, when the T ₃ as a recording time between pixels, the equation of _{m × T 3 ≒ T 1 -T} 2 is arranged the elements so as to establish, can prevent misregistration. The use of the fine adjustment screw 38 in order to satisfy the condition of this equation is the same as in the above embodiment. Reference numeral 37 denotes a fixing member with a long hole for fixing the recording heads 34, 34 ', 34 ".

Further, if the transfer position interval is H, the diameter of the driving roller 39 is R, and n is an integer, R or H may be determined so as to satisfy the following expression: n × π × R ≒ H.

FIG. 9 shows still another embodiment of the present invention. The apparatus of this embodiment is disclosed in Japanese Patent Application Nos. 61-175191 and 62-17.
No. 09, Japanese Patent Application Nos. 62-125973 and 62-198189, and the present invention is applied to an energization recording method using a fluid ink which has fluid film forming properties and is tackified by applying energy. Is a color image forming apparatus to which is applied.

In the figure, an ink transfer roll 41 is provided rotatably in the direction of arrow A while transferring the fluid ink 42 stored in the ink reservoir 43. The fluid ink 42 has fluid film-forming properties and does not have tackiness in a normal state, but has a property of having tackiness when a predetermined energy, for example, electric energy is applied. Therefore, when the ink transfer roll 41 rotates, the coating means 44 causes the surface of the ink transfer roll 41 to have a constant layer thickness, so that the arrow A
Transported in the direction.

The fluid ink 32 formed in a constant layer on the surface of the ink transfer roll 1 is converted into an electric energy by an energy applying means (energizing head) 45 controlled by a control means (not shown) into an image pattern image corresponding to the input image information. Is applied, and an ink image with tackiness is formed by the energy application.

The adhesive ink image comes into contact with the intermediate transfer body roll 46 rotating in the direction of arrow B in FIG.
Transferred to 46 surfaces. The image thus transferred is further transferred onto transfer paper 48, which is a continuous paper, with the help of the platen roller 47.

The color image is superimposed and formed on the transfer paper 48 by repeating the above processing steps sequentially in three recording units.

Now, the image forming position of the energizing head 45 which is an image recording unit on the upstream side in the present embodiment, the more time that the image to the transfer position on the downstream side moves When T _1, the movement time T ₁
Is the sum of the travel times TA, TB and TC indicated by arrows in the figure. That is, TA + TB + TC = T ₁ (3)

Further, when the time that the image from the image forming position of an image recording means on the downstream side conducting head 45 'to the transfer position to move to T _2, moving time indicated by an arrow in the movement time T ₂ are present FIG TD And TE. That is, TD + TE = T ₂ (4) Here, assuming that the inter-pixel recording time is T ₃ and m is an integer, if each element is arranged in an amount that satisfies the expression m × T ₃ ≒ T ₁ −T _2, a mistake will be made. Registration can be prevented. At this time, the position of the recording head 35 may be adjusted using the adjustment screw 49. The configuration of the adjusting screw portion is the same as in the first embodiment.

Also in this example, if the transfer position interval is H, the diameter of the drive roller 50 is R, and n is an integer, then R or H is determined so as to satisfy the formula of n × π × R ≒ H. Good.

In addition, as the above-mentioned fluid ink 42, an ink having a gel state in a broad sense that holds a solvent by a cross-linked structure substance,
Alternatively, an ink having a sludge state obtained by dispersing particles (having a particle size of preferably 0.1 to 100 μm, more preferably 1 to 20 μm) in a solvent having a relatively high viscosity (preferably 5000 cps or more) is preferably used. Inks having both properties of both the gel ink and the sludge ink are more preferably used. As a specific example of this ink, for example, Japanese Patent Application No.
No. 175191 or Japanese Patent Application No. 62-36904 are preferred.

When energy such as electricity is applied to the above-mentioned gel-like ink or sludge-like ink, the cross-linking structure of the gel-like ink or the arrangement state of the particles of the sludge-like ink changes. It is considered that the fluid ink has the tackiness according to the energy application. Further, when the ink 42 is coated on the ink transfer roller 41, the ink 42 has a property as a plastic body.On the contrary, after the energy is applied by the energy applying means 45, the ink 42 reaches the intermediate transfer roll 46. It preferably has the properties of an elastic body.

The above-mentioned inks 42 are mixed with colorants of different colors, respectively. Examples of such ink colorants suitably used in the present invention include the following dyes and pigments. These are used alone or in combination of two or more. The pigment or dye is used in an amount sufficient to highly color the ink and form a clear visible image.
For example, as a dye / pigment, in the case of a pigment, it is used in an amount of about 1% to 40% by weight of the total weight of the ink, but in the case of a dye, a substantially smaller amount, for example, 30% by weight or less. Used in

(A) Colorants for black include carbon black, magnetite, iron oxide, nigrosine dye, chrome yellow,
Ultramarine blue, Dupont oil red, methylene blue chloride, phthalocyanine blue and the like.

(B) colorants for magenta include 2,9-dimethyl-substituted quinacridone and anthraquinone dyes described as CI60710 in the Color Index, CI Dispersed Red 15, diazo dyes described as CI26050 in the Color Index, CI Solvent Red 19 and the like.

(C) Colorants for cyan include copper tetra-4 (octadecylsulfonamide) phthalocyanine, X-copper phthalocyanine pigment described as CI74160 in the Color Index, CI Pigment Blue, and CI69810 described in the Color Index. And special blue X-2137.

(D) As a colorant for yellow, 3,3-dichlorobenzidine acetoacetanilide which is dianilide yellow, a monoazo pigment described as CI12700 in the color index, CI Solvent Yellow 16, and HOLON in Color Intex Nitrophenylamine sulfonamide described as Yellow 6E / GLN, CI Dispersed Yellow 33, 2,5-dimethoxy-4-sulfonanilide phenyl-4'-chloro-2,5-dimethoxyacetoacetanilide, permanent Yellow GL
And the like.

As described above, according to the present invention, the method is not limited to a specific recording method as long as it has an image forming medium that temporarily holds an image, and can prevent misregistration and accurately perform multiple recording. . In the above description, 式
The symbol (nearly equal) is used, but the tolerance is as large as the drive roller is allowed due to processing tolerance. Also, T ₁ −T ₂ is not clearly defined,
On experience, ± 20% of T ₃ is allowed.

Next, in order to further facilitate understanding of the embodiment of the present invention, an example of transfer timing control at each transfer position described above will be described. Hereinafter, the case of the first embodiment shown in FIG. 1 will be described as a representative example. Although FIG. 1 shows an example using three color inks of cyan (C), magenta (M) and yellow (Y), a recording unit using black (BK) ink is added thereto. I do.

FIG. 10 shows an example of the configuration of the whole control circuit, where Y, M, C, and BK attached to each block are yellow, magenta, and magenta, respectively.
This indicates that the unit is for cyan and black. In FIG. 10, reference numeral 200 denotes the semiconductor laser 5 shown in FIG.
1. A laser drive circuit for driving 1; 201, a mirror drive circuit for rotationally driving the polygon mirror 52 shown in FIG. 3;
202 is a drum drive circuit for driving the drum motors of the drums 1, 2 and 3, 204 is a paper feed motor drive circuit for driving the paper feed motor, and 205 is a main drive motor for driving the main motor of the drive roller 14. Motor drive circuit, 206 is paper feed roller 5
7-2, a high-pressure source of the static eliminator 69 shown in FIG. 5, a high-pressure source 208 of the adsorption charger 63 shown in FIG. 209
Reference numeral 210 denotes a control circuit including a known microcomputer, and reference numeral 210 denotes a developing bias power supply of the developing device 59.

FIG. 11 and FIG. 12 are flowcharts showing a program for achieving the sequence control by the control circuit 209.

First, when the power is turned on, initialization of the microcomputer included in the control circuit 209 and setting of the interrupt condition are performed in steps 200 and 201. In step 200, for example, a stack pointer is set and an input / output device is assigned. In step 201, a jump address and an interrupt device at the time of interruption are assigned.
Next, since the laser drive circuit 200 has a temperature control function for controlling the temperature of the semiconductor laser 51,
After confirming that the temperature control has been completed by the signals of the signal lines 201 to 204 in 202 and step 203, the mirror driving circuit 201 is turned on by outputting a mirror driving signal to the signal lines 209 to 212 in step 204, and the polygon is turned on. The driving of the mirror 53 is started.

The following steps 235 and 236 detect the signals on the signal lines 205 to 208 to detect the operation state of the polygon mirror 53, and confirm that the rotation of the polygon mirror 53 has stabilized at a predetermined rotation speed. Steps 205 and 206 are functions for checking whether or not to start the subsequent sequence. In this embodiment, the transfer paper 11 is checked by the operator.
Check if the has been inserted into the device.

When the transfer paper 11 is inserted into the paper feed table 57-1, step 20 is executed.
7, the signal is output to signal lines 213 to 216 for rotationally driving the photosensitive drums 1, 2, 3, and 3 '(3' is not shown). Start rotation. The operations from step 207 to step 213 do not necessarily have to follow the order shown in FIG. 11, and may be performed in any order or simultaneously. Further, the steps may be performed while adjusting the time between the steps as necessary. In step 208, the inserted transfer paper 11
To the feed belt 12 driven by the main motor drive circuit 205.
Turns on by outputting a signal to 17. Step 20
Reference numeral 9 denotes a main motor driving circuit 205 for driving a main motor that moves a conveying belt 12 that conveys an image to a transfer sheet 11 while transferring the image to a paper output unit 67 by outputting a signal to a signal line 218. Turn on. In step 210, the cleaner 61 for cleaning the photosensitive drums 1, 2, 3, and 3 'is connected to the signal line 2.
It is turned on by outputting a signal to 19 to 222, and in steps 211 to 213, the primary charger 58, developing bias power supply 210, and static eliminator 69 necessary for the electrophotographic process are turned on.

By the way, the paper feed roller 57-
2 is a paper feed plunger 20 via a clutch (not shown).
6, the driving force of the paper feed motor is not transmitted to the paper feed roller 57-2 because the paper feed plunger 206 is still off as described later. Numeral 11 remains on the paper feed table 57-1. Although the operation of the transport belt 12 has already started by the operation of step 209, in order to feed the inserted transfer paper 11 to a specific position of the transport belt 12, for example, a position separated by a predetermined distance from the seam of the belt 12, Steps 214 and 215
, The position of the belt 12 is detected based on the output of the photo interrupter 65.

For example, after detecting a seam of the belt 12 in Steps 214 and 215, appropriate time adjustment is performed in Step 216 in order to feed the paper to a position separated by a predetermined distance, and then a signal line is processed in Step 218. By outputting a signal to 223, the above-mentioned paper feed plunger 206 is turned on, and paper is fed by rotating paper feed roller 57-2. Step 217 does not need to be performed between step 216 and step 218.
The transfer charger 60 may be turned on by outputting a signal to the signal lines 224 to 227.

In steps 205 to 218, the previous stage of the printing operation is completed, and thereafter, the vertical synchronizing signal V-SYN
C, actual operation of image printing according to image data input in synchronization with the horizontal synchronization signal H-SYNC signal is started. Since this interrupt utilizes a timer interrupt in this embodiment, a process for starting the interrupt timer is performed in step 219.

Now, there are three types of interrupt processing shown in FIG. 12 as (A), (B) and (C). The first interrupt processing (A) is interrupt processing 1 to 4, and controls the transfer chargers 60Y, 60M, 60C, and 60BK corresponding to the Y, M, C, and BK process units, respectively. Steps 220 to 222 show this interrupt processing. In a case where a conductive member is used as a material of the seam of the special portion of the transport belt 12, for example, the belt 12, for example, the seam of the belt 12, This operation is performed to prevent discharge of the transfer high-voltage current to the member. That is, when the conductive member comes near any one of the transfer chargers 60Y, 60M, 60C, and 60BK, the corresponding transfer charger off processing is started at step 220 so that the corresponding transfer charger is turned off at the same timing. The interrupt process is started by the timer set in step (1). Step 221 is as follows.
Adjust the time until passing through 0M, 60C, 60BK. In step 222, after the time adjustment performed in step 221, the turned off one of the transfer chargers 60Y, 60M, 60C, and 60BK is turned on again. In this interrupt processing, control is performed by outputting signals to the signal lines 224 to 227.

The second interrupt processing (B) is interrupt processing 5 to 8, and the developing units 59Y, 59Y, included in the Y, M, C, and BK process units, respectively.
59M, 59C, 59BK are controlled. Step 223 to Step 2
At 25, the developing device 59 is controlled so that development is performed only when the image to be transferred to the transfer paper is written on the photosensitive drums 1, 2, 3, 3 'by laser light. In this interrupt processing, control is performed by outputting signals to the signal lines 232 to 235.

The third interrupt processing (C) is an interrupt processing 9 in which post-processing is performed after one sheet is printed. Step 22
The order of 6 to step 234 is arbitrary and may be simultaneous. In the present embodiment, in consideration of the characteristics of the photosensitive belt drums 1, 2, 3, and 3 ', the transfer charger 60 is turned off in step 226, and the time is adjusted in step 227 to set the primary charger 58 in step 228.
Is off at Steps 229 to 234 turn off the static eliminator 69, turn off the developing bias 210, turn off the cleaner 61, turn off the main motor 205, turn off the sheet feeding motor 204, and turn off the drum motor 202, respectively.

Thereafter, each unit is in the ready state after step 236 in FIG. 11 is completed, and repeats steps 205 and 206 to wait for the next sheet feeding.

By the way, although the adsorption charger 63 has not been described in the present flowchart, the adsorption charger 63 is turned on before the sheet is fed in step 218, and turned off after the sheet is fed, so that the transfer sheet 11 is turned off. Can be sufficiently adsorbed to the transport belt 12. In this embodiment,
Although it has been described that the interruption processes 1 to 8 are performed by the timer interruption, the interruption may be performed by the photo interrupter 62, and the same as the main interruption process by the time monitoring means or the state detection of the photo interrupter 62. Processing can be performed.

[Effects of the Invention] As described above, according to the present invention, the image formed on the upstream image carrier is shifted from the image forming position on the upstream image carrier to the downstream image carrier. The time required for the image formed on the transfer material to move to the transfer position where the image is transferred onto the transfer material, and the image formed on the downstream image carrier is moved from the image formation position on the downstream image carrier to the transfer position. Since the plurality of image carriers are arranged so that the difference from the time required to move to the transfer position is substantially an integral multiple of the scanning period, the irradiation position of the laser beam in the sub-scanning direction is adjusted or irradiation is started. Even without performing various adjustment operations for correcting misregistration after assembling the image forming apparatus such as adjusting the timing, if the pixel is designed and manufactured according to the present invention, each pixel can be accurately overlapped on the transfer material. , Miss Regis The effect of eliminating the torsion and preventing the occurrence of hue shift due to moiré fringes is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an entire apparatus according to a first embodiment of the present invention, FIG. 2 is a plan view showing an enlarged part of FIG. 1 as viewed from a direction A, and FIG. 1 is a perspective view showing a configuration example of one image forming means, FIG. 4 is a cross-sectional view showing a detailed configuration of a sheet feeding side and a photosensitive drum portion in FIG. 1, and FIG. 5 is a sheet ejection in FIG. FIG. 6 is a cross-sectional view showing a detailed configuration of a side portion, FIG. 6 is a plan view schematically showing a pixel recording state on the transfer paper of FIG. 1, and FIG. 7 is a schematic configuration of an entire apparatus according to a second embodiment of the present invention. FIG. 8 is a schematic diagram showing a schematic configuration of an entire apparatus according to a third embodiment of the present invention. FIG. 9 is a schematic diagram showing a schematic configuration of an entire apparatus according to a fourth embodiment of the present invention. FIG. 10 is a block diagram showing a configuration example of a control circuit of the embodiment of FIG. 1, and FIGS. 11 and 12 are flowcharts showing an example of a control procedure of the controller of FIG. It is a door. 1,2,3 ... Photosensitive drum, 5,6,7 ... Laser scanner, 8,9,10 ... Raster line, 11,36,48 ... Transfer paper, 12 ... Conveyer belt, 14,39, 50 ... Driving roller, 15,16 ... Driving roller, 18,19,38,49 ... Fine adjustment screw, 21 ... Long hole, 31 ... Intermediate transfer drum, 32 ... Ink supply means, 33 ... … Heating belt, 34… Recording head, 41… Ink transfer roll, 42… Fluid ink, 43… Ink reservoir, 44… Coating means, 45… Application means, 46… Intermediate transfer roll, 209 ... Controller (control circuit).

Claims (5)

(57) [Claims] A plurality of images formed on each image carrier by periodically scanning in a main scanning direction on a plurality of independent image carriers are sequentially superimposed on a transfer material moving in a sub-scanning direction. An image forming apparatus for transferring an image formed on an upstream image carrier from an image forming position on the upstream image carrier to an image formed on a downstream image carrier on the transfer material. The difference between the time for moving to the transfer position where the image is transferred to the transfer position and the time for moving the image formed on the image carrier on the downstream side from the image forming position on the image carrier on the downstream side to the transfer position. An image forming apparatus, wherein the plurality of image carriers are arranged so as to be substantially an integral multiple of the scanning period. 2. The image forming apparatus according to claim 1, further comprising a plurality of position adjusting means for finely adjusting image forming positions on the plurality of image carriers. 3. An image forming apparatus according to claim 1, wherein said plurality of image carriers are periodically scanned by a light beam to form an image. 4. The image forming apparatus according to claim 1, wherein said plurality of image carriers are periodically scanned by an LED array to form an image. 5. The image forming apparatus according to claim 1, wherein the transfer material is a recording sheet conveyed by a conveyance belt moving in the sub-scanning direction.