JP2004240111A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep an image density constant regardless of an image forming speed in a color image forming apparatus having a plurality of image forming speeds. <P>SOLUTION: The color image forming apparatus having the plurality of image forming speeds includes: a cartridge incorporating a development unit; a means for storing, in the cartridge, initial data necessary for toner concentration control corresponding to the image forming speeds; and a means for reading the initial data and using it in the course of image formation. When the cartridge is shipped or installed, the initial data necessary for toner concentration control corresponding to the image forming speeds is determined according a special mode and it is stored in the cartridge. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, a color image is formed by forming an electrostatic latent image on an image carrier such as a photosensitive drum, developing the electrostatic latent image, and transferring the electrostatic latent image to a recording material, such as a color copying machine or a color printer. The present invention relates to a color image forming apparatus having a plurality of image forming speeds.
[0002]
[Prior art]
2. Description of the Related Art In an image processing apparatus that forms an image using a two-component developer composed of a toner and a carrier, toner is replenished by comparing a toner density signal at the time of image formation with a reference toner density, and the toner density is kept constant. Control is being performed. At this time, an electric signal from a sensor for detecting the toner density is used as a toner density signal and a reference toner density signal, and the initial toner density signal set in the special mode when the cartridge is shipped or the cartridge is installed. The control voltage value and the reference toner density value are read out from the EEPROM in the cartridge and used at the time of image formation.
[0003]
[Problems to be solved by the invention]
However, since the control voltage value of the initial toner density signal and the reference toner density value stored in the EEPROM are data corresponding to a specific image forming speed, an image forming apparatus having a plurality of image forming speeds has Changes, the toner stirring speed in the developing unit changes accordingly, and the toner level signal changes by changing the height of the developer surface across the toner density sensor in the developing unit, affecting the image density. There was a problem. Therefore, an object of the present invention is to determine initial data necessary for toner density control corresponding to a plurality of image forming speeds in a special mode at the time of shipping a cartridge or installing a cartridge, and store the initial data in the cartridge. It is possible to provide a color image forming apparatus that can use an appropriate value depending on the image forming speed and can keep the image density constant regardless of the image forming speed.
[0004]
[Means for Solving the Problems]
The above object is achieved by a color image forming apparatus according to the present invention. In summary, according to the present invention, in a color image forming apparatus having a plurality of image forming speeds, a cartridge including a developing device and initial data necessary for toner density control corresponding to the plurality of image forming speeds are stored in the cartridge. Means for reading out initial data necessary for the toner density control and using the same during image formation.When the cartridge is shipped or when the cartridge is installed, the toner density control corresponding to the plurality of image forming speeds is performed in a special mode. A color image forming apparatus characterized in that necessary initial data is determined and stored in a cartridge.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the color image forming apparatus according to the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a configuration diagram of a color image forming apparatus according to a first embodiment of the present invention. This color image forming apparatus includes a color reader unit and a color printer unit.
[0006]
[Configuration of color reader unit]
In FIG. 1, a document table glass (platen) 301 is provided horizontally above a color reader unit, and a document feeder (DF) 302 is provided thereon. Note that there is also a configuration in which a mirror pressure plate (not shown) is mounted instead of the document feeder 302. Inside the first carriage 314, light sources 303 and 304, which are halogen lamps, reflectors 305 and 306 for condensing the light from the light sources 303 and 304 on the document, and a mirror 307 for reflecting the light reflected from or projected from the document. It is installed. The second carriage 315 is provided with mirrors 308 and 309 for further condensing the reflected light from the mirror 307 on the CCD 101.
[0007]
Further, a substrate 311, on which the CCD 101 is mounted, an element other than the CCD 101 shown in FIG. 2, an image processing unit 312 including the binary conversion unit 201, delay units 202, 203, 204, and 205 shown in FIG. And the like (I / F) unit 313.
[0008]
Note that the first carriage 314 is moved at a speed V, and the second carriage 315 is moved at a speed V / 2, by mechanically moving the CCD 101 by a driving unit 316 in a direction perpendicular to the electrical scanning (main scanning) direction. Then, the entire surface of the document is scanned (sub-scan).
FIG. 2 is a block diagram showing a detailed configuration of the digital image processing unit 312.
[0009]
In the figure, a document on a platen glass reflects light from light sources 303 and 304, and the reflected light is guided to a CCD 101 and converted into an electric signal. In the case where the CCD 101 is a color sensor, even if RGB color filters are mounted in-line on a one-line CCD in the order of RGB, the CCD 101 is a three-line CCD in which R filters, G filters, and B filters are arranged for each CCD. The filter may be on-chip, or the filter may be configured differently from the CCD.
[0010]
Then, the electric signal (analog image signal) is input to the image processing unit 312, and the clamp & Amp. The sample / hold (S / H) is performed by the & S / H & A / D unit 102, the dark level of the analog image signal is clamped to the reference potential, and is amplified to a predetermined amount (the above processing order is not limited to the notation order). It is D-converted and converted into, for example, a digital signal of 8 bits for each of RGB.
[0011]
The RGB signal is subjected to shading correction and black correction by the shading unit 103, and then by the connection & MTF correction & document detection unit 104, when the CCD 101 is a three-line CCD, the connection processing differs in the reading position between lines. The amount of delay for each line is adjusted according to the reading speed, and the signal timing is corrected so that the reading positions of the three lines are the same. The MTF correction changes because the reading MTF changes depending on the reading speed and the magnification. And the original detection recognizes the original size on the original platen glass.
[0012]
The input masking unit 105 corrects the spectral characteristics of the CCD 101 and the spectral characteristics of the light sources 303 and 304 and the reflectors 305 and 306 on the digital signal whose read position timing has been corrected. The output of the input masking unit 105 is input to a selector 106 that can be switched with an external I / F signal.
[0013]
The signal output from the selector 106 is input to the color space compression & background removal & LOG conversion unit 107 and background removal unit 115. After the signal input to the background removal unit 115 is removed from the background, the signal is input to a black character determination unit 116 that determines whether or not the document is a black character in the document, and a black character signal is generated from the document. The color space compression & background removal & LOG conversion unit 107, to which the output of the other selector 106 is input, determines whether the read image signal is within the range that can be reproduced by the printer and enters the color space compression. If it does not, the correction is made so that the image signal falls within the range that can be reproduced by the printer. Then, a background removal process is performed, and the RGB signals are converted into CMY signals by LOG conversion.
[0014]
The timing of the output signal of the color space compression & background removal & LOG conversion unit 107 is adjusted by a delay 108 to correct the timing and the signal generated by the black character determination unit 116. The two types of signals are subjected to moiré removal by the moiré removal unit 109, and then subjected to scaling processing in the main scanning direction by the scaling processing unit 110.
[0015]
In the UCR & masking & black character reflection unit 111, the signals processed by the scaling processing unit 110 are converted into CMYK signals by the UCR processing of the CMY signals, corrected by the masking processing unit into signals which are present at the output of the printer, and black characters are processed. The determination signal generated by the determination unit 116 is fed back to the CMYK signal.
[0016]
The signal processed by the UCR & masking & black character reflection unit 111 is subjected to density adjustment by the γ correction unit 112 and then subjected to smoothing or edge processing by the filter unit 113. The signal processed as described above is converted from an 8-bit multi-level signal into a binary signal by the binary converter 201 shown in FIG. This conversion method may be any one of the improved dither method, error diffusion method and error diffusion method.
[0017]
[Configuration of Color Printer]
In FIG. 1, a Y image forming unit 317, an M image forming unit 318, a C image forming unit 319, and a K image forming unit 320 include photosensitive drums 342, 343, 344, 345, and chargers 321, 324, 327, 330, respectively. , LED units 210, 211, 212, 213, developing units 322, 325, 328, 331, and auxiliary charging units 360, 361, 362, 363. The chargers 321, 324, 327, and 330 have charging sleeves 370, 371, 372, and 373, respectively, and the developing devices 322, 325, 328, and 331 have developing sleeves 345, 346, 347, and 348, respectively. .
[0018]
Since the respective configurations are the same, the Y image forming unit 317 will be described in detail, and the description of the other image forming units will be omitted.
[0019]
The Y image forming unit 317 is provided with a photosensitive drum 342, around which a charger 321, an LED unit 210, a developing unit 322, an auxiliary charger 360, and the like are arranged. Here, the photosensitive drum 342, the charger 321 and the developing device 322 form an integrated cartridge 390.
[0020]
In these operations, first, the photosensitive drum is charged by the auxiliary charger 360 and the charger 321. Next, a latent image is formed on the surface of the photosensitive drum by the light from the LED array 210, and is developed by the developing device 322 to form a toner image.
[0021]
The developing device 322 includes a sleeve 345 for applying a developing bias to perform development. A transfer belt 323 is disposed below the developing device 322 in the figure with the transfer belt 333 interposed therebetween, and discharges electricity from the back of the transfer belt 333 to transfer the toner image on the photosensitive drum 342 to the recording paper on the transfer belt 333. Transfer to
[0022]
After the transfer, the toner 503 remaining on the photosensitive drum 342 is once taken into the charger 321 to change its electrostatic characteristics and return it to the photosensitive drum 342 again, and the developing unit 322 collects and reuses it. .
[0023]
Next, a procedure for forming an image on a recording paper or the like will be described. The recording paper and the like stored in the cassettes 340 and 341 are supplied to the transfer belt 333 moved by the paper feed rollers 336 and 337 one by one by the pickup rollers 338 and 339. The transfer belt 333 is disposed below the Y image forming unit 317, the M image forming unit 318, the C image forming unit 319, and the K image forming unit 320, and is driven by a transfer belt roller 348.
[0024]
The leading edge of the recording paper fed to the transfer belt 333 is detected by a paper leading edge sensor 347. The detection signal of the paper leading edge sensor is sent from the printer unit to the color reader unit, and is used as a sub-scan synchronization signal when a video signal is sent from the color reader unit to the printer unit.
[0025]
Thereafter, the recording paper or the like is conveyed by the transfer belt 333, and a toner image is formed on the surface of the image forming units 317 to 320 in the order of YMCK.
[0026]
The recording paper or the like that has passed through the K image forming unit 320 is separated from the transfer belt 333 after the charge is removed by the charge removing charger 349 to facilitate separation from the transfer belt 333. A peeling charger 350 is provided adjacent to the neutralizing charger 349 to prevent image disturbance due to peeling discharge when the recording paper or the like is separated from the transfer belt 333.
[0027]
The separated recording paper or the like is charged by the pre-fixing chargers 351 and 352 and then discharged after the toner image is heat-fixed by the fixing unit 334 in order to compensate for the toner adsorption force and prevent image disturbance. The paper is discharged to the paper tray 335. Further, the transfer belt 333 is neutralized by the internal / external static eliminator 353.
[0028]
The speed of the above image forming operation differs depending on the type of recording paper, and is normal speed, 1/2 speed, and 1/4 speed for plain paper, thick paper, and OHP, respectively.
[0029]
Next, a method of correcting and using data necessary for toner density control read from the EEPROM, which is a characteristic part of the present invention, according to the image forming speed will be described in detail.
[0030]
First, FIG. 4 shows a configuration of the developing device in the cartridge. The toner supplied from the toner supply port 42 circulates in the direction of the arrow in the drawing by the rotation of the stirring screw 41. When a developing bias is applied, the developing sleeve 43 is caused to fly to the image carrier by rotation. The toner density detection sensor 40 converts the toner density in the developing device into an electric signal, and this signal is input as a toner density signal 45 to a CPU in the apparatus main body. Further, the toner density signal 45 is variable by a control voltage 44 from the apparatus main body.
[0031]
The rotation speed of the stirring screw 41 corresponds to the image forming speed. When the rotation speed is low, the developer surface crossing the toner concentration detection sensor 40 is higher than that at the normal speed. The value of the toner density signal 45 differs depending on the image forming speed.
[0032]
Next, an initial setting method of the control voltage value of the toner density signal and the reference toner density value will be described with reference to the flowchart of FIG. First, the rotation speed is determined in S50, the stirring screw and the developing sleeve are rotated for one minute in S51, and the developing bias AC component is applied in S52. Next, in S53, the control voltage is automatically adjusted so that the toner density signal becomes 2.5V ± 0.15V. In step S54, the toner density signal is sampled 10 times at intervals of 20 ms, and the average value is determined as the reference toner density value. In step S55, the determined control voltage value and reference toner density value are written to the EEPROM in the cartridge. Here, these data are written in an area corresponding to the rotation speed. Then, the rotation of the stirring screw and the developing sleeve is stopped in S56, and the developing bias AC component is turned off in S57. In S58, it is next determined whether or not to take in the initial data at another rotation speed, and when it is to be executed at another rotation speed, the process shifts to S50, and at normal speed, 1/2 speed, 1/4 speed. If the setting of has been completed, the processing ends. These processes are the same for all color cartridges, and are executed by the following method when the cartridge is shipped or installed.
[0033]
FIG. 6 shows an operation unit of the color image forming apparatus of the present embodiment. A touch panel display 1001 normally displays the number of copies, a selected paper size, a magnification, and a copy density. A reset key 1002 returns the copy mode to the standard mode. A start key 1003 starts a copy operation. A stop key 1004 interrupts the copy operation. A clear key 1005 returns the copy mode to the standard mode. 1006 is a numeric keypad for setting the number of copies.
[0034]
By simultaneously pressing the * key on the operation unit and the numeric keys 2 and 8 in FIG. 6, a special mode screen shown in FIG. 7 is displayed on the touch panel 1001. The initial setting is executed by pressing a key A indicating the initial setting of the toner density control in the special mode screen. Pressing the cancel key returns to the normal screen.
[0035]
【The invention's effect】
As described above, according to the present invention, when a cartridge is shipped or a cartridge is installed, initial data necessary for toner density control corresponding to a plurality of image forming speeds is determined in a special mode and stored in the cartridge, thereby enabling printing. It is possible to provide a color image forming apparatus that can use an appropriate value depending on the image forming speed and can keep the image density constant regardless of the image forming speed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a color image forming apparatus according to an embodiment.
FIG. 2 is a block diagram illustrating a configuration of a digital image processing unit according to the embodiment.
FIG. 3 is a block diagram illustrating a configuration of an LED driving unit according to the embodiment.
FIG. 4 is a configuration diagram of a developing device according to the embodiment.
FIG. 5 is a flowchart illustrating initial settings of toner density control according to the embodiment.
FIG. 6 is a diagram showing an operation unit according to the embodiment.
FIG. 7 is a view showing a special mode screen of the embodiment.

Claims (4)

In a color image forming apparatus having a plurality of image forming speeds,
A cartridge including a developing device;
Means for storing initial data necessary for toner density control corresponding to a plurality of image forming speeds in a cartridge,
Means for reading out initial data necessary for the toner density control and using the data during image formation. The initial mode necessary for the toner density control corresponding to the plurality of image forming speeds in a special mode at the time of shipping the cartridge or installing the cartridge is provided. A color image forming apparatus wherein data is determined and stored in a cartridge. 2. The color image forming apparatus according to claim 1, wherein the stored initial data necessary for toner density control according to the plurality of image forming speeds is a control voltage value of a toner density signal and a reference toner density value. 2. The color image forming apparatus according to claim 1, wherein a toner stirring speed of said developing device corresponds to an image forming speed. 2. The color image forming apparatus according to claim 1, wherein said image forming speed is one of three types: normal speed, 1/2 speed, and 1/4 speed.

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