JP5568903B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  According to the transfer separation process in the image forming apparatus, the toner image formed on the image carrier is transferred to the paper, and the paper in close contact with the image carrier is separated from the image carrier. The ease of separation is greatly affected by the printing rate.

When the printing rate is high, it means that a large amount of toner is interposed between the image carrier and the paper. Therefore, the electrostatic adsorption force between the image carrier and the paper is weak and easily separated.
On the other hand, when the printing rate is small, only a small amount of toner is interposed between the image carrier and the paper, so that the electrostatic adsorption force between the image carrier and the paper is difficult to separate strongly.

  According to Patent Document 1, a technique for performing control related to transfer separation based on a printing rate is disclosed (see Patent Document 1).

JP 2000-89614 A

However, according to the technique of Patent Document 1, transfer separation control based on the calculated printing rate is not performed when printing the image data with the calculated printing rate. The calculated printing rate is used in control at the time of printing after the image data for which the printing rate is calculated.
That is, with the technique of Patent Document 1, it is impossible to control transfer separation in real time.

  An object of the present invention is to provide an image forming apparatus capable of calculating a printing rate in a processing stage prior to temporarily storing input image data in an image memory.

According to the present invention,
An input unit for inputting image data;
A print counter for counting the number of print pixels on each of the four sides of the input image data;
An image memory for temporarily storing the input image data before printing processing;
A transfer device for transferring a toner image developed on the image carrier based on the input image data to the paper by applying a transfer electric field to the paper;
A separation device that separates the paper on which the toner image has been transferred from the image carrier by applying a separation electric field to the paper;
A control unit;
An image forming apparatus comprising:
The control unit prints the four sides of the input image data based on the number of print pixels counted by the print counter before the input image data is temporarily stored in the image memory. Are calculated and stored in the image memory, and the transfer device or the printing device based on the information of the printing rate of the side corresponding to the leading end portion in the paper feeding direction in the printing process among the calculated printing rates of the four sides. An image forming apparatus for controlling a transfer electric field or a separation electric field applied to the sheet by the separation device is provided.

According to the present invention, the print ratio of the four sides of the image data can be calculated before the input image data is temporarily stored in the image memory. Therefore, even when the tip portion is replaced. The transfer separation current can be controlled in real time.
Further, even when a plurality of image data are collectively printed as one image data, the transfer separation current can be controlled in real time.

1 is an overall configuration diagram of an image forming apparatus. 1 is an overall configuration diagram of an image forming unit. 1 is a functional configuration diagram of an image forming apparatus. It is an internal block diagram of a printing counter. It is a figure which shows the timing chart of a VV signal and an HV signal. It is an internal block diagram of a print count block. It is a flowchart of the whole process. It is a flowchart of a transfer current value calculation process. It is a flowchart of a printing rate calculation process. It is a flowchart of the 1st process calculation. It is a flowchart of the 2nd process calculation. It is a conceptual diagram of the whole process.

  The configuration and operation of the image forming apparatus in this embodiment will be described in detail with reference to the drawings. This embodiment is only an example of the present invention, and the present invention is not limited to this.

FIG. 1 shows the overall configuration of the image forming apparatus 100.
The image forming apparatus 100 includes an automatic document feeder 10, a scanner unit 20, an image forming unit 30, and a paper feeding unit 40.

The automatic document conveyance unit 10 conveys the document D placed on the document placement tray one by one to a predetermined conveyance path.
The scanner unit 20 irradiates the conveyed document D with a light source and receives reflected light reflected from the document D. The scanner unit 20 converts the received optical signal into an electrical signal (image data).

The image forming unit 30 forms (prints) an image on the paper P based on the image data.
The paper feed unit 40 stores a plurality of types of paper P in a tray, and feeds the paper P to the image forming unit 30 through a predetermined transport path.

FIG. 2 shows the overall configuration of the image forming unit 30.
The image forming unit 30 includes a drum-shaped photoconductor 31 that functions as an image carrier. Around the photoconductor 31, a charging device 32, an exposure device 33, a developing device 34, a transfer device 35, a separation device 36, and a separation claw 37, a cleaning device 38 and the like. Note that the image forming unit 30 includes a fixing device 39 that pressurizes and heats the image transferred onto the paper P, but is not illustrated here.

  The charging device 32 uniformly charges the surface of the photoconductor 31, and the exposure device 33 exposes the photoconductor 31 based on the image data to form an electrostatic latent image. The developing device 34 develops the electrostatic latent image formed on the photoreceptor 31 as a toner image.

The transfer device 35 applies a charge having a polarity opposite to that charged on the toner to the sheet P to generate a transfer electric field, and electrostatically attracts and transfers the toner image from the photoreceptor 31 to the sheet P.
The current supplied to the transfer device 35 when the transfer electric field is generated is called a transfer current.

The separation device 36 adds a charge having a reverse polarity to that at the time of transfer to generate a separation electric field, weakens the electrostatic adsorption force, and separates the sheet P from the photoreceptor 31.
The current supplied to the separation device 36 when the separation electric field is generated is called separation current.

  The separation claw 37 physically contacts the surface of the photoconductor 31 and separates the paper P from the photoconductor 31 when the paper P is not separated from the photoconductor 31 even after the separation process by the separation device 36.

  The cleaning device 38 removes residual toner from the photoreceptor 31 with a brush, a blade, or the like.

The control unit 1 controls operations of the transfer device 35, the separation device 36, and the separation claw 37.
Specifically, the control unit 1 controls the transfer current value or the separation current value to drive the separation claw 37 when necessary.

FIG. 3 shows a functional configuration of the image forming apparatus 100.
The control unit 1 includes a CPU, RAM, ROM, and the like (not shown).
The CPU performs various calculations in cooperation with various programs stored in the ROM or various data expanded in the RAM, and controls the operation of each unit shown in FIG.

The print counter 5 counts the number of pixels printed out of the total number of pixels of the image data and the number of pixels in a predetermined range (hereinafter, “number of print pixels”) as a sample. Here, a predetermined range will be described as an image leading end portion.
The print counter 5 outputs information on the counted number of pixels to the control unit 1. Note that the printing rate of the leading edge of the image is calculated by (printing rate of the leading edge of the image) = (number of printing pixels) / (total number of pixels).

FIG. 4A shows the internal configuration of the print counter 5.
The print counter 5 includes five print count blocks 51 to 55.
The four print count blocks 51 to 54 count the number of print pixels on the four sides in consideration of the fact that the leading edge of the image is replaced when the rotation process is performed.
The remaining print count block 55 counts the total number of pixels of the image data in order to measure the print rate.

  The print count blocks 51 to 55 receive a sub-scanning direction synchronization signal (VV signal), a main scanning direction synchronization signal (HV signal), a clock signal (CLK signal), a CPU I / F signal, and image data.

FIG. 4B shows a timing chart of the VV signal and the HV signal.
Vset1 and Vset2 indicate signals in an arbitrary period in the sub-scanning direction, and indicate an image effective period in the traveling direction of the paper P (sub-scanning direction).
Hset1 and Hset2 indicate signals in an arbitrary period in the main scanning direction, and indicate an image effective period in a direction (main scanning direction) perpendicular to the traveling direction of the paper P.
The oblique broken line L indicates that the scale is different between the VV signal and the HV signal.

  When the print count of the image tip 10 mm is performed, the control unit 1 sets Vset1 = 10 mm. In this case, Vset2 = Hset1 = Hset2 = 0 mm is set.

FIG. 4C shows the internal configuration of the print count block 51.
The print count block 51 includes a timing generation unit 511, a counter 512, and a register 513. The counter 512 counts the total number of pixels of the image data and the number of print pixels based on the timing signal output from the timing generation unit 511 and outputs the counted number to the register 513.

  Returning to FIG. 3, the scanner unit 20 includes a CCD (Charge Coupled Device) 21, a reading system image processing unit 22, a color conversion processing unit 23, and the like.

The CCD 21 reads analog image data from the document D, and outputs the read image data to the reading system image processing unit 22.

  The reading system image processing unit 22 performs A / D conversion or the like on the image data to generate RGB image data, and outputs the generated RGB image data to the color conversion processing unit 23.

  The color conversion processing unit 23 converts the RGB image data into YMCK image data, and outputs the converted YMCK image data to the image memory 2.

The printer controller 60 includes an image development unit 61, a color conversion unit 62, a gradation conversion unit 63, and the like.
Further, the printer controller 60 inputs PDL (Page Description Language) data generated by an external PC (not shown).

  The image developing unit 61 develops the input PDL data in a RAM (not shown) and rasterizes it into RGB image data.

  The color conversion unit 62 converts rasterized RGB image data into YMCK image data.

  The gradation conversion unit 63 performs gradation conversion processing on the YMCK image data, and outputs the YMCK image data subjected to the gradation conversion processing to the image memory 2.

  The image memory 2 is configured by a volatile memory (DRAM; Dynamic Random Access Memory), and temporarily stores image data before printing processing.

  The image processing unit 3 performs various image processing such as compression processing, expansion processing, and screen processing on the image data, and outputs the image processed image data to the writing system processing unit 4.

  The writing system processing unit 4 performs writing processing such as reduction processing, enlargement processing, and rotation processing on the image data, and then outputs the image data to the image forming unit 30.

  The image forming unit 30 receives image data and prints it based on a control signal from the control unit 1. The printing process is as described in the description of FIG.

The overall process will be described with reference to FIG.
The controller 1 sets image processing parameters for the input image data (step S21 ).
The image processing parameters set here include parameters relating to image editing such as screen processing and aggregation.
The controller 1 performs a process for calculating the transfer current value (step S22 ).

With reference to FIG. 6, a process for calculating a transfer current value will be described.
The control unit 1 determines whether there is aggregation in the image processing parameters set in step S21 of FIG. 5 (step S11).
Aggregation refers to a process of printing a plurality of image data as a single image data. The number of images formed on one sheet increases as the image data is collected, and the printing rate increases.

When there is aggregation (step S11; Y), the control unit 1 calculates the printing rate of the leading end portion of the aggregated image data or the overall printing rate of the aggregated image data (step S12 ).

  Similarly, when the printing rate varies due to image processing other than aggregation, for example, processing such as overlay or overwriting, the control unit 1 calculates the printing rate of the image data after image processing.

When there is no aggregation (step S11; N), the control unit 1 calculates the printing rate of the leading end portion of the current image data or the entire printing rate of the current image data (step S13 ).

  The printing rate of the “tip portion” of the image data refers to the printing rate of a predetermined leading end portion (for example, a portion from the leading end to 10 mm toward the inside of the image data) in the traveling direction of the paper P.

With reference to FIG. 7, a process for calculating the printing rate will be described.
The controller 1 uses the print counter 5 to count the number of pixels at the front end portion of the image data or the total number of pixels as a sample (step S21).

  Here, the control unit 1 sets the number of pixels on the four sides of the image data as a sample in consideration of the fact that the leading edge and the trailing edge of the image data may be switched by rotation processing.

  The “four-side portion” here is a four-side portion that can be a tip portion, and is a portion from the end of each side to 10 mm toward the inside of the image data.

The controller 1 uses the print counter 5 to count the number of print pixels at the leading end of the image data or the total number of print pixels (step S22).
As described above, the number of print pixels at the tip is counted for four sides.

  When there are a plurality of input image data, the control unit 1 determines whether or not acquisition of all the image data has been completed (step S23).

If not completed (step S23; N), the control unit 1 stands by.
When the process is completed (step S23; Y), the control unit 1 calculates the print rate of the front end portion of the image data and the overall print rate based on the number of pixels counted as a sample by the print counter 5 and the number of print pixels. (Step S24).

Here, the control unit 1 calculates the printing rate as (printing rate) = (number of printing pixels) / (number of counted pixels), but is not limited thereto. For example, it may be simply (print rate) = (number of print pixels) or (print rate) = (number of print pixels) / (predetermined coefficient).
The print rate is calculated by calculating the ratio of the number of print pixels (the number of ON images) to the total number of pixels based on the binarized image data before image processing, but based on the image data after image processing. The detailed printing rate may be calculated.

The control unit 1 writes the calculated printing rate of the leading end portion and the entire printing rate in the header of the image data (step S25), and ends the printing rate calculation process.
Returning to FIG. 6 , the control unit 1 performs a process calculation (step S14).

The first process calculation will be described with reference to FIG.
In the first process calculation, the control unit 1 sets a transfer current value.

The control unit 1 determines whether or not the printing rate of the tip portion is lower than a predetermined value (step S31).
When the printing rate of the front end portion is low (step S31; Y), the control unit 1 lowers the transfer current value of the front end portion to set the separation priority (step S32), and ends the first process calculation.

  When the printing rate of the tip portion is not low (step S31; N), the control unit 1 determines whether or not the printing rate of the tip portion is higher than a predetermined value (step S33).

  When the printing rate of the leading end portion is not high (step S33; N), the control unit 1 maintains the current state of the transfer current value at the leading end portion (step S34), and ends the first process calculation.

  When the printing rate of the leading end portion is high (step S33; Y), the control unit 1 increases the transfer current value of the leading end portion to set transferability priority (step S35), and ends the first process calculation.

The second process calculation will be described with reference to FIG.
The control unit 1 determines whether or not the printing rate at the tip portion is lower than a predetermined value (step S41).
When the printing rate of the front end portion is low (step S41; Y), the control unit 1 performs a setting for bringing the separation claw 37 into contact with the photosensitive member 31 (step S42), and ends the second process calculation.

  When the printing rate of the leading end portion is not low (step S41; N), the control unit 1 performs setting so that the separation claw 37 does not contact the photoconductor 31 (step S43), and ends the second process calculation.

Returning to FIG. 5, the control unit 1 performs a printing process with the set transfer current value (step S23 ), and ends the entire process.

FIG. 10 shows a conceptual diagram of the entire process.
The scanner unit 20 or the printer controller 60 inputs the first page of image data, the second page of image data, the third page of image data,.

  The RAM of the control unit 1 stores information on the calculated printing rate when input of each image data is completed or before each image data is temporarily stored in the image memory 2.

  The image memory 2 temporarily stores image data that has been subjected to compression processing after the printing rate is calculated.

The image forming unit 30 performs a printing process based on the image data subjected to the decompression process or the like.
The transfer device 35 switches the transfer current value when the leading end portion of the image data is printed in synchronization with the printing process.

  As described above, according to the present embodiment, since the printing rate can be calculated before the image data is temporarily stored in the image memory 2, the transfer separation current can be controlled in real time.

  Further, it is possible to store the calculated printing rate information in the header of the image data, and to control the transfer separation current based on the printing rate information stored in the header during printing. Even when the input order of image data and the printing order are different, it is possible to appropriately control the transfer separation current.

  Also, when the image data undergoes image processing, the print rate changes greatly, the print rate of the image data after image processing is calculated, and the transfer separation current is controlled based on the calculated print rate information. Can do.

Further, since the ease of separation largely depends on the electrostatic attraction force of the leading end portion of the paper P, only the printing rate of the leading end portion of the image data may be calculated. Since it is not necessary to use the total number of pixels of the image data as a sample, the printing rate calculation process can be performed quickly.

In addition, when the image data is rotated, the leading edge and the trailing edge (or the leading edge and the other three sides) are interchanged, so that the print rate of the four sides of the image data is calculated in advance. It is good. Even after the rotation processing, the transfer separation current can be controlled based on the printing rate at the leading end of the image data.

  Further, it is possible to control whether or not the separation claw 37 is brought into contact with the photosensitive member 31 based on the calculated printing rate. Since it is not necessary to contact the separation claw 37 unnecessarily, damage to the photoreceptor 31 can be minimized.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 10 Automatic document conveyance part 20 Scanner part 30 Image forming part 31 Photoconductor 32 Charging apparatus 33 Exposure apparatus 34 Development apparatus 35 Transfer apparatus 36 Separation apparatus 37 Separation claw 38 Cleaning apparatus 39 Fixing apparatus 40 Paper feed part 1 Control part 2 Image memory 3 Image processing unit 4 Writing system processing unit 5 Print counter

Claims (6)

An input unit for inputting image data;
A print counter for counting the number of print pixels on each of the four sides of the input image data;
An image memory for temporarily storing the input image data before printing processing;
A transfer device for transferring a toner image developed on the image carrier based on the input image data to the paper by applying a transfer electric field to the paper;
A separation device that separates the paper on which the toner image has been transferred from the image carrier by applying a separation electric field to the paper;
A control unit;
An image forming apparatus comprising:
The control unit prints the four sides of the input image data based on the number of print pixels counted by the print counter before the input image data is temporarily stored in the image memory. Are calculated and stored in the image memory, and the transfer device or the printing device based on the information of the printing rate of the side corresponding to the leading end portion in the paper feeding direction in the printing process among the calculated printing rates of the four sides. An image forming apparatus that controls a transfer electric field or a separation electric field applied to the sheet by the separation device. An input unit for inputting image data;
A setting unit for setting an aggregation process for printing a plurality of image data as a single image data;
A print counter for counting the number of print pixels on each of the four sides of the image data aggregated according to the setting of the setting unit;
An image memory for temporarily storing the image data aggregated according to the setting of the setting unit before the print processing;
A transfer device that transfers a toner image developed on the image carrier to the paper based on the image data aggregated according to the setting of the setting unit by applying a transfer electric field to the paper;
A separation device that separates the paper on which the toner image has been transferred from the image carrier by applying a separation electric field to the paper;
A control unit;
An image forming apparatus comprising:
The control unit sets the setting unit based on the number of print pixels counted by the print counter before the image data aggregated according to the setting of the setting unit is temporarily stored in the image memory. The print ratios of the four sides of the image data aggregated according to each are calculated and stored in the image memory, and correspond to the leading edge portion in the paper feeding direction in the printing process among the calculated print ratios of the four sides. An image forming apparatus that controls a transfer electric field or a separation electric field applied to the sheet by the transfer device or the separation device based on information on a printing rate of a side to be printed . The control unit stores the printing rate information in a header of the image data, and based on the stored printing rate information, a transfer electric field or separation applied to the paper by the transfer device or the separation device. The image forming apparatus according to claim 1, wherein the image forming apparatus controls an electric field. When the printing rate of the image data fluctuates before and after image processing, the control unit is applied to the paper by the transfer device or the separation device based on information on the printing rate of the image data after image processing. The image forming apparatus according to claim 1, wherein a transfer electric field or a separation electric field is controlled.   When the image data is rotated, the control unit uses the transfer device or the separation device based on the printing rate information of the tip portion after the rotation processing of the calculated printing rates of the four sides. The image forming apparatus according to claim 1, wherein a transfer electric field or a separation electric field applied to the paper is controlled. A separation claw is provided on the downstream side in the rotation direction of the image carrier from the separation device,
The image forming apparatus according to claim 1 , wherein the control unit controls driving of the separation claw based on the printing rate information.

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