JP2012236330A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimally suppress to an image quality degradation due to the light quantity non-uniformity of an exposure device without expanding the band of an exposure control circuit and a main processor.SOLUTION: Provided is an image forming apparatus having an LED head, which corrects the light quantity of the LED head by transmitting LED light quantity correction data to an exposure control means. The apparatus includes: a priority determination means 321 that partitions the light quantity correction data according to a predesignated partition and determines a transmission priority of the partitioned data; and a transmission/print control means 322 that transmits the partitioned data to the exposure control means, stops the data transmission under conditions of the detection of image formation start time; and conducts a transmission control for starting the image formation.

Description

  The present invention relates to an image forming apparatus having an exposure apparatus provided with a writing light source such as an LED (Light Emitting Diode) array and an image forming method in the image forming apparatus.

For example, an LED array is used as a writing light source in the image forming apparatus. When the LED array undergoes deterioration over time, a light amount decreases due to the installation environment of the device, or a change in the light amount due to a change in the installation environment (such as a high temperature environment) of the device, the image quality deteriorates due to the unevenness of the light amount.
Therefore, in order to prevent this, conventionally, the light amount correction value of the LED array is changed by transmitting light amount correction data from the main processor (generally CPU) to the control circuit of the LED head (patent). Reference 1).

  Data for correcting the amount of light (hereinafter referred to as light amount correction data) is assigned to each LED (light emitting element), and therefore the data size increases when the number of LEDs is large. On the other hand, in the bandwidth between the control circuit of the LED head and the main processor, there may be a case where a sufficient communication amount cannot be secured because the clock of the connection interface is low, direct memory transfer is not possible, the processing capacity of the main processor is low, etc. .

  For example, if the main scanning width of the LED array is about 300 mm, the maximum resolution is 1200 dpi, and four-color printing is taken as an example, the light amount correction data in this case is about 60 kbytes at maximum. On the other hand, since the bandwidth of the LED array control circuit and the main processor (generally CPU) is about 2 kbyte / sec, it takes about 30 seconds to complete transmission of all data. That is, since the time until the start of image formation is extended for 30 seconds, the convenience for the user is greatly impaired.

  This problem can be solved by ensuring a sufficiently wide band (light intensity correction data transmission band) between the LED head control circuit and the main processor, but this increases the cost and hinders the cost reduction. Occurs.

On the other hand, it is known that correction is performed by excluding a small number of LED elements whose optical characteristics are different from other LED elements among the plurality of LED elements constituting the LED array (patent) Reference 2).
This is because, among the thousands of LED elements that make up an LED array, there are only a few elements that differ in optical characteristics from the other elements, and when recording is performed, these few elements. This is based on the premise that even if the LED elements are excluded, no adverse effect appears in the image.
However, according to this, since the correction is performed for the majority of LED elements, the problem cannot be solved.

  The present invention has been made in view of the above problems in the conventional image forming apparatus, and its object is to increase the light quantity of the exposure apparatus without expanding the band for transmitting the light quantity correction data to the exposure control circuit. This is to minimize image quality degradation due to unevenness.

The invention according to claim 1 is an image forming apparatus that includes an image forming unit including an exposure device, and transmits the light amount correction data of the exposure device to an exposure control unit to correct the light amount of the exposure device. Priority determining means for determining the transmission priority between the divided light quantity correction data, and the exposure control of the divided light quantity correction data in the order according to the determined priority. An image forming apparatus including: a transmission and print control unit configured to transmit the light amount correction data, interrupt transmission on the condition that the image formation start time is detected, and perform transmission control to start image formation. is there.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus includes a plurality of image forming units, and the priority determining unit classifies the light amount correction data according to a print color of the image data, and the classification The image forming apparatus determines the transmission priority of the light amount correction data based on the printed color of the image data.
According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus includes a plurality of image forming units, and the priority determining unit exposes the light amount correction data to the image forming units of the exposure apparatus. In the image forming apparatus, the transmission priority of light amount correction data is determined on the basis of the divided exposure start order.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus includes a plurality of image forming units, and the priority determining unit determines the number of pixels for each color of the image data for printing the light amount correction data. An image forming apparatus that classifies and determines a transmission priority of light amount correction data based on the number of pixels for each of the classified colors.
According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the priority determining unit divides the light amount correction data by an exposure position on the main scanning of the exposure unit, and the divided exposure unit. The image forming apparatus determines the transmission priority of light amount correction data based on an exposure position on main scanning.
According to a sixth aspect of the present invention, in the image forming apparatus according to the first aspect, the priority determination unit classifies the light amount correction data based on the presence / absence of the light emission scheduled element, and the light amount based on the presence / absence classification of the light emission scheduled element. An image forming apparatus that determines a transmission priority of correction data.
According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the priority determining unit includes a plurality of image forming units, and classifies the light amount correction data according to the attractiveness of the image forming color. The image forming apparatus determines the transmission priority of the light amount correction data based on the attractiveness of the divided image forming colors.
According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect, the priority determining unit divides the light amount correction data according to an array pattern, and the transmission priority of the light amount correction data based on the divided array pattern. An image forming apparatus that determines
A ninth aspect of the present invention is the image forming apparatus according to any one of the first to eighth aspects, wherein the exposure device is an LED head including an LED array.
A tenth aspect of the present invention is an image forming method in an image forming apparatus that includes an image forming unit including an exposure apparatus and transmits light amount correction data of the exposure apparatus to an exposure control unit to correct the light amount of the exposure apparatus. The light quantity correction data is divided into predetermined divisions, a priority determination step for determining a transmission priority between the divided light quantity correction data, and the divided light quantity correction data in an order according to the determined priority. A transmission and print control step for performing transmission control for interrupting transmission of the light amount correction data on the condition that the image formation start time has been detected and starting image formation. An image forming method.

  According to the present invention, it is possible to minimize deterioration in image quality due to unevenness in the light amount of the exposure apparatus without expanding the band for transmitting the light amount correction data to the exposure control circuit.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure explaining the whole structure of the electrophotographic apparatus which concerns on other embodiment of this invention. 2 is a functional block diagram of the image forming apparatus. FIG. It is a flowchart which shows the procedure of the process which the control part of 1st, 1, 2, 4, 6 and 7 embodiment performs. It is a flowchart which shows the procedure of the process which a control part performs in 3rd, 5th embodiment. It is a figure for demonstrating prioritization by the position on the main scanning of light quantity correction data. It is a figure for demonstrating prioritization by the light emission plan element. It is a figure for demonstrating prioritization by the arrangement pattern of light quantity correction data.

The present invention is necessary without increasing the light amount correction data transmission time of the exposure apparatus on the assumption that the bandwidth between the control circuit of the exposure apparatus (for example, LED array) and the main processor remains the same as before. Correction of the light quantity of a simple exposure apparatus.
For this reason, priorities are assigned to the light quantity correction data that have a great influence on the image quality, and the order of transmission is performed according to the priorities. As a result, even when all data cannot be transmitted within a limited time, the image quality improvement effect by the light amount correction is maximized under the limited conditions.

Hereinafter, an embodiment of an image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an overall configuration of an image forming apparatus according to the present embodiment.
In the figure, reference numeral 5 denotes a conveyance belt that conveys a sheet (recording sheet) 4 that is separated and fed from the sheet feed tray 1 by the sheet feed roller 2 and the separation roller 3. In the image forming apparatus, a plurality of image forming units (electrophotographic process units) 6BK, 6M, 6C, and 6Y are arranged along the transport belt 5 in order from the upstream side to the downstream side in the transport direction. The so-called tandem type.

Here, the image forming unit 6BK forms a black image, the image forming unit 6M forms a magenta image, the image forming unit 6C forms a cyan image, and the image forming unit 6Y forms a yellow image. These image forming units 6BK, 6M, 6C, and 6Y have the same internal configuration although the colors of the toner images to be formed are different as described above.
Therefore, in the following description, the internal structure of the image forming unit 6BK will be specifically described by taking the image forming unit 6BK as an example. The constituent elements of the other image forming units 6M, 6C, and 6Y are denoted by symbols that are distinguished by M, C, and Y instead of BK attached to the respective constituent elements of the image forming unit 6BK.

The conveyor belt 5 is an endless belt wound around a driving roller 7 and a driven roller 8 that are rotationally driven. The drive roller 7 is rotationally driven by a drive motor (not shown). The drive motor, the drive roller 7 and the driven roller 8 constitute drive means for the transport belt 5 which is endless moving means.
At the time of image formation, the paper 4 stored in the paper feed tray 1 is sent out in order from the top, and is attracted and transported by the transport belt 5 by electrostatic attraction, and transported to the first image forming unit 6BK to be black toner. The image is transferred.

  The image forming unit 6BK includes a photosensitive drum 9BK, a charger 10BK arranged around the photosensitive drum 9BK, an LEDA (LED array) head, a developing unit 12BK, a photosensitive cleaner (not shown), a static eliminator 13BK, and the like. It is configured. The LEDA head is configured to expose each of the image forming units 6BK, 6M, 6C, and 6Y.

  In the image formation, the outer peripheral surface of the photosensitive drum 9BK is uniformly charged by the charger 10BK in the dark, and then exposed to irradiation light corresponding to the black image from the LEDA head, thereby forming an electrostatic latent image. Is done. The developing device 12BK visualizes the formed electrostatic latent image with black toner, and forms a black toner image on the photosensitive drum 9BK. The formed toner image is transferred onto the sheet 4 by the transfer unit 15BK at a position (transfer position) where the photosensitive drum 9BK and the sheet 4 on the conveying belt 5 are in contact with each other. By this transfer, an image of black toner is formed on the paper 4. After the toner image transfer has been completed, unnecessary toner remaining on the outer peripheral surface of the photosensitive drum 9BK is wiped off by the photosensitive cleaner, and then the charge is removed by the charge eliminator 13BK, and waits for the next image formation.

  On the other hand, the sheet 4 on which the black toner image is transferred by the image forming unit 6BK is conveyed to the next image forming unit 6M by the conveying belt 5. In the image forming unit 6M, a magenta toner image is formed on the photosensitive drum 9M by a process similar to the image forming process in the image forming unit 6BK, and the toner image is superimposed on the black image formed on the paper 4. And is transcribed. The paper 4 is further transported to the next image forming units 6C and 6Y, and a cyan toner image formed on the photoconductive drum 9C and a yellow toner image formed on the photoconductive drum 9Y by the same process. Are superimposed on the paper 4 and transferred.

  A full color image is formed on the paper 4 through the above process. The sheet 4 on which the full-color superimposed image is formed is peeled off from the conveying belt 5 and the image is fixed by the fixing device 16 and discharged to the outside of the image forming apparatus.

FIG. 2 is a diagram illustrating the overall configuration of another electrophotographic apparatus equipped with an LEDA head.
In FIG. 2, an intermediate transfer belt 5a is disposed here instead of the conveying belt of FIG. 1, and the other configuration is basically the same as that of FIG. The intermediate transfer belt 5 a is an endless belt that is wound around the driving roller 7 and the driven roller 8 and is driven to rotate. The toner images of the respective colors are transferred onto the intermediate transfer belt 5a by the functions of the transfer units 15BK, 15M, 15C, and 15Y at the positions where the photosensitive drums 9BK, 9M, 9C, and 9Y are in contact with the intermediate transfer belt 5a (primary transfer positions). Is transcribed. By this transfer, a full-color image in which images of toners of respective colors are superimposed on the intermediate transfer belt 5a is formed.

  At the time of image formation, the paper 4 stored in the paper feed tray 1 is sent out in order from the top and conveyed onto the intermediate transfer belt 5a. The full color toner image is transferred onto the sheet 4 at a position where the intermediate transfer belt 5a and the sheet 4 are in contact (secondary transfer position 21). A secondary transfer roller 22 is disposed at the secondary transfer position 21, and the transfer efficiency is increased by pressing the paper 4 against the intermediate transfer belt 5a. The secondary transfer roller 22 is in close contact with the intermediate transfer belt 5a and has no contact / separation mechanism.

FIG. 3 is a functional block diagram of the image forming apparatus.
The image forming apparatus includes a computer interface unit 24, a print job management unit 26, an image forming process unit 27, a fixing unit 28, an operation unit 29, a storage unit 30, and a reading unit, which are connected to the control unit 32 as shown in the figure. 31, a writing unit 33, a line memory 34, and a nonvolatile storage unit 35.
Here, the computer interface unit 24 constitutes a communication unit that communicates with a host computer that issues a print request to the image forming apparatus.
The print job management unit 26 manages the printing order for print jobs requested by the image forming apparatus.
The image forming process unit 27 creates a toner image from an image stored in the storage unit 30 by an electrophotographic method, and transfers the toner image onto a sheet. If misalignment is detected during printing, correction is also performed.

The fixing unit 28 applies heat and pressure to the paper on which the toner image is transferred by the image forming process unit 27 to fix the toner image thereon.
The operation unit 29 is a keyboard, a touch switch, or the like that displays the state of the image forming apparatus and receives an input to the image forming apparatus.
The storage unit 30 is a storage unit such as an HDD (Hard Disk Drive) for storing image data.
The reading unit 31 is, for example, a scanner that converts print information on paper into an electrical signal.
The control unit 32 includes a CPU (Central Processing Unit) and the like, and is a computer for controlling a series of operations of the above blocks. As a function realization means realized by a program, the light amount correction data is previously stored as will be described later. In the determined section, priority determining means 321 for determining a transmission priority between the divided light quantity correction data, and transmission and print control means 322 for controlling transmission and printing of the divided light quantity correction data are provided.
The writing unit 33 converts the image data into a signal for emitting a laser, and turns on the laser.
The line memory 34 stores the image data in a temporary buffer and adjusts the skew amount by image processing.
The nonvolatile storage unit 35 operates a program executed by the control unit 32 and stores light amount correction data suitable for each condition.

Here, the communication band between the control unit 32 and the writing unit 33 is the same as the conventional one, and it is assumed that a certain amount of time (several tens of seconds to several minutes) is required to transmit the light amount correction data.
The control unit 32 can perform multitask processing. For example, an OS (Operating System) is installed and a multi-core configuration is adopted.

Next, priority transmission processing of light amount correction data by the control unit 32 of the image forming apparatus configured as described above will be described.
First Embodiment: Prioritization by Print Color Information FIG. 4 shows a procedure of processing executed by the control unit 32 of the image forming apparatus according to first, second, fourth, sixth, and seventh embodiments described below. FIG.
The first embodiment will be described with reference to FIG.
The priority transmission process of the light amount correction data is started when a program for executing the priority transmission process in the present embodiment is started due to a factor such as the image forming apparatus described above receiving a print request from the host computer.
First, print parameters are read (when there are a plurality of print requests, the parameters of the job to be printed first. The same applies hereinafter) (S101).
In this embodiment, print color information is read as a print parameter.
Here, the print color information is a color of a monochrome image to be imaged here. For example, in the image forming apparatus shown in FIGS. 1 and 2, only black color is used for monochrome printing, and four colors are black, cyan, magenta, and yellow for full color printing. Of course, a combination of two colors and three colors may be used.

  Next, the priority determination means 321 classifies the light amount correction data based on the read print color information, and determines the transmission priority of the light amount correction data based on the classification (S102). For example, the print color information is black only. In this case, the priority of the light amount correction data of LEDA_BK is set higher than the light amount correction data for LEDA of other print colors. This is because the printing color is only BK, and there is a delay in the light emission start time of the LEDA of other colors.

  Next, the transmission and print control unit 322 determines whether the print start time has been reached, for example, using an internal clock (S103). If the print start time has not been reached (S103, NO), the print start time is reached. The transmission of the light amount correction data is continued until S104. Although there are various ways to set the printing start time, in general, all of the image data to be printed can be stored in the nonvolatile storage unit 35 and the heating in the fixing unit 28 can be fixed. In many cases, this time point is also used in this embodiment. However, the print start time can be arbitrarily set as long as printing can actually start.

  In step S <b> 104, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device from among the light amount correction data stored in the nonvolatile storage unit 35, and transmits it to the writing unit 33. Here, the light amount correction data of LEDA_BK is preferentially transmitted based on the priority determined in step S102.

If the transmission and printing control unit 322 determines that the print start time has been reached in step S103 (S103, YES), the transmission and printing control unit 322 aborts the transmission of the light amount correction data in step S104 and starts printing (S105).
For the LED (light emitting element) that has not received the light amount correction data when the transmission of the light amount correction data is terminated, the LED is caused to emit light with the correction data of the default value or the previous value.
According to the present embodiment, the light amount correction data corresponding to the print color is preferentially transmitted, so that the transmission of the light amount correction data for the print color may be in time (that is, completed) until the print start time is reached. There can be an improvement in image quality.

Second Embodiment: Prioritization by Time Series Exposure Start Order of Print Colors A second embodiment will be described with reference to FIG.
In this case as well, due to factors such as receiving a print request from the host computer, the program for carrying out the present invention is started and the priority transmission process of the light quantity correction data is started.
First, print parameters are read (S101). In this embodiment, print color information is read in the same way as in the first embodiment. Also in this case, in the image forming apparatus shown in FIGS. 1 and 2, only black color is used for monochrome printing, and four colors are black, cyan, magenta, and yellow for full color printing. A combination of two colors and three colors, or a single color of cyan, magenta, and yellow may be used.

  Next, the priority determination means 321 determines the transmission priority of the light amount correction data (S102). For example, it is assumed that the print color information is magenta, cyan, and yellow. In this case, in the image forming apparatus shown in FIGS. 1 and 2, since the LEDA (array) starts exposure in the order of the printing colors LEDA_M, LEDA_C, and LEDA_Y in time series, the light amount correction data is set in the exposure order of the LEDA. The transmission priority of the light quantity correction data is determined based on the classification. That is, the light amount correction data for LEDA_M, the light amount correction data for LEDA_C, and the light amount correction data for LEDA_Y are in this order. This is because there is no time delay in the order of LEDA_M, LEDA_C, and LEDA_Y.

Next, it is determined whether or not the print start time has been reached by the transmission and print control means 322, for example, an internal clock (S103). When it is determined that the print start time has not been reached (S103, NO), the transmission of the light amount correction data is continued according to the priority determined in step S102 until the print start time is reached (S104).
In step S <b> 104, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device from among the light amount correction data stored in the nonvolatile storage unit 35 and causes the writing unit 33 to transmit the selected light amount correction data. Here, the light amount correction data of LEDA_M, LEDA_C, and LEDA_Y is transmitted in chronological order of exposure start according to the priority determined in step S102.

When it is determined in step S103 that the transmission and print control unit 322 has reached the print start time (S103, YES), the transmission of the light amount correction data in step S104 is terminated, and the transmission and print control unit 322 starts printing. (S105). For the LED (light emitting element) that has not received the light amount correction data when the transmission of the light amount correction data is terminated, the LED is caused to emit light with the correction data of the default value or the previous value.
According to the present embodiment, the light amount correction data is sequentially transmitted according to the print color exposure start (light emission) time series, whereby the light amount correction data may be transmitted before the start of exposure of each color, thereby improving image quality. Can be expected.

Third Embodiment: Prioritization by Number of Pixels FIG. 5 is a flowchart showing a procedure of processes executed by the control unit 32 in the third and fifth embodiments.
A third embodiment will be described with reference to FIG.

Also in this case, due to factors such as receiving a print request from the host computer, the program for executing the processing of the present embodiment is started and the priority transmission processing of the light amount correction data is started.
Next, the print parameters are read (S201), and the image data stored in the nonvolatile storage unit 35 is read (S202). After reading the image data, the number of print pixels for each image data is counted. No light emission is counted as 0, and all others are counted as 1. When one pixel is multivalued, the density information may be summed for each pixel.

  Next, the priority determining means 321 determines the transmission priority of the light amount correction data. That is, here, the light amount correction data is divided by the number of print pixels counted in step S202, and the priority is determined in descending order of the number of print pixels based on the division (S203). Next, the light quantity correction data is transmitted according to the determined priority. That is, if the number of Y-color print pixels> the number of M-color print pixels> the number of C-color print pixels> the number of K-color print pixels, the light amount correction data transmission priority is the light amount correction data for LEDA_Y and the light amount correction for LEDA_M. Data, LEDA_C light amount correction data, and LEDA_BK light amount correction data. This is because a color having a smaller number of print pixels has a lower influence on the image quality, and therefore the light amount of a print color having a larger number of print pixels is corrected with higher priority.

  Next, the transmission and print control unit 322 determines whether the print start time has been reached, for example, using an internal clock (S204). If it is determined that the print start time has not been reached (S204, NO), the print start is started. The transmission of the light amount correction data is continued until the time is reached (S205).

  In step S <b> 205, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device from among the light amount correction data stored in the nonvolatile storage unit 35 and causes the writing unit 33 to transmit the selected light amount correction data. That is, according to the priority determined in step S203, the LEDA_Y light amount correction data, LEDA_M light amount correction data, LEDA_C light amount correction data, and LEDA_BK light amount correction data are transmitted in this order.

If the transmission and print control unit 322 determines that the print start time has been reached (S204, YES), the transmission of the light amount correction data in step S205 is terminated and printing is started (S206).
For light emitting elements that have not received the light amount correction data when the transmission of the light amount correction data is terminated, the light emitting element is caused to emit light with the correction data of the default value or the previous value.

  According to the present embodiment, the light amount correction data corresponding to the number of print pixels is transmitted, so that the image quality is greatly influenced. Therefore, the maximum effect can be obtained with limited light quantity correction data.

Fourth Embodiment: Prioritization of Light Amount Correction Data by Position on Main Scan A fourth embodiment will be described with reference to FIG.
Also in this case, due to factors such as receiving a print request from the host computer, the program for executing the processing of the present embodiment is started and the priority transmission processing of the light amount correction data is started.
Next, print parameters are read (S101). In this embodiment, print color information is read. For simplification of the description below, it is assumed that the printing color is only BK color.
Next, the priority determination means 321 classifies the light quantity correction data along a position corresponding to the main scanning direction, and determines the transmission priority of the light quantity correction data based on this classification (S102). FIG. 6 is a diagram in which light amount correction data is divided into areas 1 to 6 along a position corresponding to the main scanning direction of LEDA_BK in all areas 60 of light amount correction data. In general, the printed image is most conspicuous at the center of the image, and image quality is required. Therefore, the light amount correction data corresponding to the center of the LEDA_BK in the main scanning direction is transmitted. In the example shown in FIG. 6, the priorities are in the order of areas 3, 4, 2, 5, 1, 6 in the main scanning direction. In one area, the light amount correction data may be divided for each LED (light emitting element) or for each of a plurality of LEDs.

In step S101, if the print color information is full color, the priority determination in step S102 can be considered in various ways, but the following may be combined with the method of the second embodiment.
That is, the transmission and printing control unit 322 performs BK areas 1, 2,... 6 M area 1, 2,... 6 C area 1, 2,. 2 ... 6, BK area 3, 4, 2, 5, 1, 6 M area 3, 4, 2, 5, 1, 6 C area 3, 4, 2, 5, 1, 6, Y The light quantity correction data is transmitted in the priority order of areas 3, 4, 2, 5, 1, and 6.

  Thus, it is also possible to determine the priority in combination with other embodiments and transmit the light amount correction data. In addition, it is not limited to the combination of said 1st Embodiment and 2nd Embodiment, The combination with other embodiment is also possible.

Next, the transmission and print control unit 322 determines whether the print start time has been reached, for example, using an internal clock (S103). If it is determined that the print start time has not been reached, the transmission and print control unit 322 continues until the print start time is reached. Then, the transmission of the light quantity correction data is continued (S104).
In step S <b> 104, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device from among the light amount correction data stored in the nonvolatile storage unit 35 and causes the writing unit 33 to transmit the selected light amount correction data. The light amount correction data is transmitted in the order of areas 3, 4, 2, 5, 1, 6 in accordance with the priority determined in step S102.

When it is determined in step S103 that the transmission and print control unit 322 has reached the print start time (S103, YES), the transmission of the light amount correction data in step S104 is terminated, and the transmission and print control unit 322 starts printing. (S105). An LED (light emitting element) that has not received the light amount correction data when transmission of the light amount correction data is terminated emits light with the correction data of the default value or the previous value.
According to the present embodiment, even when all the light amount correction data cannot be transmitted by transmitting the light amount correction data corresponding to the position of the LED on the main scan to be corrected by the light amount correction data, the influence is minimized. Can be.

Fifth Embodiment: Prioritization by Light-Emitted LEDs The fifth embodiment will be described with reference to FIG.
Also in this case, due to factors such as receiving a print request from the host computer, the program for executing the processing of the present embodiment is started and the priority transmission processing of the light amount correction data is started.
Next, print parameters are read (S201). Next, the image data stored in the nonvolatile storage unit 35 is read (S202).
Next, the priority determination means 321 determines the transmission priority of the light amount correction data (S203). Here, a method for determining the transmission priority of the light amount correction data in step S203 will be described with reference to FIG.

Assume that the image data in the nonvolatile storage unit 35 is the image data 40 shown in FIG. In this case, the LED (s) scheduled to emit light from LEDA takes a logical OR for each pixel, with the light emitting pixel being 1 and the non-light emitting pixel being 0 in the sub-scanning direction with respect to the image data (in FIG. Part, that is, the part corresponding to the printed part emits light). Then, the light emission scheduled pixel (group) becomes the light emission scheduled LED 41 on the LED head of FIG.
Therefore, the priority determination means 321 classifies the light amount correction data corresponding to the pixel (group) to be emitted, and determines the transmission priority of the light amount correction data based on this division.
Here, assuming that the area classification of the image correction data is indicated by reference numeral 42, the light emission scheduled pixels (groups) are included in areas 2 and 3. Make it high. This is because there is no need to correct the amount of light if it is a non-light emitting element, and priority is given to correcting the light amount of the light emitting element, which contributes to improvement in image quality.

Next, the transmission and print control unit 322 determines whether the print start time has been reached, for example, using an internal clock (S204). If it is determined that the print start time has not been reached (S204, NO), the print start is started. The transmission of the light amount correction data is continued until the time is reached (S205).
In step S205, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device in accordance with the priority determined in step S202 from among the light amount correction data stored in the nonvolatile storage unit 35. Then, the data is transmitted to the writing unit 33. Here, the correction data of areas 2 and 3 is preferentially transmitted among the light amount correction data of LEDA_BK.

  Next, when the transmission and print control means 322 determines that the print start time has come (S204, YES), the transmission of the light amount correction data in step S205 is terminated and printing is started (S206). For the LEDs for which reception of the light amount correction data has not been completed when transmission of the light amount correction data is terminated, the LED emits light with the correction data of the default value or the previous value.

  According to the present embodiment, the light amount correction data corresponding to the number of print pixels is transmitted, so that the image quality is greatly influenced. Therefore, the maximum effect can be obtained only by transmitting limited light amount correction data.

Sixth embodiment: Prioritization by attractiveness A sixth embodiment will be described with reference to FIG.
Also in this case, due to factors such as receiving a print request from the host computer, the program for executing the processing of the present embodiment is started and the priority transmission processing of the light amount correction data is started.
Next, print parameters are read (S101). In the present embodiment, print color information is read (in the following, for the sake of simplification of explanation, a case of full color (black, magenta, cyan, yellow) will be described as an example).

Next, the priority determination means 321 determines the transmission priority of the light amount correction data (S102). That is, the priority determination unit 321 classifies the light amount correction data based on the attractiveness of the print color, and determines the order of the LEDs A for performing the light amount correction based on the classification. Although the attractiveness may vary slightly depending on the toner color, the priority is generally determined in the order of black, magenta, cyan and yellow. Thereby, it correct | amends from the light quantity of LEDA of the color which is conspicuous.
Next, the transmission and print control unit 322 determines whether the print start time has come, for example, by an internal clock (S103). If it is determined that the print start time has not come (S103, NO), the print start time is set. The transmission of the light quantity correction data is continued until it reaches (S104).

In step S <b> 104, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device from among the light amount correction data stored in the nonvolatile storage unit 35 and causes the writing unit 33 to transmit the selected light amount correction data. Here, the light amount correction data is transmitted in the order of black, magenta, cyan, and yellow based on the determination result of the transmission priority of the light amount correction data in step S102.
When it is determined in step S103 that the print start time has been reached (S103, YES), the transmission of the light amount correction data in step S104 is terminated and printing is started (S105).
For light emitting elements that have not received the light amount correction data when the transmission of the light amount correction data is terminated, the light emitting element emits light with the correction data of the default value or the previous value.

  In this way, by correcting the amount of light from the attractive print color, even when all the light amount correction data cannot be transmitted, image quality deterioration such as color unevenness is less noticeable and image quality improvement is expected. it can.

Seventh Embodiment: Correction based on arrangement pattern A seventh embodiment will be described with reference to FIG.
Also in this case, due to factors such as receiving a print request from the host computer, the program for executing the processing of the present embodiment is started and the priority transmission processing of the light amount correction data is started.
Next, print parameters are read (S101). In the present embodiment, print color information is read (in the following description, for the sake of simplicity, the case of only black color will be described as an example).
Next, the priority determination means 321 determines the transmission priority of the light amount correction data (S102). Here, a method of determining the transmission priority of the light amount correction data will be described with reference to FIG. When all the areas 52 of the light amount correction data are allocated in a grid pattern with respect to the LED positions of the LEDA, the priority determining unit 321 divides the light amount correction data for each area, for example, and based on this division. Break down. In the example of FIG. 8, priorities are given by an array that determines priority areas for each area, that is, for example, correction is performed by skipping one pixel (since skipping one pixel makes it difficult to stand out as a whole). Of course, there may be two areas or various arrangements such as a random arrangement.
In the present embodiment, the area is preferably as small as possible.

Next, the transmission and print control means 322 determines whether the print start time has been reached, for example, with an internal clock (S103). If it is determined that the print start time has been reached (S103, YES), the print start time is determined. The transmission of the light amount correction data is continued until it reaches (S104).
In step S <b> 104, the transmission and print control unit 322 selects light amount correction data suitable for the environment of the device from among the light amount correction data stored in the nonvolatile storage unit 35 and causes the writing unit 33 to transmit the selected light amount correction data.
If the transmission and print control means 322 determines in step S103 that the print start time has come (S103, YES), the transmission of the light amount correction data in step S104 is terminated and printing is started (S105).
For the LEDs for which reception of the light amount correction data has not been completed when transmission of the light amount correction data is terminated, the LED emits light with the correction data of the default value or the previous value.

  According to the present embodiment, by performing light amount correction along a specific arrangement pattern of light amount correction data, even when all of the light amount correction data cannot be transmitted, the image quality deterioration is not conspicuous as a whole, and the image quality is improved. I can expect.

As mentioned above, although embodiment of this invention was described, it is as follows when putting it together.
The standard for giving the transmission priority to the light quantity correction data is as follows.
(I) Print color (For example, only black light intensity correction is performed for monochrome printing)
(Ii) Exposure start order in time series (for example, when exposure is performed in the order of K->M->C-> Y, transmission is performed from K. Because the light quantity can be corrected to the last minute in the time series)
(Iii) Number of pixels for each color to be printed (for example, if the number of pixels is small, the proportion of the image is low, so even if the image quality is somewhat low, it is not noticeable)
(Iv) The position of the light emitting element to be corrected by the light quantity correction data on the main scan (for example, the center is more conspicuous and the edge is relatively inconspicuous)
(V) LED to emit light (for example, it is not necessary to perform light amount correction for an LED that does not emit light)
(Vi) The attractiveness of the formed color (for example, the Y color is inconspicuous, so the priority is lowered)
(Vii) Arrangement pattern (For example, correction is performed by skipping pixels. If one pixel is skipped, it is difficult to stand out as a whole)

According to this embodiment, in order to give priority to the light amount correction data and transmit from the highest priority,
(I) Maximum image quality improvement can be obtained from a limited amount of light correction data. As a result, the light amount correction data transmission band does not increase, which contributes to a reduction in the cost of the image forming apparatus.
(Ii) Since the light amount correction data is transmitted only within the time until the start of image formation, the time until the start of image formation is not extended, and thus the convenience for the user is not impaired.

  In the above description, the image forming unit has been described as a so-called tandem type in which a plurality of image forming units are arranged at predetermined intervals. However, Embodiments 4, 5, and 7 are not necessarily limited thereto. The image forming unit may be single.

  DESCRIPTION OF SYMBOLS 1 ... Paper feed tray, 2 ... Paper feed roller, 3 ... Separation roller, 4 ... Paper, 5 ... Conveyance belt, 5a ... Intermediate transfer belt, 6BK, 6M, 6C, 6Y: image forming unit (electrophotographic process unit), 7: driving roller, 8: driven roller, 9BK, 9M, 9C, 9Y ... photosensitive drum, 10BK, 10M, 10C, 10Y ..Charging unit, 12BK, 12M, 12C, 12Y ... developing unit, 13BK, 13M, 13C, 13Y ... charge eliminating unit, 15BK, 15M, 15C, 15Y ... transfer unit, 16 ... fixing unit , 22 ... secondary transfer roller, 24 ... computer interface unit, 26 ... print job management unit, 27 ... image forming process unit, 28 ... fixing unit, 29 ... operation unit, 30 ... storage unit, 31 ... reading unit, 2 ... controller, 33 ... writing unit, 34 ... line memory, 35 ... nonvolatile memory unit.

JP-A-9-309223 JP-A-62-200966

Claims (10)

An image forming apparatus that includes an image forming unit including an exposure device, transmits light amount correction data of the exposure device to an exposure control unit, and corrects the light amount of the exposure device,
The light quantity correction data is divided into predetermined divisions, priority determination means for determining the transmission priority between the divided light quantity correction data, and the divided light quantity correction data in the order according to the determined priority. An image forming unit including: a transmission control unit configured to transmit to the exposure control unit and to interrupt the transmission of the light amount correction data on the condition that the image formation start time is detected, and to perform transmission control to start image formation. apparatus. The image forming apparatus according to claim 1,
An image having a plurality of image forming units, wherein the priority determination unit divides the light amount correction data by a print color of the image data, and determines a transmission priority of the light amount correction data based on the print color of the divided image data. Forming equipment. The image forming apparatus according to claim 1,
A plurality of image forming units, and the priority determination unit divides the light amount correction data according to an exposure start order in each of the image forming units of the exposure apparatus, and sets the light amount correction data based on the divided exposure start order. An image forming apparatus that determines a transmission priority. The image forming apparatus according to claim 1,
A plurality of image forming units, wherein the priority determination unit divides the light amount correction data according to the number of pixels for each color of the image data to be printed, and transmits the light amount correction data based on the divided number of pixels for each color. An image forming apparatus that determines priority. The image forming apparatus according to claim 1,
The priority determination unit divides the light amount correction data by the exposure position on the main scanning of the exposure unit, and determines the transmission priority of the light amount correction data based on the divided exposure position on the main scanning of the exposure unit. Forming equipment. The image forming apparatus according to claim 1,
The priority determination unit classifies light amount correction data according to presence / absence of light emission scheduled elements, and determines a transmission priority of light amount correction data based on the presence / absence of light emission scheduled elements. The image forming apparatus according to claim 1,
The priority determination means includes a plurality of image forming units, classifies the light amount correction data according to the attractiveness of the image forming color, and determines the transmission priority of the light amount correction data based on the attractiveness of the classified image forming color. Image forming apparatus. The image forming apparatus according to claim 1,
The priority determination unit is an image forming apparatus that divides by an array pattern of light amount correction data and determines a transmission priority of the light amount correction data based on the divided array pattern. The image forming apparatus according to claim 1,
The exposure apparatus is an image forming apparatus which is an LED head including an LED array.   An image forming method in an image forming apparatus, comprising: an image forming unit including an exposure apparatus; and transmitting the light amount correction data of the exposure apparatus to an exposure control unit to correct the light amount of the exposure apparatus. A priority determination step for determining a transmission priority between the divided light quantity correction data, and transmitting the divided light quantity correction data to the exposure control means in an order according to the determined priority. And a transmission and printing control step for performing transmission control for interrupting transmission of the light amount correction data on the condition that the image formation start time is detected and starting image formation.

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