JP2013109240A - Image forming apparatus, image forming system, light source control method, program and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus of an electrophotographic system capable of saving the power by reducing the light emitting amount smaller than conventional when controlling lighting of light source using image data which is drawn based on printing data without reducing the image quality.SOLUTION: A PDL interpretation means 110 interprets a piece of printing data received from a host to obtain a piece of intermediate data representing drawing conditions such as a drawing object, and transfers the same to object identification means 111 and drawing processing means 112 located at the downstream. When turning ON output means 118 (LD light source) using the data processed by the drawing processing means 112, the light source drive control means 117 controls the light emitting amount by setting a small light emitting amount control value in a divided image area where drawing object exists for which the light emitting amount can be reduced in a range causing no reduction of the image quality based on a "divided image area-drawing object table" created by the object identification means 111 and the light emitting amount control value corresponding to the type of the drawing object which is separately prepared.

Description

  The present invention relates to a printer and a multifunction peripheral that scan and expose a photosensitive member with light from a light source whose lighting is controlled by output image data generated based on print data, and form an image on recording paper by an electrophotographic method The present invention relates to an image forming apparatus, an image forming apparatus that performs control to reduce power consumed by the light source, an image forming system, a light source control method, a program for executing the control, and a recording medium on which the program is recorded.

  Conventionally, as a printer engine in an image forming apparatus such as a printer or a multifunction peripheral that forms an image on recording paper based on print data transmitted from a host device such as a PC (Personal computer) equipped with a printer driver, So-called laser printers are widely used. This laser printer performs scanning exposure with a beam emitted from a laser whose lighting is controlled by output image data drawn based on print data, and forms an image by electrophotography.

In recent years, there has been a growing awareness of the environment, and there has been an increasing demand for power consumption based on a TEC (Typical Electricity Consumption) value while minimizing the power consumed by the image forming apparatus.
In an electrophotographic image forming apparatus, high temperature heating is required for the process of fixing a toner image on a recording sheet, and power consumption used for this process occupies a considerable part, so the drive of the heating unit in the fixing apparatus is controlled. Many proposals have been made to save power.
Regarding power saving control in the heating section of the fixing process, in addition to power saving control when the printer engine is at rest, such as during standby, control means that works during operation of the printer engine has recently been proposed. For example, patent document 1 (Unexamined-Japanese-Patent No. 2011-186131) can be mentioned.

In the image forming apparatus described in Patent Document 1, it is noted that the minimum fixing temperature required for normal fixing differs depending on the drawing conditions specified in the print data to be processed. In the case where it is not necessary, power saving control is performed to lower the fixing temperature of the control target.
In contrast to the power saving control in the toner image fixing process described above, in the scanning exposure process for forming a toner image, in order to save power, the exposure amount, that is, the light emission amount when a light source such as a laser is turned on, There was no idea of controlling according to the drawing conditions specified in the print data.

However, from experience so far, depending on the drawing conditions specified in the print data, even if the maximum exposure amount is reduced to the predetermined limit amount, the formed image does not deteriorate, for example, characters and line drawings It has been found that the drawing instruction does not cause deterioration in image quality even when the exposure amount is smaller than that for other drawing instructions.
However, in the conventional image forming apparatus, paying attention to the relationship between the above drawing conditions and the limit exposure amount that does not cause a decrease in the output image quality, it is possible to take measures to reduce the power consumed in the light emission of the light source. It has not been proposed, and a power saving operation of a light source that does not cause deterioration in image quality has not been realized.

  An object of the present invention is to realize a power-saving lighting operation that does not cause deterioration in image quality when light source lighting control is performed using image data drawn based on print data.

  The present invention is an image forming apparatus that controls lighting of a light source based on print data, and forms an image by scanning and exposing a photoconductor with light from the light source, the drawing conditions set in the print data, Light emission amount control value storage means for storing the light emission amount control value of the light source determined for each drawing condition in association with each other, and a light emission amount control value corresponding based on the drawing condition set for the print data to be processed Is obtained from the light emission quantity control value storage means, and a light emission quantity control means for controlling the light emission quantity of the light source based on the obtained light emission quantity control value.

  According to the present invention, by performing control to reduce the light emission amount of the light source to a predetermined limit exposure amount that does not deteriorate the image quality according to the drawing conditions, it is possible to realize a power-saving lighting operation that could not be achieved by the conventional technology. it can.

1 is a diagram illustrating a configuration of a print system including a printer according to an embodiment of the present invention as a system element. FIG. 2 is a diagram illustrating a hardware configuration of a printer according to an embodiment of the present invention. It is a figure which shows the structure of the data processing system in the printer shown in FIG. 2 with a functional block. It is a conceptual diagram showing each division | segmentation image area | region of the image formation surface divided | segmented as a process unit area | region. 6 is a table showing an example of a “divided image area-drawing object correspondence table” that represents the types of objects set in each divided image area (see FIG. 4) on the image forming surface. FIG. 5 is a diagram illustrating a flow of print output processing in the printer according to the embodiment of the present invention.

Embodiments of the present invention will be described with reference to the accompanying drawings.
Hereinafter, the image forming apparatus of the present invention is scanned and exposed by a laser beam emitted from a laser printer, that is, an LD (laser diode) light source whose lighting is controlled by drawn image data for output, and an image is obtained by electrophotography. An explanation will be given by taking a printer that forms the above as an example.
This printer generates print output pixel signals (hereinafter also referred to as “print output data” or simply “output image data”) for controlling the lighting of the LD light source for exposure by drawing processing based on the print data. When the processing is performed, a control signal for controlling the light emission amount of the LD light source at the time of lighting is generated by a predetermined control value corresponding to the drawing condition set in the print data.

The control of the light emission amount of the LD light source will be described in detail later, but it depends on the drawing conditions on the premise of an empirical rule that the exposure amount that does not cause deterioration in image quality of the formed image varies depending on the drawing conditions of the drawing object or the like. By adjusting the exposure amount, that is, by controlling the light emission amount of the light source that reduces the excess light amount, it is possible to reduce the power consumption without causing the image quality to deteriorate.
In the following description, a laser printer is illustrated as an embodiment of the present invention. However, if the image forming apparatus is an electrophotographic image forming apparatus that satisfies the above-described assumption and can control the light emission amount, a laser is used. An image forming apparatus other than a printer may be used.

[Print system]
Before describing the printer, an outline of the configuration of a print system that uses the printer as a system element will be described.
FIG. 1 is a diagram illustrating a configuration of a print system according to the present embodiment.
The printing system shown in FIG. 1 is configured by connecting the system elements of the printers 20 ₁ , 20 ₂ , and 20 ₃ and a host PC (Personal computer) 40 as a host device to a network 30. The network 30 can be, for example, a TCP / IP network, but may be any network as long as data exchange is possible.
In the print system shown in the figure, a system having the printers 20 ₁ , 20 ₂ , and 20 ₃ as an example is taken as an example, but a device such as a multifunction machine having a printer function may be used.
Note that the printer engine itself that performs the print output operation can be implemented by using an existing device that can control the light emission amount of the LD light source during lighting when controlling the lighting of the LD light source for exposure. Omit the explanation.

The printers 20 ₁ , 20 ₂ , and 20 ₃ receive print data described in PDL (page description language) that is created by a printer driver installed in the host PC 40 and transmitted via the network 30 and print. Using the output image data drawn based on the data, the printer engine is operated to perform print output.
The host PC 40 is one of external devices that make a print request to the printers 20 ₁ , 20 ₂ , and 20 _3. Such an external device is a device that has a function of making a print request using a printer driver. If there is, it is not limited to a device such as a PC.

[Overview of hardware configuration]
FIG. 2 is a diagram illustrating a hardware configuration of the printer according to the embodiment of the present invention.
The printer 20 shown in the figure includes a controller 10 that controls the entire printer, a printer engine as an output device 23 that performs print output using output image data drawn based on print data by the controller 10, a display And an operation panel 24 having an operation unit such as an input key and functioning as a user interface.
The printer engine as the output device 23 scans and exposes the surface of the photosensitive member with a laser beam emitted from an LD light source whose lighting is controlled by output image data, forms an image by an electrophotographic method, and transfers the image onto a transfer sheet. Since existing hardware that performs print output is used, a description thereof is omitted.

The controller 10 includes a control unit 11 having a CPU (Central Processing Unit) 11 for executing instructions of the software program, and a ROM for storing a control program, control data, and the like used by the CPU 11 to operate the controller. (Read Only Memory), a page (frame) memory for temporarily storing rendered output image data generated by the control program, or a RAM used as a work memory for storing data necessary for the operation of the software program (Random Access Memory), setting data such as processing conditions depending on the device, data for managing the state of the device, and the like, a main storage unit 12 including each memory of NVRAM (Non Volatile RAM), an HDD (Hard
Auxiliary storage unit 13 using (Disk Drive) is included as a component. That is, a computer including the elements of the CPU 11, the main storage unit 12, and the auxiliary storage unit 13 is caused to function as the controller 10.

Further, the controller 10 includes an output interface (I / F) 16 for exchanging data with the output device 23, an operation panel I / F 17 for exchanging data with the operation panel 24, a TCP A network I / F 15 for exchanging data with a host PC 40 (see FIG. 1) connected on a network such as an / IP network is included as a constituent element. The I / F with an external device (host PC 40) that transmits print data is a communication I / F that exchanges data with an external device in addition to a network I / F 15 such as a TCP / IP network. Any means may be used.
Further, the above-described elements constituting the controller 10 are connected via an internal bus 19.

The controller 10 performs a drawing process including various conversion processes based on the print data described in PDL received from the host PC 40, generates output image data, and outputs the print output together with other output conditions. These data are transmitted to the device 23, and the output device 23 is caused to perform print output. The RAM of the main storage unit 12 stores print data from the host PC 40, image data in an intermediate data format generated from the print data, and output image data (print output pixel signal) generated by subsequent processing. To do.
The printer 20 reads a control program stored in a storage device such as a ROM or NVRAM in the main storage unit 12 and setting information related to operation conditions of control and processing, and provides a work memory area for the CPU (control unit) 11. By expanding the memory area of the RAM of the storage unit 12 and using the RAM as a work area for image forming processing, means for realizing the functions shown in FIG.

Software configuration
The host PC 40 uses a predetermined printer driver to convert a document created or processed by an application into print data describing drawing conditions including various drawing commands, and transmits the print data to the printer 20 via the network 30. Request printout. The drawing command is usually a command for instructing each drawing object of characters, images, and graphics. The print data is expressed by data described in various PDLs such as PostScript (registered trademark), PCL (registered trademark), and RPDL (registered trademark).

When the controller 10 of the printer 20 performs processing for generating output image data for controlling lighting of an exposure laser light source by drawing processing based on print data from the host PC 40 received via the network I / F 15. In addition, a control signal for controlling the light emission amount of the laser light source at the time of lighting is generated with a predetermined control value corresponding to the drawing condition set in the print data.
For this reason, in addition to the PDL processing function of an existing printer, elements necessary for the light emission amount control function are added to the control unit 11 of the controller 10 as a data processing system configured by software.

FIG. 3 is a functional block diagram showing the configuration of the data processing system installed in the printer 20 shown in FIG. The arrows shown in the figure indicate the flow of data processing. This data processing system is realized by a program as a function realizing unit of a computer constituted by the control unit 11 and the main storage unit 12.
In the data processing system of FIG. 3, the PDL interpretation unit 110 requests a print and draw commands (drawing objects and their attributes) and colors obtained by interpreting print data described in PDL transmitted from the host PC 40. Intermediate data representing drawing conditions, such as drawing setting information having transparency settings and the like, is passed to the object identifying unit 111 and the drawing processing unit 112 in the subsequent stage.

The object identification unit 111 identifies various drawing objects based on the received intermediate data of the drawing conditions, and collects drawing setting information, information on the area where the drawing object exists, and the like for each drawing object type. In addition, the information of the area where the drawing object exists is recorded in the auxiliary storage unit 13 for each type of drawing object obtained as a processing result by the object identification unit 111. The area information corresponding to the predetermined drawing object recorded in the auxiliary storage unit 13 is referred to as information necessary for the light emission amount control of the subsequent light source.
Note that when the controller 10 that controls the entire printer controls the operation of the data processing system in FIG. 3 in response to a print output request, information used for the control is stored and managed in the auxiliary storage unit 13 in this embodiment. To do. One of the information stored and managed in the auxiliary storage unit 13 is area information corresponding to the above-described predetermined drawing object (see and described below regarding “divided image area-drawing object correspondence table”). It includes a light emission amount control value corresponding to a drawing object used for controlling the light source described later. The information used for the control is stored in the HDD of the auxiliary storage unit 13. However, the information stored temporarily until the output process such as “divided image area-drawing object correspondence table” is completed is the main memory. The RAM of the unit 12 may be used.

  The drawing processing unit 112 receives drawing setting information for each type of drawing object, information on a region where the drawing object exists, and the like collected by the object identification unit 111 as drawing target data, and performs rendering processing for each drawing object. Thus, image data for print output is generated. The generated image data is stored in the RAM of the main storage unit 12 or the HDD of the auxiliary storage unit 13.

The light source drive control means 117 generates a drive control signal for the LD light source that is the output means 118. This drive control signal is a control signal for lighting on / off control and light emission amount control. The lighting on / off control signal is a signal generated by the drawing processing unit 112 based on image data for print output obtained by rendering processing of each drawing object. Further, the light emission amount control signal generates a control signal for instructing a light emission amount control value for each region based on the region information corresponding to the drawing object previously recorded in the storage unit through the processing of the object identification unit 111. .
The light emission of the LD light source used for the output means 118 is controlled by the above-described drive control signal of the LD light source, and the photosensitive member surface is scanned and exposed by the laser beam output from the LD light source to generate an electrostatic latent image.

[Light emission control of light source corresponding to drawing conditions]
Next, in the laser printer of this embodiment, the control of the light emission amount of the LD performed to reduce the power consumed by the light emission of the LD that is the light source used for scanning exposure will be described in detail.
When performing scanning exposure on the surface of a photoreceptor with a laser beam emitted from an LD light source whose lighting is controlled by output image data, depending on the drawing object, the difference in the image quality of the printed image appears even if the light emission amount is changed. The relationship between the drawing object and the amount of light emission is known as an empirical rule. For example, an image of a drawing object that draws a character / line drawing and an image of a drawing object that draws a solid image (a pattern image in which the inside is filled with the same value pixels) are determined to obtain the same target potential (output charge amount). Even if the exposure is performed with a large amount, the former appears higher than the target potential, and the latter appears lower than the target potential inside the image. This seems to be due to the edge effect.

However, control operations based on the concept of changing the exposure amount according to the type of drawing object have not been performed, and the light source emission amount that uniformly applies a large exposure amount that can be applied to any drawing object is supported. Thus, a method of securing a target potential (output charge amount) is adopted. For this reason, depending on the drawing object, an unnecessarily large exposure amount is given, and unnecessary power is consumed accordingly. That is, in the above example, in order to secure the target potential in the solid image, the character / line drawing is exposed with an amount more than necessary.
Therefore, in this embodiment, by controlling the light emission amount of the light source that reduces the excess light amount of the pixel area of the drawing object that has given an exposure amount that is more than necessary, the power consumption can be reduced without causing image quality degradation. Enable.

In this light emission amount control method, first, for each of a plurality of types of drawing objects, the smallest exposure amount (light emission amount of the light source) allowed within a range in which the image quality does not deteriorate is obtained by performing an experiment or the like. Information representing the relationship between the type of drawing object and the light emission amount control value of the light source used for the light emission amount control for reducing power consumption based on the result is referred to as a table (hereinafter referred to as “drawing object-light emission amount control value correspondence table”). ) Etc. in advance.
At the time of print output, the light emission amount control value corresponding to the drawing object set in the print data to be processed is acquired from the prepared “drawing object-light emission amount control value correspondence table” and acquired. A method is adopted in which the light emission amount of the light source that is turned on by the print output image data is controlled by the light emission amount control value.

If the light emission amount control by the above method is performed in units of pixels, the amount of data increases and the control becomes complicated. Therefore, in this embodiment, the image surface to be printed is divided into regions of a predetermined size, and each divided image region is divided. A light emission amount control value to be applied to is determined (see the description of FIGS. 4 and 5 below).
When determining the light emission amount control value to be applied to the divided image area, the number of drawing objects set in the divided image area is not limited to one. Therefore, for each drawing object identified as a drawing object in each divided image area from the print data. The corresponding light emission amount control value is acquired from the “drawing object-light emission amount control value correspondence table”, and for example, the maximum value among the acquired light emission amount control values is determined as the light emission amount control value to be applied to each divided image region. The light emission amount control value of the light source that is turned on in each divided image region is set according to the determination result.
Therefore, when scanning exposure is performed with a beam emitted from the LD light source, if the light emission amount control value set between the divided image regions is different, the light emission amount switching control is performed. Note that the light emission amount switching control is performed, for example, by changing the LD driving current during lighting according to the control value.

The procedure for determining the light emission amount control value for each divided image area will be described in detail below.
In the data processing system of FIG. 3, as described above, the object identification unit 111 detects the information of the area where the drawing object exists for each drawing object, and passes this information to the light source drive control unit 117 at the subsequent stage. The light source drive control unit 117 records the received information in the auxiliary storage unit 13 in order to set a light emission amount control value to be applied to the divided image area.
At this time, one method of recording in the auxiliary storage unit 13 is to assign a serial number to each drawing object and set an area (in this embodiment, a divided image area) where each drawing object and an image drawn by the drawing object exist. There is a way to record in. However, according to this method, when the light emission amount control value is set by the light source drive control unit 117, the area where the images of all the drawing objects exist is read again, and the overlapping of images drawn by different drawing objects for each divided image area is overlapped. It is necessary to check the condition.

<Divided image area subject to emission control>
Therefore, the light source drive control means 117 assigns a serial number to each divided image area obtained by dividing the image surface to be printed into areas of a predetermined size (hereinafter referred to as “area number”), and is in that area using the area number as a key. A method of recording the type of drawing object is adopted. A table created by this method is hereinafter referred to as a “divided image region-drawing object correspondence table”.

FIG. 4 is a conceptual diagram showing each divided image area of the image forming surface to be divided as a processing unit area.
As shown in the figure, the entire image forming surface 50 is divided into 15 divided image regions 50d, each of which is assigned a serial number (1) to (15), and each divided image region 50d is a light emission amount control target. As an area, a process for setting a light emission amount control value is performed for each area.
It should be noted that the number of divisions of the divided image area 50d is preferably determined dynamically in accordance with the transfer sheet size, considering an appropriate size based on the capability of the drive control unit of the LD of the printer engine as the output device 23.

<Divided image area-drawing object correspondence table>
When the divided image area 50d illustrated in FIG. 4 is used as a processing unit and the method of recording the type of the drawing object in each divided image area 50d is adopted, it is associated with the area numbers (1) to (15) as keys. Thus, a “divided image area-drawing object correspondence table” indicating whether or not there is a drawing object having an image in the area is created.
FIG. 5 is a table showing an example of a “divided image area-drawing object correspondence table” that indicates the type of object set in each divided image area 50d (see FIG. 4) of the image forming surface 50.
The table shown in the figure has three types of drawing object columns in a format corresponding to the area numbers (1) to (15), and indicates whether or not an image of each drawing object exists. Here, three types of drawing objects, that is, a “character image” by a character object, a “line image” by a graphic object, and a “solid image” by a graphic object are target objects.

In the table creation procedure of FIG. 5, first, the number of divisions of the image forming surface 50 is determined, a divided image area 50d (see FIG. 4) is set, and a table with the area number as a key is generated in the storage means. . In the setting example of the divided image area in FIG. 4, the initial state table shown in FIG. 5A is generated in a format corresponding to the area numbers (1) to (15).
Next, at the time of drawing object identification processing indicated in the drawing command of the print data to be processed, it is confirmed in which divided image area each drawing object exists, and the three types of drawing objects provided in the existing area numbers are checked. Of these, “present” data is written in the column corresponding to the type of the target drawing object.
By repeating this writing process for the number of drawing objects present in the print data, a “divided image region-drawing object correspondence table” required for the print data to be processed shown in FIG. 5B is created.

In addition, by storing the overlapping order of the drawing objects in the divided image region in the “divided image region-drawing object correspondence table” in FIG. 5, based on these information immediately before the light emission amount, This can be implemented by a procedure for rewriting a set value table used for light emission amount control.
As described above, according to the method of referring to the table of FIG. 5, the light source drive control unit 117 uses the “divided image region-drawing object correspondence table” as the information on the divided image region indicated by the region number to be the light emission amount control target. Therefore, the above-described processing for reading out the divided image areas related to all the drawing objects and confirming the overlapping state of the images, which is performed when setting the light emission amount control value, becomes unnecessary.

Further, when creating the “divided image region-drawing object correspondence table”, the drawing object type information has a priority order such as increasing the priority of the drawing object type for which the light emission amount control value must be increased. In addition, it is possible to adopt a method of creating data by overwriting when it is confirmed that a drawing object having a higher priority is present.
However, according to the method of creating the table by overwriting, it is possible to reduce the amount of data to be saved, but it is not possible to realize a light emission amount control operation in consideration of the overlapping state of drawing objects.

[Print output processing with emission control]
In this embodiment, when performing scanning exposure of the photoreceptor surface by an LD light source whose lighting is controlled by output image data, the drawing object is divided into divided image areas using the above-described “divided image area-drawing object correspondence table”. By controlling the light emission amount of the LD light source according to the type, the operation of reducing the extra exposure amount when the light emission amount is uniform for all the drawing objects is performed.

Specifically, for example, when the type of drawing object drawn in the divided image area is an image of an image object or a solid image of a graphic object, the exposure amount applied to these images needs to be increased, It is necessary to cope with the value of the light emission amount control value.
On the other hand, when the type of drawing object drawn in the divided image area is a character image of a character object or a line image of a graphic object, the amount of exposure applied to these images can be made smaller than that for a solid image. It is.
The light emission amount control value corresponding to the type of drawing object is determined according to the “drawing object-light emission amount control value correspondence table” prepared as described above. However, in this embodiment, for convenience of explanation, the light emission amount control value of the solid image is the largest, and the light emission amount control values of the character image and the line image are smaller than the solid image, and are regarded as the same value.

Therefore, with reference to the “divided image area-drawing object correspondence table” for a certain divided image area, the drawing condition that there is no solid image of the graphic object and the image of the character object or the line image of the graphic object, that is, the character When only an object image or a line image of a graphic object is drawn (area numbers (1) to (3), (9), (10), (13) to (15) in FIG. 5), the light emission amount control to be applied The value can be smaller than the maximum value of the solid image.
Therefore, in the divided image area in which such drawing conditions are set, compared to the conventional technique in which the entire image surface is exposed with an LD light source having a uniform light emission amount regardless of the drawing conditions, as the light emission amount control value is reduced. Consumption can be reduced.

<Print output processing flow>
Next, a processing procedure at the time of print output accompanied by the above-described light emission amount control will be described with reference to a flowchart.
FIG. 6 is a diagram showing a flow of print output processing in the printer according to the embodiment of the present invention.
When the controller 10 (FIG. 2) receives print data described in PDL (hereinafter, also referred to as “PDL data”) transmitted from the host PC 40 or the like in response to a print request, this print output process flow Start up.

When the controller 10 starts the processing flow of FIG. 6, first, the controller 10 interprets the received PDL data and sets drawing conditions including drawing commands (drawing objects and their attributes) and drawing setting information having color and transparency settings. Intermediate data to be represented is generated (step S101). Note that the processing in step S101 is performed by the PDL interpretation unit 110 (FIG. 3) in the controller 10.
Next, a “divided image region-drawing object correspondence table” (see FIG. 5) prepared for writing the drawing target data in the subsequent step S104 is created and saved in the auxiliary storage unit 13 (FIG. 3) (see FIG. 3). Step S102). As shown in FIG. 5, this table divides the entire image forming surface 50 to be drawn into 15 image areas and assigns the area numbers (1) to (15) in order to the divided image areas as a key. It has columns for object types (“character image”, “line image”, and “solid image”).

Next, based on the intermediate data generated in step S101, the controller 10 identifies the type of drawing object for each drawing object to be drawn (step S103). For each type, the drawing setting information, information on the area where the drawing object exists, and the like are written in the table prepared in step S102 (step S104).
The drawing setting information is information used for subsequent drawing processing. Further, the information on the area where the drawing object exists is information used to create the “divided image area-drawing object correspondence table” (FIG. 5). In this embodiment, the data writing process to the table of FIG. 5 is performed by examining the area numbers (1) to (15) where the type of the identified drawing object exists and drawing the table corresponding to the obtained area number. This is a process of writing “present” in the column of the object type (“character image”, “line image”, and “solid image”). Note that the processing of steps S103 and S104 is performed by the object identification unit 111 (FIG. 3).

Next, the controller 10 renders each drawing object based on the intermediate data representing the drawing conditions (drawing object type, drawing setting information, information on the area where the drawing object exists, etc.) generated in step S101. By performing processing, image data is generated as a pixel signal used for print output, and the generated image data is stored in the RAM of the main storage unit 12 (FIG. 2) or the HDD of the auxiliary storage unit 13 (FIG. 2) (step). S105). Note that the drawing processing unit 112 (FIG. 3) performs the processing in step S105.
Thereafter, it is confirmed whether or not drawing processing for all drawing objects to be drawn has been completed (step S106). If there is an unprocessed drawing object (step S106-NO), the process returns to step S103, and the unprocessed drawing object is returned. Perform the process.

  On the other hand, if the controller 10 can confirm in step S106 that all the drawing objects to be drawn have been drawn (step S106-YES), the image data for print output generated in the drawing process in step S105 is turned on. Using the “divided image region-drawing object correspondence table” created in step S104 as a control signal and using the light emission amount control signal, the LD light source is driven to expose each pixel. Control proceeds to the printer engine that forms the image.

In the present embodiment, since the photosensitive member surface is exposed by raster scanning (two-dimensional scanning by main scanning and sub scanning) with a beam emitted from the LD light source, an electrostatic latent image is formed on the photosensitive member surface. The driving of the LD light source is controlled according to the method. That is, in this embodiment, the light emission amount control value is set for each divided image area shown in FIG. 4, and the light emission amount control of the LD light source is performed according to the setting. Therefore, the main scanning and the sub scanning directions are performed in both directions. The scanning beam exiting from one divided image region to the other within the scanning line or between the main scanning lines has an operation of switching the light emission amount control when the setting of the light emission amount control value changes between these divided image regions. I need it.
As in the prior art, the lighting control of the LD light source uses the image data for print output as a control signal, and performs the lighting control in synchronization with the raster scanning, so that the image is placed at a predetermined position on the photoconductor. The operation is to form.

When an LD light source is driven to perform an image forming operation using the scanning exposure method, the divided image area on the photosensitive member surface where scanning exposure starts and the path of the divided image area that proceeds from there to the main scanning and sub-scanning directions are divided. It is determined by the area number according to the arrangement of the image areas.
That is, in the case of the divided image area shown in FIG. 4, if exposure scanning is performed in the main scanning direction and the sub-scanning direction indicated by the arrows in the figure, the area number (15) in ascending order from the area number (1). Scanning is performed according to the route determined by the area number.

  Since the scanning exposure of the divided image areas is performed in the order determined as described above, in the processing flow of FIG. 6, the controller 10 first stores the auxiliary storage unit 13 (FIG. 3) in the order of the area numbers. Read the “divided image area-drawing object correspondence table” saved in the previous procedure, and whether or not the type of the drawing object corresponding to the area number of the processing target that is the target of the subsequent light emission amount control value Is confirmed (step S107). Here, “present” or “none” indicating whether or not the types of drawing objects of “character image”, “line image”, and “solid image” are present in the divided image region is confirmed.

Next, the controller 10 determines the light emission amount control value to be set for the light emission amount control based on the presence / absence of each type of drawing object “character image”, “line image”, and “solid image” confirmed in step S107. To do.
The determination of the light emission amount control value is performed by determining the maximum value among the light emission amount control values corresponding to the respective drawing objects drawn in the divided image area, as described above in [Light emission amount control of light source corresponding to drawing condition]. By setting the light emission amount control value according to the rule of determination as the light emission amount control value to be applied to the divided image area, a desirable result can be obtained.

However, in the present embodiment using the method of determining the light emission amount control value to be set for the light emission amount control based on the presence / absence of the types of drawing objects of “character image”, “line image”, and “solid image”, further processing is performed. Since the “solid image” is a drawing object that needs to keep the light emission amount at the maximum value, it is maximized without reducing the light emission amount, and the “character image” or “line image” is the light emission amount. The processing is performed under the determination condition that the drawing object can reduce the above.
Therefore, in the processing flow of FIG. 6, the light emission amount control value is controlled to be lower than the normal level (the light emission amount is not reduced) depending on whether only “character image” or “line image” exists. It is an operation to select whether or not. In other words, if only “character image” or “line image” exists, the amount of light emission is reduced from the normal level, and for other cases, for example, when “solid image” coexists in the divided image region, the control value Control to set to normal level.

In the procedure of the processing flow of FIG. 6, after confirming the presence or absence of the type of drawing object corresponding to the region number to be processed in step S107, only “character image” or “line image” is checked from the confirmation content. It is determined whether or not it is a divided image area (step S108).
When it is determined in step S108 that the image is a divided image area in which only the “character image” or “line image” exists (step S108—YES), the light emission amount control value is set to a normal level (for the divided image area). Control is performed to make it lower than the amount of light emission is not reduced (step S109).
On the other hand, when it is determined in step S108 that there is an image other than “character image” and “line image” and it is not determined that the image is a divided image area in which only “character image” or “line image” exists (step S108—NO). For the divided image area, control is performed to set the light emission amount control value to a normal level (step S110).

Lighting control is performed on the one-divided image area to be processed using image data for print output, and the light emission amount control in step S109 or step S110 is performed to drive the LD light source to perform image formation operation by scanning exposure. When finished, it is confirmed whether or not the scanning exposure for all the divided image regions to be processed has been completed (step S111).
If scanning exposure for all the divided image areas to be processed has not been completed in step S111 (step S111-NO), there is an unprocessed divided image area, so that the process returns to step S107, and all the divided image areas are processed. The procedure from step S107 to S111 is repeated until the end.
If scanning exposure for all the divided image regions to be processed has been completed in step S111 (step S111-YES), output processing performed at a later stage such as fixing of the toner image transferred to the recording medium (paper) is performed ( Step S112), this processing flow ends.

As described above, according to the present embodiment, compared to the conventional technique in which the entire image surface is exposed with an LD light source having a uniform light emission amount according to a drawing object such as a “solid image” that cannot reduce the light emission amount. In a divided image area in which a drawing object that can reduce the light emission amount within a range that does not cause deterioration in image quality, such as a “character image” or a “line image”, is set to a small light emission amount control value. By controlling the power consumption, the amount of light emission can be reduced, so that the power consumption can be reduced compared to the prior art.
In addition, although the light emission amount control of this embodiment mentioned above showed the example controlled by the light emission amount control value set per divided image area unit, in principle, it can also be performed per pixel.

10..Controller, 11..Control unit, 12..Main storage unit, 13..Auxiliary storage unit, 15..Network I / F, 16..Output I / F, 17..Operation panel I / F, 20, 20 ₁ , 20 ₂ , 20 ₃ ..Printer, 23 ..Output device, 24 ..Operation panel, 30 ..Network, 40 ..Host PC, 110 ..PDL interpretation means, 111. 112... Drawing processing means 117... Light source drive control means 118.

JP 2011-186131 A

Claims (8)

An image forming apparatus that controls lighting of a light source based on print data and forms an image by scanning and exposing a photoconductor with light from the light source,
A light emission amount control value storage means for storing the drawing condition set in the print data and the light emission amount control value of the light source determined for each drawing condition in association with each other;
Means for acquiring a corresponding light emission amount control value from the light emission amount control value storage means based on the set drawing conditions of the print data to be processed;
A light emission amount control unit configured to control a light emission amount of the light source based on the acquired light emission amount control value; The image forming apparatus according to claim 1,
The light emission amount control means sets a maximum value among the light emission amount control values corresponding to the drawing conditions set in the print data in each divided image region obtained by dividing the image forming surface into regions of a predetermined size in each divided image region. An image forming apparatus that controls a light emission amount of a light source that is turned on in each divided image region as a light emission amount control value to be applied. The image forming apparatus according to claim 1 or 2,
The image forming apparatus, wherein the print data is described in PDL, and the drawing condition is a type of a drawing object. The image forming apparatus according to claim 3.
The light emission amount control value corresponding to the drawing condition is an image forming apparatus in which the light emission amount control value for a drawing object composed of a character or a line drawing is smaller than other drawing objects.   A non-transitory computer-readable storage medium storing a program for causing a computer to function as the light emission amount control unit included in the image forming apparatus according to claim 1.   A computer-readable recording medium on which the program according to claim 5 is recorded. An image forming apparatus according to any one of claims 1 to 4,
A host device connected to the image forming apparatus by communication means, and sending print data to the image forming apparatus by the communication means;
An image forming system comprising: A light source control method in an image forming apparatus that controls lighting of a light source based on print data and forms an image by scanning and exposing a photoconductor with light from the light source,
A storage step of associating the drawing conditions set in the print data with the emission amount control value of the light source determined for each drawing condition in the emission amount control value storage unit;
Obtaining a corresponding light emission amount control value from the light emission amount control value storage means based on the set drawing conditions of the print data to be processed;
A light emission amount control step of controlling the light emission amount of the light source based on the acquired light emission amount control value.

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