JP7341696B2 - Image forming device, image forming method and program - Google Patents

Description

The present invention relates to an image forming apparatus, an image forming method, and a program using an electrophotographic process.

2. Description of the Related Art Electrophotographic image forming apparatuses such as printers and copying machines are provided with a fixing device for thermally fixing toner images formed on paper. The target temperature required to fix a toner image varies depending on the type of paper and the toner image, and is set for each page using information (image information) that indicates how easily the toner image fixes on each page, such as printing rate. Energy saving can be achieved by setting an appropriate target temperature.
Patent Document 1 discloses a technique that achieves both energy saving and maintenance of printing productivity when the target temperature of a succeeding page is higher than that of a preceding page in continuous printing. In Patent Document 1, information on whether or not uneven gloss is likely to occur when the target temperature is increased in the preceding page is used, and if uneven gloss does not occur, the target temperature is increased in the preceding page and paper spacing is increased. The target temperature is increased to reach the desired target temperature at the start of the subsequent page.

Patent No. 5900474

In the image forming apparatus described in Patent Document 1, in the case of image information in which uneven gloss may occur when the target temperature is increased in the preceding page, the amount of increase in the target temperature within the preceding page is suppressed. In order to compensate for the suppressed increase in target temperature, the inter-sheet period is increased to increase the amount by which the target temperature is increased between sheets, thereby reaching the desired target temperature at the start of the subsequent page. As a result, a problem arises in that productivity decreases by an amount corresponding to the increased paper interval.
Therefore, an object of the invention of the present application is to provide an image forming apparatus that can determine a target temperature without increasing the paper interval.

In order to achieve the above object, the image forming apparatus of the present invention includes:
a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction ,
The acquisition unit acquires second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the second image data, the second toner image is attached to the second recording material based on the second image data. Determine the third target temperature for fixing,
The first target temperature is determined again based on the first temperature information, the second temperature information, and the third target temperature.
In order to achieve the above object, the image forming apparatus of the present invention includes:
a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The acquisition unit acquires printing rate information of second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the printing rate information, fixing the second toner image on the second recording material based on the printing rate information. Determine the fourth target temperature for
The first target temperature is determined again based on the first temperature information, the second temperature information, and the fourth target temperature.
In order to achieve the above object, the image forming apparatus of the present invention includes:
a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring the type of image in a first area and raising the temperature of the fixing unit while fixing the first recording material, the type of the image in the plurality of first areas; a plurality of pieces of first temperature information corresponding to are acquired, and the distance is an interval from the rear end of the first recording material to the leading edge of a second recording material that is transported following the first recording material in the transport direction. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between sheets;
The first temperature information is applied to the first recording material based on the plurality of first temperature information, the second temperature information, and the second target temperature for fixing the second toner image to the second recording material. determining a first target temperature that is lower than the second target temperature, which is a temperature for fixing the toner image; a determining unit that determines a first timing for raising the temperature of the fixing unit while fixing the first recording material based on the first recording material;
When fixing the first recording material, the temperature of the fixing section is raised from the first timing, and the power supplied to the fixing section is controlled based on the first target temperature, and the second recording material is fixed. If the second recording material is conveyed to the fixing unit, a control unit that controls power supplied to the fixing unit based on the second target temperature;
Equipped with
The acquisition unit acquires second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the second image data, the second toner image is attached to the second recording material based on the second image data. Determine the third target temperature for fixing,
The first target temperature is determined again based on the plurality of first temperature information, the second temperature information, and the third target temperature.
In order to achieve the above object, the image forming apparatus of the present invention includes:
a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring the type of image in a first area and raising the temperature of the fixing unit while fixing the first recording material, the type of the image in the plurality of first areas; a plurality of pieces of first temperature information corresponding to are acquired, and the distance is an interval from the rear end of the first recording material to the leading edge of a second recording material that is transported following the first recording material in the transport direction. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between sheets;
The first temperature information is applied to the first recording material based on the plurality of first temperature information, the second temperature information, and the second target temperature for fixing the second toner image to the second recording material. determining a first target temperature that is lower than the second target temperature, which is a temperature for fixing the toner image; a determining unit that determines a first timing for raising the temperature of the fixing unit while fixing the first recording material based on the first recording material;
When fixing the first recording material, increasing the temperature of the fixing section from the first timing, and
When controlling the power supplied to the fixing unit based on the first target temperature and fixing the second recording material, the second target temperature is set before the second recording material is conveyed to the fixing unit. a control unit that controls power supplied to the fixing unit based on the
Equipped with
The acquisition unit acquires printing rate information of second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the printing rate information, fixing the second toner image on the second recording material based on the printing rate information. Determine the fourth target temperature for
The method is characterized in that the first target temperature is re-determined based on the plurality of first temperature information, the second temperature information, and the fourth target temperature.

In order to achieve the above object, the image forming apparatus of the present invention includes:
a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The types of images are a character image, a halftone image, and an image other than the character image and the halftone image,
A first temperature at which the fixing section can be heated while fixing the first toner image formed according to the character image on the first recording material is determined according to the halftone image. higher than a third temperature at which the fixing unit can be heated while fixing the first toner image to be formed on the first recording material;
The third temperature may increase the temperature of the fixing unit while fixing the first toner image formed according to an image other than the character image and the halftone image on the first recording material. higher than the possible second temperature;
The first temperature information includes the first temperature, the second temperature, and the third temperature.
In order to achieve the above object, the image forming apparatus of the present invention includes:
a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The types of images are a character image, an image including the character image and a halftone image, and an image other than the character image and the halftone image,
A first temperature that can raise the temperature of the fixing unit while fixing the first toner image formed according to the character image on the first recording material is a first temperature that can increase the temperature of the fixing unit while fixing the first toner image formed according to the character image higher than a third temperature at which the temperature of the fixing unit can be raised while fixing the first toner image formed according to the image on the first recording material;
The third temperature may increase the temperature of the fixing unit while fixing the first toner image formed according to an image other than the character image and the halftone image on the first recording material. higher than the possible second temperature;
The first temperature information includes the first temperature, the second temperature, and the third temperature.

According to the present invention, it is possible to provide an image forming apparatus that can determine a target temperature without increasing the paper interval.

Schematic configuration diagram of an image forming apparatus according to the present invention A block diagram showing the system configuration of an image forming apparatus according to the present invention Flowchart for determining target fixing temperature in Example 1 Schematic diagram showing a specific example of target fixing temperature determination in Example 1 Flowchart for determining target fixing temperature in Example 2 Schematic diagram showing a specific example of target fixing temperature determination in Example 2 Flowchart for determining target fixing temperature in Example 3 Schematic diagram showing a specific example of target fixing temperature determination in Example 3

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangement of the components described in the embodiments should be changed as appropriate depending on the configuration of the device to which the invention is applied, various conditions, etc. It is not intended to limit the scope to the following embodiments.

<Example 1>
[Overall configuration of image forming apparatus]
FIG. 1 is a sectional view of the image forming apparatus of this embodiment. In this embodiment, a laser beam printer 100 (hereinafter referred to as printer 100) is shown as an example of an image forming apparatus. As shown in FIG. 1, the printer 100 includes a photosensitive drum 122 made of an organic photoreceptor or an amorphous silicon photoreceptor. The photosensitive drum 122 is rotated clockwise at a predetermined circumferential speed (process speed). The circumferential surface of the photosensitive drum 122 is uniformly charged to a predetermined polarity and potential by a charging roller 123. Then, the charged surface of the photosensitive drum 122 is irradiated with laser light output from the scanner 108, and an electrostatic latent image is formed on the photosensitive drum 122. The scanner 108 modulates (on/off converts) laser light in response to time-series digital pixel signals input from an image signal generating device (not shown) such as an image reading device or a computer. The scanning exposure start timing in the sub-scanning direction is notified from the printer 100 to the image signal generation device by a sub-scanning direction synchronization signal. An electrostatic latent image formed on the photosensitive drum 122 corresponding to a target image is developed by a developing roller 121 . In this way, a toner image is formed on the photosensitive drum 122 according to the image data.

The printer 100 is provided with a paper feed tray 140 (paper feed port) in which paper P (recording material) is placed. Paper feed roller 101 feeds paper P from paper feed tray 140 . After that, the paper P is sent to the photosensitive drum 122 by the registration roller 104, and the mirror image toner image on the photosensitive drum 122 side is transferred to the paper P, thereby forming a toner image on the paper P. The transfer roller (transfer unit) 106 transfers toner from the photosensitive drum 122 to the paper P by supplying an electric charge of opposite polarity to the toner from the back side of the paper P that is transported in the transport direction (direction indicated by arrow A in FIG. 1). Transfer the image. The paper P to which the toner image has been transferred is separated from the photosensitive drum 122 and sent to a fixing device (fixing section) 130. The fixing device 130 fixes the toner image on the paper P. The fixing device 130 includes a thermistor 131, a heater (heating section) 132, a fixing film (fixing member) 133, and a pressure roller (pressure member) 134. The paper P that has been thermally fixed is conveyed by a paper ejection roller 111 and ejected to a paper ejection tray 112 . The heater 132 heats the fixing nip N formed by the fixing film 133 and the pressure roller 134.

[System configuration of image forming apparatus]
Next, the system configuration of the printer 100 will be explained. FIG. 2 is a block diagram for explaining the system configuration of the printer 100. The printer 100 includes a controller section 201, an engine control section 202, and a video interface section 203. The controller unit 201 can communicate with the engine control unit 202 via a host computer 200, which is an external device, and a video interface unit 203.
The host computer 200 transmits print conditions, single or multiple page image data, and a print command to the controller unit 201 of the printer 100 . The controller unit 201 converts single or multiple page image data received from the host computer 200 into exposure data necessary for the printer 100, and creates print reservation information for each paper based on the received print conditions. The print reservation information includes, for example, information such as a paper feed port (such as the paper feed tray 140) indicating the supply source of the paper P, the size of the paper P, and the print mode.

The controller unit 201 includes a print rate calculation unit 220 that calculates the print rate (toner applied amount) of the target page based on image data, and a print rate calculation unit 220 that calculates the print rate (toner applied amount) of the target page based on image data, and the type of image (text, halftone, etc.) included in the target page among the plurality of pages. ). The controller unit 201 has a processor such as a CPU and a memory such as a ROM. The printing rate calculating unit 220 and the image determining unit 221 are realized by the CPU of the controller unit 201 executing a program stored in the ROM.
The printing rate calculation unit 220 receives the image data received from the host computer 200, counts the number of pixels per page forming a toner image, and calculates the printing rate of the target page. The image determination unit 221 determines whether the image indicated by the image data of each page received from the host computer 200 is a character image. There are various known methods for determining whether an image is a character image, and a detailed explanation will be omitted.
The controller unit 201 transmits a print reservation instruction to the engine control unit 202 via the video interface unit 203, including the print rate of the target page and the image determination result as to whether or not it is a character image. When the conversion from image data to exposure data is completed, the controller unit 201 transmits a print start instruction to the engine control unit 202. Upon receiving the print start instruction from the controller unit 201, the engine control unit 202 starts the print operation.

The printer 100 also includes a drum motor 204, an exposure control section 208, a drive control section 209, a high pressure control section 210, a fixing control section 211, a sensor input section 212, a fixing motor 213, and a paper feed clutch 214.
The drive control unit 209 rotates each roller of the printer 100 by controlling the drive of the drum motor 204 or the fixing motor 213. The drum motor 204 rotationally drives the paper feed roller 101 , the registration roller 104 , the photosensitive drum 122 , and the transfer roller 106 . The drum motor 204 and the paper feed roller 101 are connected via a paper feed clutch 214. When feeding paper P from the paper feed tray 140, the paper feed clutch 214 is connected for a predetermined period of time, and the paper feed roller 101 is connected to the paper feed clutch 214. 101 is driven to rotate. The fixing motor 213 rotationally drives the pressure roller 134 and the paper ejection roller 111.

The exposure control unit 208 rotates a scanner motor (not shown) provided in the scanner 108 and corrects the exposure amount in response to instructions from the engine control unit 202, and performs correction based on exposure data received from the controller unit 201. Irradiation of laser light onto the photosensitive drum 122 is controlled. The high voltage control unit 210 controls a power source that applies a DC voltage or an AC voltage to each member in the printer 100, such as the charging roller 123, the developing roller 121, and the transfer roller 106.
The fixing control unit 211 includes a target temperature determining unit 222 that determines the target temperature of the target page. The fixing control unit 211 has a processor such as a CPU and a memory such as a ROM. The target temperature determining section 222 is realized by the CPU of the fixing control section 211 executing a program stored in the ROM.
The target temperature determination unit 222 determines a target temperature for maintaining the temperature of the heater 132. The fixing control unit 211 detects the surface temperature of the heater 132 using the thermistor 131, and controls the power supply to the heater 132 so that the detected result (temperature) approaches the target temperature. That is, the fixing control unit 211 controls the power supplied to the heater 132 so that the temperature of the heater 132 is maintained at the target temperature. The fixing control section 211 is an example of a control section. Furthermore, the fixing control unit 211 may detect the temperature of the heater 132 as the temperature of the fixing device 130. The fixing control unit 211 may control the power supplied to the fixing device 130 so that the temperature of the fixing device 130 maintains the target temperature. For example, the temperature of the fixing device 130 may be controlled by the fixing control unit 211 controlling the current flowing through the fixing device 130 in accordance with a signal from the thermistor 131.
The sensor input unit 212 acquires detection information from the top sensor 105 and the fixing sheet discharge sensor 109 shown in FIG. 1, and outputs the information to the engine control unit 202.

[Image forming operation]
Next, the image forming operation of the printer 100 having the above configuration will be explained. The image forming operation is started when the engine control unit 202 receives a print start instruction from the controller unit 201.
First, in preparation for printing, the engine control unit 202 drives the drum motor 204 and the fixing motor 213. The surface of the photosensitive drum 122 is uniformly charged by the charging roller 123. The heater 132 starts to be energized as a start-up operation. When a predetermined period of time has elapsed from the start of fixing, preparation for fixing is completed, and engine control unit 202 drives paper feed clutch 214 to feed paper P from paper feed tray 140. At a predetermined timing after the leading edge of the paper P passes the top sensor 105, the engine control unit 202 outputs a digital pixel signal start signal to the controller unit 201, which is a reference timing for outputting the digital pixel signal.

The engine control unit 202 uses the scanner 108 to expose the digital pixel signal received from the controller unit 201 onto the photosensitive drum 122 to form an electrostatic latent image on the surface of the photosensitive drum 122 . Toner is supplied from the developing roller 121 to the photosensitive drum 122 , and a toner image is formed on the photosensitive drum 122 by adhering the toner to the photosensitive drum 122 . The toner image formed on the photosensitive drum 122 is transferred to the paper P. In this case, a DC voltage of opposite polarity to the toner image formed on the photosensitive drum 122 is applied to the transfer roller 106 to transfer the toner image on the photosensitive drum 122 onto the paper P.
After the paper P is peeled off from the photosensitive drum 122, it is conveyed to the fixing device 130. Then, the fixing device 130 fixes the toner image onto the paper P by passing the paper P on which the toner image has been transferred through a fixing nip N formed by the fixing film 133 and the pressure roller 134. After the toner image is fixed on the paper P, the paper P is ejected via the ejection roller 111 onto the ejection tray 112 at the top of the main body of the printer 100 with the image surface facing downward.

With the above configuration, the printing rate information calculated by the printing rate calculating unit 220 and the image determining unit 22
An embodiment of the present invention will be described in which a target temperature within a page is determined using the results determined by No. 1. In this embodiment, a method for determining the target temperature for the first page in continuous printing of A4 size plain paper will be described. In addition, in this embodiment, the printing rate and image discrimination result are determined only for the image data of the first page (preceding page), and the printing rate and image discrimination result are determined for the image data of the second and subsequent pages (subsequent page). and the image discrimination result (image information) is unknown or undetermined. In this embodiment, when continuous printing is performed, the page on which image formation is performed first is called a preceding page, and the page on which image formation is performed after image formation on the preceding page is called a subsequent page. That is, a toner image (first toner image) formed according to the image data (first image data) of the preceding page is transferred (formed) onto paper P1 (first recording material) that is conveyed in advance. . Further, a toner image (second toner image) formed according to the image data (second image data) of the subsequent page is conveyed to paper P2 (second recording material) following paper P1 (first recording material). is transferred (formed) to.

When printing on A4 size plain paper, the fixing control unit 211 can raise the temperature of the heater 132 by 5° C. during the paper interval (0.5 sec) between the preceding page and the following page. Although control of the temperature of the heater 132 will be described below, it is not limited to temperature control of the heater 132. This embodiment may be applied to temperature control of the fixing device 130. The paper interval between the preceding page and the succeeding page is defined as the distance between the paper P1 (first recording material) that is conveyed following the paper P1 from the rear end of the paper P1 (first recording material) to which the toner image (first toner image) corresponding to the image data of the preceding page has been transferred. This is the distance to the leading edge of paper P2 (second recording material). The time between the preceding page and the succeeding page is the time required for the distance from the trailing edge of the paper P1 to the leading edge of the paper P2 to pass through the fixing nip N formed by the fixing film 133 and the pressure roller 134. It's time. Hereinafter, the temperature at which the heater 132 can be heated between the sheets (or the time between sheets) between the preceding page and the succeeding page will be referred to as the inter-sheet heating temperature. Temperature information including the inter-paper heating temperature is stored in a storage unit such as a memory provided in the printer 100. The inter-paper heating temperature is set to different values depending on the inter-paper interval (or inter-paper time) between the preceding page and the subsequent page. Further, the paper interval (or the paper interval time) between the preceding page and the succeeding page differs depending on the size of the paper P and the like. The inter-paper heating temperature is a predetermined first temperature (the temperature of the heater 132 when image formation of the subsequent page is started) to a predetermined second temperature (the temperature of the heater 132 after the image formation of the preceding page is completed). It can be determined by subtraction.
The target temperature determining unit 222 determines a target temperature according to the printing rate information calculated by the printing rate calculating unit 220. For example, the table shown in Table 1 is stored in a storage unit such as a memory provided in the printer 100, and the target temperature determination unit 222 refers to the table stored in the storage unit when determining the target temperature. Good too. Further, the target temperature determining unit 222 determines the determined target temperature as the lowest temperature at which the toner image can be fixed.

The image determination unit 221 divides the image data of the target page among the plurality of pages into two or more regions along the conveyance direction of the paper P (hereinafter simply referred to as the conveyance direction). Further, the image determining unit 221 determines whether the image of each of the plurality of regions is only a character image, and transmits determination information that is the determination result to the target temperature determining unit 222. In other words, the image determining unit 221 determines the image types of the plurality of divided areas, and transmits the image types of each area to the target temperature determining unit 222. If the image included in a given area of the image data is only a character image, even if the temperature of the heater 132 (fixing temperature) is raised while the character image is being fixed on the paper P, uneven density or uneven gloss may occur. No uneven fixing occurs. Therefore, the target temperature determination unit 222 determines that it is possible to raise the temperature of the heater 132 during the fixing process (during fixing) of the area that includes only the character image among the multiple areas of the image data of the target page. That is, the target temperature determination unit 222 determines that it is possible to raise the temperature of the heater 132 while the toner image formed according to the character image is being fixed on the paper P. Hereinafter, the area where the temperature of the heater 132 can be increased during the fixing process among the multiple areas of the image data of the target page will be referred to as the area where the temperature can be increased. Furthermore, among the plurality of regions of the image data of the target page, the region in which the temperature of the heater 132 cannot be increased during the fixing process is referred to as the region in which the temperature cannot be increased. In this embodiment, the temperature of the heater 132 within the temperature increase possible range can be increased within a range of 10°C. Therefore, the target temperature determination unit 222 can increase the target temperature of the temperature increaseable region by a maximum of 10 degrees Celsius. The heating temperature of the heater 132 (fixing temperature raising amount) within the temperature raising possible region may be a value other than 10°C.
The image determination unit 221 obtains 10° C. as the heating temperature of the heater 132 for the region where the temperature can be raised among the plurality of divided regions. In addition, the image discrimination unit 221 acquires information indicating that the heating temperature of the heater 132 is 0° C. or that the heating of the heater 132 is impossible for a region in which heating is not possible among the plurality of divided regions. .

Next, the operation of the target temperature determining unit 222 determining the target temperature will be described using a flowchart, and then a specific application example will be described.
FIG. 3 is a flowchart showing the operation of the target temperature determination unit 222 (hereinafter referred to as determination unit 222) to determine the target temperature. The determining unit 222 sets the target temperature (T_1) of the leading edge (downstream end in the transport direction) of the paper P corresponding to the subsequent page to the maximum temperature value in Table 1 (S301). This is because information such as the print rate and image discrimination results of the subsequent page is unknown at the time the target temperature of the preceding page, which is the target page, is determined, so any image can be fixed without reducing productivity. This is to make it possible. Here, the paper P corresponding to the subsequent page means the paper P on which the image of the subsequent page is printed. Hereinafter, the leading edge of the paper P corresponding to the subsequent page will be referred to as the leading edge of the paper P of the subsequent page, and the trailing edge (the upstream end in the transport direction) of the paper P corresponding to the subsequent page will be referred to as the trailing edge of the paper P of the subsequent page. call. Next, the determining unit 222 determines the minimum target temperature (T_min) from Table 1 based on the print rate information of the target page transmitted from the controller unit 201 (S302). That is, the determination unit 222 determines the minimum target temperature (T_min) of the target page based on the print rate information of the target page. continue,
The determination unit 222 determines the target temperature (T_t) of the trailing edge of the paper of the target page from the target temperature (T_1) of the leading edge of the paper of the subsequent page and the temperature increase temperature (T_g) of the paper using the following equation (1). S3
03).
T_t = T_1 - T_g...(1)
However, if T_t<T_min, T_t=T_min.

The image determination unit 221 divides the target page into a plurality of regions along the transport direction. The determining unit 222 determines the region at the rearmost end of the target page as region n among the regions obtained by dividing the target page in the transport direction (S304). The determining unit 222 determines the larger value between the target temperature (T_t) of the trailing edge of the paper of the target page (the trailing edge of the paper P corresponding to the target page) and the minimum target temperature (T_min) as the target temperature of area n. (S305). Next, in order to determine the target temperature of the area ahead of the area n at the rearmost edge of the areas divided in the conveyance direction, the determination unit 222 determines the target temperature of the area one area ahead of the area n at the rearmost edge of the target page. The area is determined as area n-1 (S306). That is, the determination unit 222 determines a region adjacent to region n and located downstream of region n in the conveyance direction as region n-1, and uses region n-1 as the target temperature for which the target temperature is determined. Determine the area.

The determining unit 222 determines whether or not the temperature of the heater 132 can be increased during the fixing process for the area n at the rear end of the target page (S307). Specifically, the determining unit 222 determines whether the image of area n transmitted from the controller unit 201 is a character image. If the image in area n is a character image, the determining unit 222 determines that the temperature of the heater 132 can be raised during the fixing process for area n, and if the image in area n is not a character image, the determination unit 222 determines that the temperature of the heater 132 can be increased during the fixing process for area n. It is determined that it is impossible to raise the temperature of the heater 132 during processing. If it is possible to raise the temperature of the heater 132 during the fixing process for area n, there is a possibility that the target temperature for area n-1 may be lower than the target temperature for area n. The determining unit 222 determines the larger value of the minimum target temperature (T_min) and the temperature obtained by subtracting the heating temperature of the heater 132 (for example, 10° C.) from the target temperature of region n as the target temperature of region n-1. (S308). If it is impossible to raise the temperature of the heater 132 during the fixing process for area n, the temperature of the heater 132 must not be increased during the fixing process for area n. Therefore, the determining unit 222 determines the target temperature of region n-1 to be the same as the target temperature of region n (S309).

The determining unit 222 repeats the above processing of S307, S308, or S309 up to the most advanced region of the target page (S310 and S311), and determines the target temperature of each region within the target page. Note that in S310, the determining unit 222 determines whether area n-1 is the most advanced area of the target page. In S311, the determination unit 222 determines a region one region ahead of region n-1 on the downstream side in the transport direction as region n-2. That is, the determining unit 222 determines region n-2 as the target region for determining the target temperature. The determining unit 222 determines area n-2, area n-3, . . . each time the processes of S307, S308, and S309 are repeated, and Perform the same processing as n-1.

An example of the processing of the image discriminating section 221 and the processing of the determining section 222 in the first embodiment will be shown below. The image determination unit 221 divides the image data (first image data) of the target page among the plurality of pages into a plurality of regions along the transport direction. The first image data corresponds to a toner image (first toner image) formed on paper P1 (first recording material) that is conveyed in advance. The image determination unit 221 determines, based on the first image data, the temperature of the heater 132 during the fixing process on the paper P1 (first recording material) of each first toner image formed according to the images of the plurality of divided areas. A plurality of first temperature information including temperature is acquired. The image discrimination section 221 and the determination section 222 are examples of an acquisition section. The image determination unit 221 or the determination unit 222 acquires second temperature information including the paper interval temperature increase (T_g) from a storage unit such as a memory provided in the printer 100. The determining unit 222 fixes each first toner image formed according to the images of the plurality of regions onto the paper P1 based on the plurality of first temperature information, second temperature information, and second target temperature. each first target temperature corresponding to each first toner image is determined. The second target temperature is a target temperature for fixing the second toner image formed according to the image data of the subsequent page following the target page onto the paper P2 (second recording material). The first target temperature is lower than the second target temperature. The fixing control unit 211 maintains the temperature of the heater 132 at each first target temperature corresponding to each first toner image when each toner image transferred to the paper P1 passes through the fixing nip N. The power supplied to the heater 132 is controlled. That is, when fixing the paper P1, the fixing control unit 211 controls the power supplied to the heater 132 so that the temperature of the heater 132 maintains each first target temperature corresponding to each first toner image. On the other hand, when fixing the paper P2, the fixing control unit 211 controls the power supplied to the heater 132 so that the temperature of the heater 132 reaches the second target temperature before the paper P2 is conveyed to the fixing device 130. .

A specific example of determining the target temperature based on the flow shown in FIG. 3 will be described using the schematic diagram shown in FIG. 4. The horizontal axis of FIG. 4 is time, and the vertical axis of FIG. 4 is target temperature (° C.), and FIG. 4 shows how the target temperature changes with elapsed time. Furthermore, the diagram at the bottom of the graph in FIG. 4 shows the time during which each area in the page divided into a plurality of areas is subjected to the fixing process (the time for passing through the fixing nip portion N). In the specific example in Figure 4, the page is divided into four areas along the conveyance direction (direction indicated by arrow A in Figure 4), the printing rate for the entire page is 5%, and the image discrimination results and temperature rise for each area. Information on whether or not it is possible is as shown in Table 2. Further, regions 4, 3, 2, and 1 are arranged in the order from the page end on the upstream side in the transport direction to the page end on the downstream side in the transport direction. In this embodiment, an example is shown in which a page is divided into equal regions, but the areas of the divided regions may be different for each region.

With reference to FIGS. 3 and 4, the target temperature determination process for the target page will be described. The paper heating temperature (T_g) is 5°C. The heating temperature of the heater 132 during the fixing process of the toner images formed according to the images of areas 1 to 3 on the paper P (hereinafter referred to as the heating temperature during the fixing process) is 10°C. The temperature increase during the fixing process in region 4 is 0°C. Since the reservation information for the subsequent page is unknown, the target temperature (T_1) of the leading edge of the paper for the subsequent page is 200° C. based on Table 1 (S301, T400). The printing rate of the target page is 5%, and the minimum target temperature (T_min) is 180° C. based on Table 1 (S302). The target temperature (T_t) of the trailing edge of the paper of the target page is 195° C. (=200° C.-5° C.) (S303). Subsequently, the larger temperature (195°C) of T_t (195°C) and T_min (180°C) is determined as the target temperature for region 4 (S305, T401). According to Table 2, since area 4 is not a character image and it is impossible to raise the temperature of the heater 132, the target temperature for area 3 is determined to be the same value (195°C) as the target temperature for area 4 (195°C). (S306, S307, S309, T402). Subsequently, a target temperature for region 2 is determined (S310, S311). According to Table 2, region 3 is a character image, and the temperature of the heater 132 can be increased in region 3. Therefore, the target temperature of region 2 is determined to be the larger of the target temperature of region 3 (195 °C) - 10 °C = 185 °C and T_min (180 °C) (185 °C) (S307, S308, T403 ). Finally, the target temperature for region 1 is determined (S310, S311). From Table 2, region 2 is a character image and the temperature of the heater 132 can be increased, so the target temperature of region 1 is the target temperature of region 2 (185°C) - 10°C = 175°C and T_min (180°C) The larger temperature (180° C.) is determined (S307, S308, T404).

As shown in FIG. 4, the target temperatures in regions 1 to 4 increase from the end of the page on the downstream side in the transport direction to the end of the page on the upstream side in the transport direction. Regions 1 to 4 are composed of a first image region (regions 1 to 3) containing character images and a second image region (region 4) containing images other than character images. The temperature increase during the fixing process for areas 1 to 3 is 10°C. The heating temperature during the fixing process in area 4 is 0°C. In this way, the temperature increase (10° C.) during the fixing process in areas 1 to 3 is higher than the temperature increase (0°C) during the fixing process in area 4. The heating temperature during the fixing process in areas 1 to 3 is such that the temperature of the heater 132 is raised while the first toner image formed according to the character image is being fixed on the paper P1 (first recording material). This is the first possible temperature. The temperature increase during the fixing process in area 4 is determined by heating the heater 132 while fixing the first toner image formed according to the image other than the character image (halftone image) onto the paper P1 (first recording material). This is the second temperature at which it is possible to raise the temperature.
As shown in FIG. 4, for adjacent areas 1 and 2, the difference (5°C) between the target temperature of area 1 (180°C) and the target temperature of area 2 (185°C) is The temperature is below the temperature increase during processing (10°C). Furthermore, as shown in Figure 4, for the adjacent regions 2 and 3, the difference (10 °C) between the target temperature of region 2 (185 °C) and the target temperature of region 3 (195 °C) is The temperature is lower than the temperature raised during the fixing process (10° C.).

Another example of the processing of the image discriminating unit 221 and the processing of the determining unit 222 in the first embodiment will be shown below. The image determination unit 221 divides the image data (first image data) of a target page among the plurality of pages into a plurality of first regions along the transport direction. The image determining unit 221 determines or obtains the types of images of the plurality of divided first regions based on the first image data. In other words, the image determining unit 221 determines or obtains the type of image for each of the plurality of first regions based on the first image data. Based on the first image data, the image determining unit 221 determines whether each first toner image formed according to the images of the plurality of divided first areas is being fixed (during fixing) on the paper P1 (first recording material). A plurality of pieces of first temperature information including the temperature increase of the heater 132 is acquired. The plurality of pieces of first temperature information correspond to the types of images of the plurality of first regions. That is, each piece of first temperature information corresponds to the type of image determined for each of the plurality of first regions. The image determination unit 221 or the determination unit 222 acquires second temperature information including the paper interval temperature increase (T_g) from a storage unit such as a memory provided in the printer 100. The determining unit 222 includes a plurality of pieces of first temperature information and a second temperature information.
Based on the temperature information and the second target temperature, each first toner image corresponding to each first toner image to fix each first toner image formed according to the images of the plurality of first areas onto the paper P1. 1. Determine the target temperature. The first target temperature is lower than the second target temperature. The determining unit 222 determines the timing (first timing) for increasing the temperature of the heater 132 during the fixing process of the paper P1, based on the types of images in the plurality of first areas and the plurality of first target temperatures. . The determining unit 222 may determine one first timing or a plurality of first timings. In the example shown in FIG. 4, the determining unit 222 determines to raise the temperature of the heater 132 (temperature increase timing) during the fixing process of the paper P1 for areas 2 and 3. The fixing control unit 211 controls the temperature of the heater 132 to maintain each first target temperature corresponding to each first toner image when each first toner image transferred to the paper P1 passes through the fixing nip N. In addition, the power supplied to the heater 132 is controlled. That is, when fixing the paper P1, the fixing control unit 211 controls the power supplied to the heater 132 so that the temperature of the heater 132 increases from each first timing and the temperature of the heater 132 maintains each first target temperature. control. On the other hand, when fixing the paper P2, the fixing control unit 211 controls the power supplied to the heater 132 so that the temperature of the heater 132 reaches the second target temperature before the paper P2 is conveyed to the fixing device 130. .

As described above, in this embodiment, even if the image data of the subsequent page is unknown, the target temperature is lowered as much as possible based on the printing rate of the target page and information on whether it is a character image or not. Then, in preparation for a case where the printing rate of the subsequent page is high, the target temperature of the target page is changed to be raised stepwise for each divided area. Specifically, for each of the divided regions, the target temperature is raised in stages from the end of the target page on the downstream side in the transport direction toward the end of the target page on the upstream side in the transport direction. That is, the target temperature of each region increases stepwise from the downstream side to the upstream side in the transport direction. As a result, there is no need to increase the time between sheets in order to perform the fixing process on the subsequent page, so printing can be performed without reducing productivity. As a result, the energy saving of the printer 100 (image forming apparatus) can be improved without reducing productivity.

<Example 2>
In Example 1, the printing rate and image discrimination result are determined only for the first page (preceding page), and the printing rate and image discrimination result of the image data of the second and subsequent pages (subsequent page) are unknown or undetermined. The method for determining the target temperature for the first page in the case has been explained. That is, in the first embodiment, a method has been described in which the target temperature of the first page is determined when the determination unit 222 acquires image data for each page. In the second embodiment, a method of re-determining the target temperature of the preceding page when image data of the succeeding page is acquired will be described. Specifically, in continuous printing of A4 size plain paper, the target temperature for the first page has already been determined by the method described in Example 1, and when the image data for the second page is acquired, the target temperature for the first page is A case where the target temperature is re-determined will be explained. In this embodiment as well, the relationship between the printing rate and the target temperature is based on Table 1, and the image discrimination results for both the first and second pages are based on Table 2. Further, similar to the first embodiment, this embodiment may be applied to temperature control of the fixing device 130.

FIG. 5 is a flowchart showing the operation in which the determining unit 222 determines the target temperature. The determining unit 222 determines the target page for determining the target temperature to be the last page among the plurality of pages for which image data has been acquired (S501). Here, the final page corresponds to the second page. There are no pages after the final page, and the reservation information for subsequent pages is unknown. Therefore, similarly to S301 of the first embodiment, the determining unit 222 determines the target temperature (T_1) of the leading edge of the paper of the subsequent page.
) is set to the maximum temperature value in Table 1 (S502). Thereafter, the target temperature of the target page (second page) is determined by performing the same processing as S302 to S311 of the first embodiment (S503). Next, the determining unit 222 checks whether the adjacent page (first page), which is the page immediately before the final page, has undergone the fixing process (S504), and if the fixing process has not been completed, the determining unit 222 selects the target page for which the target temperature is to be determined. is determined to be the adjacent page (first page) (S505). The determining unit 222 determines the target temperature of the target page (first page) determined in S505 by performing the same processing as in S302 to S311 of the first embodiment (S503). If the adjacent page (first page) has already undergone the fixing process, there is no need to re-determine the target temperature, so the target temperature determination flow is ended. In this way, the determination unit 222 determines the last page of the plurality of pages as the target page, and determines the target temperatures for the plurality of pages in descending order from the last page.

FIG. 6 is a schematic diagram similar to FIG. 4 illustrating a specific example in which the target temperature is determined based on the flow shown in FIG. In this embodiment, the image data of the second page is the same as that of the first page, and the image information (print rate of image data and image discrimination result) of the second page is the same. Therefore, the flow of determining the target temperature for the second page (processing of S501 to S503 and T600 to T604) is the same as T400 to T404 in FIG. be. Based on this result, the target temperature (T_1) for the leading edge of the paper on the second page is 180°C (minimum target temperature (T_min)), so the target temperature for the trailing edge of the paper on the first page is 180°C based on equation 1. It is ℃. Therefore, the target temperature of each area in determining the target temperature for the first page is 180°C (T_min) in all areas according to S503, and by recalculating using the target temperature of the leading edge of the paper for the subsequent page, the target temperature for the first page is can determine a lower target temperature.
As explained above, according to this embodiment, when the image data of the subsequent page is acquired, the target temperature of the preceding page is recalculated in descending order from the last page, so that the target temperature can be adjusted for each page. It becomes possible to determine a lower target temperature than in the case where the target temperature is determined.

An example of the processing of the image discriminating section 221 and the processing of the determining section 222 in the second embodiment will be shown below. The image determination unit 221 acquires image data (second image data) of the subsequent page. If the fixing process for the image data of the preceding page (first image data) on paper P1 has not been completed at the time when the image determining unit 221 acquires the second image data, the determining unit 222 determines that the second image data Based on this, the third target temperature is determined. The third target temperature is for fixing the second toner image formed according to the image data (second image data) of the subsequent page following the target page (preceding page) onto the paper P2 (second recording material). This is the target temperature. The determining unit 222 determines the third target temperature using the same process as the first target temperature determination process in the first embodiment. The determining unit 222 fixes each first toner image formed according to the images of the plurality of regions onto the paper P1 based on the first temperature information, the second temperature information, and the third target temperature. re-determine each first target temperature corresponding to each first toner image. The first target temperature is lower than the third target temperature. The first temperature information and the second temperature information are the same as in the first embodiment.
Furthermore, if the fixing process for the paper P1 is not completed at the time when the image determining unit 221 acquires the printing rate information of the second image data, the determining unit 222 determines, based on the printing rate information of the second image data, A fourth target temperature may be determined. For example, the determining unit 222 may refer to the table shown in Table 1 of the first embodiment and determine the fourth target temperature based on the printing rate information of the second image data. The determining unit 222 fixes each first toner image formed according to the images of the plurality of regions onto the paper P1 based on the first temperature information, the second temperature information, and the fourth target temperature. Each first target temperature corresponding to each first toner image may be re-determined.

<Example 3>
In the first embodiment, the result discriminated by the image discriminating unit 221 is the result of whether or not it is a text image, and depending on the result, it is possible to increase the temperature by 10°C in the area containing only the text image, and to increase the temperature in other areas. It has been decided that it is impossible to raise the temperature. In this embodiment, in addition to determining whether or not a character image is included, the image determination unit 221 determines whether or not a halftone image (dot image) is included, and the temperature increase of the heater 132 is determined according to the result. The configuration for determining this will be explained. Further, like the first and second embodiments, this embodiment may be applied to temperature control of the fixing device 130.

Since an image is formed by a group of isolated dots in an area including a halftone image, fixing unevenness such as density unevenness and gloss unevenness that occurs when the temperature (heat amount) of the heater 132 is increased is less likely to occur in an area including a solid image. It is difficult to see compared to the case. Therefore, in this example, the target temperature increase value in the area including the halftone image is set to 5°C, which is a value lower than the 10°C adopted in the case of only the character image, thereby preventing the occurrence of fixing unevenness. . When each area of image data contains only a character image (including no printing) (Case A), only a halftone image, or a halftone image and a character image (Case B), cases other than these (Case In C), the heating temperature of the heater 132 is determined based on Table 3.

FIG. 7 is a flowchart showing the operation in which the determining unit 222 determines the target temperature. The processing from S701 to S706 for determining the minimum target temperature (T_min) of the target page and the target temperature of the trailing edge of paper (T_t) of the subsequent page is the same as the processing from S301 to S306 in FIG. 3. The explanation will be omitted, and the explanation will be given below starting from the process of S707.

The determining unit 222 checks the image discrimination result of the area n transmitted from the controller unit 201, and determines whether or not it is possible to raise the temperature of the heater 132 during the fixing process of the area n at the rear end of the target page based on Table 3. (S707). Specifically, the determining unit 222 determines the temperature increase of the heater 132 in the region n transmitted from the controller unit 201 based on the three cases shown in Table 3. If the heating temperature of the heater 132 in the region n is not 0° C., the determining unit 222 determines that the temperature of the heater 132 can be raised during the fixing process in the region n. If the heating temperature of the heater 132 in the region n is 0° C., the determining unit 222 determines that it is impossible to raise the temperature of the heater 132 during the fixing process in the region n. If it is possible to raise the temperature of the heater 132 during the fixing process for area n, there is a possibility that the target temperature for area n-1 may be lower than the target temperature for area n. The determining unit 222 determines the larger value of the minimum target temperature (T_min) and the temperature obtained by subtracting the heating temperature of the heater 132 (for example, 10° C.) from the target temperature of region n as the target temperature of region n-1. (S708). If it is impossible to raise the temperature of the heater 132 during the fixing process for area n, the temperature of the heater 132 must not be increased during the fixing process for area n. Therefore, the decision section 2
22 determines the target temperature of region n-1 to be the same as the target temperature of region n (S709).

The determining unit 222 repeats the above processing of S707, S708, or S709 up to the most advanced region of the target page (S710 and S711), and determines the target temperature of each region within the target page. Note that in S710, the determining unit 222 determines whether area n-1 is the most advanced area of the target page. In S711, the determination unit 222 determines an area one area ahead of area n-1 in the transport direction of paper P as area n-2. That is, the determining unit 222 determines region n-2 as the target region for determining the target temperature. The determining unit 222 determines area n-2, area n-3, . . . each time the processes of S707, S708, and S709 are repeated, and Perform the same processing as n-1.

FIG. 8 is a schematic diagram similar to FIG. 4 illustrating a specific example in which the target temperature is determined based on the flow shown in FIG. In the specific example shown in FIG. 8, the page is divided into four areas in the transport direction, and the printing rate for the entire page is 5%. The image discrimination results for each area and information on the temperature increase of the heater 132 are shown in Table 4. As shown. In this embodiment, an example is shown in which a page is divided into equal regions, but the areas of the divided regions may be different for each region.

Referring to FIGS. 7 and 8, the target temperature determination process for the target page will be described. The paper heating temperature (T_g) is 5°C. The temperature increase during the fixing process in areas 1 and 2 is 10°C. The temperature increase during the fixing process in region 3 is 0°C. The temperature increase during the fixing process in region 4 is 5°C. Since the reservation information for the subsequent page is unknown, the target temperature of the leading edge of the paper for the subsequent page (T_1)
is 200°C based on Table 1 (S701, T800). The printing rate of the target page is 5%, and the minimum target temperature (T_min) is 180° C. based on Table 1 (S702). The target temperature (T_t) of the trailing edge of the paper of the target page is 195°C (=200°C - 5°C) (S703)
. Subsequently, the larger temperature (195°C) of T_t (195°C) and T_min (180°C) is determined as the target temperature for region 4 (S705, T801). According to Table 4, the image discrimination result for region 4 is case B (halftone image only or character image and halftone image included). Therefore, it is possible to raise the temperature of the heater 132 for region 4, and the target fixing temperature for region 3 is the larger temperature (190°C) between 190°C (=195°C - 5°C) and T_min (180°C). It is determined. (S706, S707, S708, T802). Subsequently, the target temperature for region 2 is determined (S710, S711). From Table 4, the image discrimination result for region 3 is case C (other than character images and halftone images), and for region 3, it is impossible to raise the temperature of the heater 132. Therefore, the target temperature of region 2 is determined to be the same value (190° C.) as the target temperature (190° C.) of region 3 (S706, S707, S709, T803). Finally, the target temperature for region 1 is determined (S710, S711). According to Table 4, region 2 is a character image, and the temperature of the heater 132 can be increased (10° C.). Since the target temperature of region 2 (190°C) - 10°C = 180°C is the same as the temperature of T_min (180°C), the target temperature of region 1 is 1
The temperature is determined to be 80°C (S707, S708, T804).

As shown in FIG. 8, the target temperatures in regions 1 to 4 are set from the edge of the page on the downstream side in the conveyance direction (direction indicated by arrow A in FIG. 8) to the edge of the page on the upstream side in the conveyance direction. It's getting expensive. Areas 1 to 4 are a first image area (area 1, 2) containing a character image, a second image area (area 4) containing a halftone image, and an image other than the character image and halftone image (for example, a solid image). ) and a third image area (area 3). The temperature increase during the fixing process for areas 1 and 2 is 10°C, the temperature increase during the fixing process for area 3 is 0°C, and the temperature increase during the fixing process for area 4 is 5°C. In this way, the temperature increase (10° C.) during the fixing process in areas 1 and 2 is higher than the temperature increase (5° C.) during the fixing process in area 4. Further, the temperature increase during the fixing process in area 4 (5° C.) is higher than the temperature increase during the fixing process in area 3 (0° C.). The heating temperature during the fixing process in areas 1 and 2 is such that the temperature of the heater 132 is raised while the first toner image formed according to the character image is being fixed on the paper P1 (first recording material). This is the first possible temperature. The temperature increase during the fixing process in area 4 can increase the temperature of the heater 132 while the first toner image formed according to the halftone image is being fixed on the paper P1 (first recording material). This is the third temperature. The temperature increase during the fixing process in area 3 fixes the first toner image formed according to an image other than a character image and a halftone image (for example, a solid image) onto the paper P1 (first recording material). This is the second temperature at which the heater 132 can be heated during this period.

Areas 1 to 4 are a first image area (areas 1, 2) containing character images, a second image area (area 4) containing character images and halftone images, and images other than character images and halftone images (areas 1 and 2). For example, a third image area (area 3) including a solid image) may be configured. In this case, similarly to the above, the temperature increase during the fixing process for areas 1 and 2 is 10°C, the temperature increase during the fixing process for area 3 is 0°C, and the temperature increase during the fixing process for area 4 is 10°C. The temperature was 5°C. In this way, the temperature increase (10° C.) during the fixing process in areas 1 and 2 is higher than the temperature increase (5° C.) during the fixing process in area 4. Further, the temperature increase during the fixing process in area 4 (5° C.) is higher than the temperature increase during the fixing process in area 3 (0° C.). The heating temperature during the fixing process in areas 1 and 2 is such that the temperature of the heater 132 is raised while the first toner image formed according to the character image is being fixed on the paper P1 (first recording material). This is the first possible temperature. The temperature increase during the fixing process in area 4 is such that the heater 132 is turned on while the first toner image formed according to the image including the character image and the halftone image is being fixed on the paper P1 (first recording material). This is a third temperature that can be increased. The temperature increase during the fixing process in area 3 fixes the first toner image formed according to an image other than a character image and a halftone image (for example, a solid image) onto the paper P1 (first recording material). This is the second temperature at which the heater 132 can be heated during this period.

As explained above, in this embodiment, even if the image information of the subsequent page is unknown or undetermined, the image determination unit 221 uses the print rate of the target page and the type of character image or halftone to determine whether the image information is unknown or undetermined. , lower the target temperature as much as possible. Then, in preparation for a case where the printing rate of the subsequent page is high, the target temperature of the target page is changed to be raised stepwise for each divided area. Specifically, for each of the divided regions, the target temperature is raised in stages from the end of the target page on the downstream side in the transport direction toward the end of the target page on the upstream side in the transport direction. As a result, there is no need to increase the time between sheets in order to perform the fixing process on the subsequent page, so printing can be performed without reducing productivity. As a result, the energy saving of the printer 100 (image forming apparatus) can be improved without reducing productivity.
In this embodiment, the image determining unit 221 determines whether the image includes a character image or a halftone, and determines the temperature to be heated to the heater 132 according to the result. As another configuration, the image discriminating section 221 may be configured to discriminate various types such as graphics, and specify the fixing temperature increase amount according to the results.

(Other examples)
The present invention provides a system or device with a program that implements one or more of the functions of Embodiments 1 to 3 via a network or storage medium, and one or more processors in the computer of the system or device reads the program. It can also be realized by executing processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Further, each process in Examples 1 to 3 may be realized by a method (image forming method) in which a computer executes the program. The program may be provided to the computer via a network or from a computer-readable recording medium that non-temporarily stores data, for example. The above program may be recorded on a computer-readable recording medium.

130... Fixing device, 132... Heater, 211... Fixing control section, 221... Image discriminating section, 222... Target temperature determining section

Claims (7)

a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The acquisition unit acquires second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the second image data, the second toner image is attached to the second recording material based on the second image data. Determine the third target temperature for fixing,
An image forming apparatus characterized in that the first target temperature is re-determined based on the first temperature information, the second temperature information, and the third target temperature. a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The acquisition unit acquires printing rate information of second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the printing rate information, fixing the second toner image on the second recording material based on the printing rate information. Determine the fourth target temperature for
An image forming apparatus characterized in that the first target temperature is re-determined based on the first temperature information, the second temperature information, and the fourth target temperature. a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring the type of image in a first area and raising the temperature of the fixing unit while fixing the first recording material, the type of the image in the plurality of first areas; a plurality of pieces of first temperature information corresponding to are acquired, and the distance is an interval from the rear end of the first recording material to the leading edge of a second recording material that is transported following the first recording material in the transport direction. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between sheets;
The first temperature information is applied to the first recording material based on the plurality of first temperature information, the second temperature information, and the second target temperature for fixing the second toner image to the second recording material. determining a first target temperature that is lower than the second target temperature, which is a temperature for fixing the toner image; a determining unit that determines a first timing for raising the temperature of the fixing unit while fixing the first recording material based on the first recording material;
When fixing the first recording material, the temperature of the fixing section is raised from the first timing, and the power supplied to the fixing section is controlled based on the first target temperature, and the second recording material is fixed. If the second recording material is conveyed to the fixing unit, a control unit that controls power supplied to the fixing unit based on the second target temperature;
Equipped with
The acquisition unit acquires second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the second image data, the second toner image is attached to the second recording material based on the second image data. Determine the third target temperature for fixing,
An image forming apparatus characterized in that the first target temperature is re-determined based on the plurality of first temperature information, the second temperature information, and the third target temperature. a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring the type of image in a first area and raising the temperature of the fixing unit while fixing the first recording material, the type of the image in the plurality of first areas; a plurality of pieces of first temperature information corresponding to are acquired, and the distance is an interval from the rear end of the first recording material to the leading edge of a second recording material that is transported following the first recording material in the transport direction. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between sheets;
The first temperature information is applied to the first recording material based on the plurality of first temperature information, the second temperature information, and the second target temperature for fixing the second toner image to the second recording material. determining a first target temperature that is lower than the second target temperature, which is a temperature for fixing the toner image; a determining unit that determines a first timing for raising the temperature of the fixing unit while fixing the first recording material based on the first recording material;
When fixing the first recording material, the temperature of the fixing section is raised from the first timing, and the power supplied to the fixing section is controlled based on the first target temperature, and the second recording material is fixed. If the second recording material is conveyed to the fixing unit, a control unit that controls power supplied to the fixing unit based on the second target temperature;
Equipped with
The acquisition unit acquires printing rate information of second image data corresponding to the second toner image,
The determining unit is
If fixing of the first recording material is not completed at the time when the acquisition unit acquires the printing rate information, fixing the second toner image on the second recording material based on the printing rate information. Determine the fourth target temperature for
An image forming apparatus characterized in that the first target temperature is re-determined based on the plurality of first temperature information, the second temperature information, and the fourth target temperature. The types of the images are a character image and an image other than the character image,
A first temperature that can raise the temperature of the fixing unit while fixing the first toner image formed in accordance with the character image on the first recording material is set to higher than a second temperature at which the fixing unit can be heated while fixing the first toner image formed in accordance with the first toner image on the first recording material;
5. The image forming apparatus according to claim 1, wherein the first temperature information includes the first temperature and the second temperature. a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. record
a control unit that controls power supplied to the fixing unit based on the second target temperature before the material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The types of images are a character image, a halftone image, and an image other than the character image and the halftone image,
A first temperature at which the fixing section can be heated while fixing the first toner image formed according to the character image on the first recording material is determined according to the halftone image. higher than a third temperature at which the fixing unit can be heated while fixing the first toner image to be formed on the first recording material;
The third temperature may increase the temperature of the fixing unit while fixing the first toner image formed according to an image other than the character image and the halftone image on the first recording material. higher than the possible second temperature;
The image forming apparatus is characterized in that the first temperature information includes the first temperature, the second temperature, and the third temperature. a fixing unit that fixes a toner image formed according to the image data to a recording material;
Based on the first image data corresponding to the first toner image formed on the first recording material that is conveyed in advance, the first image data is divided into a plurality of pieces along the sub-scanning direction that is the conveyance direction of the recording material. first temperature information capable of acquiring an image type of an area and raising the temperature of the fixing unit while fixing the first recording material, the first temperature information corresponding to the image type of the plurality of areas; First temperature information is acquired for each of the plurality of regions, and in the conveying direction, the interval is from the rear end of the first recording material to the leading edge of a second recording material that is conveyed following the first recording material. an acquisition unit that acquires second temperature information capable of increasing the temperature of the fixing unit between certain sheets;
The first temperature information is applied to the first recording material based on the first temperature information, the second temperature information, and a second target temperature for fixing the second toner image formed on the second recording material. a determining unit that determines for each of the plurality of regions a first target temperature that is lower than the second target temperature that is a temperature for fixing the toner image;
When fixing the first recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas, and when fixing the second recording material, the power supplied to the fixing section is controlled based on the first target temperature determined for each of the plurality of areas. a control unit that controls power supplied to the fixing unit based on the second target temperature before the recording material is conveyed to the fixing unit;
Equipped with
The first target temperature determined for each of the plurality of regions increases from the downstream side to the upstream side in the sub-scanning direction,
The types of images are a character image, an image including the character image and a halftone image, and an image other than the character image and the halftone image,
A first temperature that can raise the temperature of the fixing unit while fixing the first toner image formed according to the character image on the first recording material is a first temperature that can increase the temperature of the fixing unit while fixing the first toner image formed according to the character image higher than a third temperature at which the temperature of the fixing unit can be raised while fixing the first toner image formed according to the image on the first recording material;
The third temperature may increase the temperature of the fixing unit while fixing the first toner image formed according to an image other than the character image and the halftone image on the first recording material. higher than the possible second temperature;
The image forming apparatus is characterized in that the first temperature information includes the first temperature, the second temperature, and the third temperature.

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