JP3225899B2 - Image forming method and image forming control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color recording head and a black recording head in which a plurality of printing elements are arranged in a sub-scanning direction in parallel in a main scanning direction. The present invention relates to an image forming method in a serial printer that forms an image by driving the black head while moving the same in the main scanning direction, and an image forming control device that performs such control.

[0002]

2. Description of the Related Art FIG. 2 is a schematic diagram showing an example of a general serial printer. In the figure, 1 is a carriage driving motor, 2 is a timing belt, 3 is a recording head, 4 is a carriage, 5 is an ink tank, 6 is a carriage guide, 7 is a cable, 8 is a recording paper, 9 is a paper feed motor,
Reference numeral 10 denotes a feed roll. In this example, an ink jet printer is shown as an example of a serial printer.

The carriage 4 has the recording head 3 mounted thereon,
The carriage guide 6 slides and reciprocates in the main scanning direction indicated by the arrow H in the drawing. The movement of the carriage 4 is performed by a timing belt 2 driven by a carriage drive motor 1. In this example, two recording heads 3 are arranged in the moving direction of the carriage 4.

A cable 7 is introduced into the recording head 3 to supply power to a heater in the recording head 3 and transmit a signal to a drive circuit. An ink tank 5 is attached to each recording head 3 to supply ink of each color. A plurality of nozzles are arranged in each recording head 3, and the supplied ink is ejected from the nozzles, and recording is performed on recording paper 8. The recording paper 8 is driven in a direction indicated by an arrow P in the drawing by a feed roll 10 which is driven to rotate by a paper feed motor 9 to perform sub-scanning.

When a color image is formed by the above-described ink jet printer, a full-color image is generally formed by using cyan, magenta, and yellow inks. However, when these color inks are used, there is a problem that black color developability is poor. Also,
As an image to be formed, in addition to a multicolor image such as a photographic image, there are many images of one color such as text, particularly one color of black. Therefore, the use frequency of black is high, and the ink tank needs to be frequently replaced. From such a background, black ink is used separately from the above-described three color inks.

In the case of forming an image with these four inks, as one example, a configuration in which a recording head is provided for each color and the four recording heads are arranged in the main scanning direction has been developed. However, mounting such a large number of recording heads has a problem that the entire apparatus becomes large and costs are high, so that it cannot be adopted in a small and low-cost image forming apparatus.

On the other hand, as described above, in the text portion, image formation using one black color is frequently performed, and the frequency is high. Therefore, high-speed black image formation is required. In order to respond to such a demand for high speed, the recording width of the head for recording black is made wider than the recording width of other colors, and when forming an image of only black, recording is performed using the entire black head. To achieve high-speed recording.

FIG. 2 shows a color head in which a color other than black is mounted on one head and a black head containing only black in order to realize such an apparatus with reduced size, reduced cost, and high-speed printing. As described above, a two-head type configuration arranged on the carriage in the main scanning direction has been developed. FIG. 3 is a schematic diagram illustrating an example of a two-head type recording head. In the figure, 11 is a black head, 1
2 is a color head. BK is black, C
Represents cyan, M represents magenta, and Y represents yellow. A number of printing elements are arranged in each recording head in the vertical direction (sub-scanning direction) in the figure. The printing element corresponds to, for example, a nozzle and an ink ejecting element in an inkjet method. In FIG. 3, the printing elements are linearly arranged. Alternatively, the printing elements may be arranged in a staggered manner.

In the black head 11, black printing is performed by using all the printing elements arranged or a part of the printing elements. In the color head 12, the arranged printing elements are divided into segments according to the number of colors used. Here, a case where three colors of cyan, magenta, and yellow are used is shown. Of course, other colors may be used. An interval is provided between the printing elements of different colors.

In such a recording head, as described above, the number of printing elements capable of printing black is greater than the number of printing elements capable of printing another color. When an image of only black is recorded using such a recording head, recording can be performed in units of the width of the black head at the maximum, so that high-speed printing is possible. A method of performing recording with such a wide recording width is called a black mode. Further, in a color image including a color other than black, printing can be performed only in units of the width of one color arranged in the color head at the maximum. Such a method of recording for each color width of the color head is called a color mode.

In the conventional image forming apparatus, once the color mode is set, recording is performed only in the unit of color image formation even in the area of only black. for that reason,
For documents that have both color areas and black-only areas,
Even if there is only a black area where high-speed printing is possible, high-speed printing is not performed, and there is a problem that the printing speed is relatively reduced.

In order to solve such a problem, for example,
As described in Japanese Patent Application Laid-Open No. H8-238805, it is checked whether a recording target contains a color other than black or only black, and the color mode and the black mode are changed depending on the printing target. is there. Accordingly, in a document in which an area including a color other than black (hereinafter, referred to as a color area) and an area including only black (hereinafter, referred to as a black area) are mixed, the black area is recorded by utilizing the recording width of the black head. This enabled high-speed printing as a whole.

FIG. 4 is a diagram illustrating an example of a problem in an example of a conventional image forming method. In the drawing, the hatched area indicates the area to be recorded in cyan. Characters are recorded in black. In the color mode, only a portion of the black head having a width corresponding to the recording width of one color of the color head is used. In the color mode, for example, FIG.
Consider the case of using the upper part in. In this case, the same area as yellow is recorded by the black head. The area of the black head used at this time is called a used segment. In this example, 100% printing is performed by one main scan, and the feed amount in the sub-scanning direction in the color mode is the printing width of one color of the color head.

A cyan area is detected in a line a in the figure, and recording in a color mode is started. From the head positions (1) to (2) in the drawing, printing is performed using the cyan segment of the color head. Also, black characters in the color area are recorded using the used segments of the black head.

In FIG. 4, line c is the end of the color area. In the above-described image forming method, the line c is a mode switching point. Then, the recording at the head position (2) ends the recording of cyan. After that, only black recording is performed, and recording in black mode becomes possible. However, the mode is not switched, and printing is performed in the color mode until black printing up to the switching point at the head position (5) is completed. Therefore, there is a problem that the recording speed is reduced.

FIG. 5 is an explanatory view of another example of the problem in one example of the conventional image forming method. In the figure, the hatched area indicates the area to be recorded in yellow. Characters are recorded in black.
In this example, it is assumed that, for example, the lower part in FIG. 3 of the black head is used in the color mode. In this case, recording by the black head is performed using the same area as cyan as the used segment. Also in this example, it is assumed that 100% printing is performed by one main scan, and the feed amount in the sub-scanning direction in the color mode is the print width of one color of the color head.

A yellow area is detected in a line a in the figure, and recording in a color mode is started. Because the yellow area contains black characters,
At the head position (1), recording by the black head starts. The recording operation in the color mode proceeds sequentially, and the end of the color area is detected on the line c. In the above-described image forming method, the line c is a mode switching point. Up to the head position (2), recording is performed by using segments of the black head and yellow segments of the color head, but at the next head position (3), the used segment of the black head exceeds the switching point. Do not record. The printing in the color mode is performed as it is, and the printing of yellow is completed at the head position (4). Thereafter, the mode is switched to the black mode, and recording using the entire black head is performed as shown in the head position (5).

However, from the head position (3) to the head position (4), the black head does not record anything. However, black recording is possible during this time, and the recording area in the black mode should be reduced accordingly. As described above, in the above-described image forming method, the recording mode does not shift to the black mode unless the recording up to the rear end of the color area is completed.

On the other hand, in Japanese Patent Application Laid-Open No. 8-244256, a black head having a wider head width than a color head is used similarly to the above-mentioned document, and recording is performed with a wide head width of the black head in a black area. The technology to be attempted is described. Also in this case, the transition from the color mode to the black mode is performed at the rear end of the color area. However, the configuration of the head is different, and a configuration in which color heads narrower than the black head are arranged in parallel for the number of colors is adopted. Therefore, the problem as shown in FIGS. 4 and 5 does not occur. However, since the number of heads increases, it cannot be used in a small-sized machine, and the cost is increased.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and in a small-sized image forming apparatus using a two-headed recording head as described above, a color area and a black area are provided. It is an object of the present invention to provide an image forming method capable of recording mixed images at a higher speed, and an image forming control apparatus using the image forming method.

[0021]

According to the present invention, when a trailing edge of a color area is detected during recording in a color mode, a segment used by a black head at the end of recording of the detected trailing edge of a color area is black. The point at which the image formation is completed is referred to as a switching point. During printing in the color mode, printing of the black area after the switching point is not performed, and image formation after the switching point is performed in the black mode after printing at the rear end of the color area. By controlling in this way,
For example, in the example of FIG. 4, the color mode can be ended at the head position (2) and the mode can be shifted to the black mode. Further, for example, in the example of FIG. 5, black is also recorded in the color mode up to the head position (4), and thereafter, the mode can be shifted to the black mode. Therefore, high-speed recording can be performed. Further, since the present invention uses a recording head having a two-head configuration as shown in FIG. 3, for example, it can be applied to a small and low-cost image forming apparatus.

The present invention is also applicable to an image forming method for forming an image in the same area by main scanning for the number of print divisions. Such an image forming method has an advantage that the image areas formed by the respective main scans overlap each other, so that the seams of the respective image areas do not become apparent. If it occurs in the middle of the process, this effect may not be exhibited. Therefore, the above-mentioned switching point is set as a provisional switching point, and if there is an area without black within a predetermined width after the provisional switching point, the area is updated as the switching point, thereby eliminating the problem at the time of mode switching. be able to.

[0023]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 21 is a host device, 22
Is a communication unit, 23 is a command analysis unit, 24 is a head position management unit, 25 is an image transfer unit, 26 is a head control unit, 27 is a head, 28 is an image memory, and 29 is a band buffer. The communication unit 22 receives a print command sent from, for example, the host device 21 or the like. The communication unit 22 may be directly connected to the host device 21 or may be connected via a network or the like. Alternatively, a configuration may be employed in which a print command is retrieved from the storage device by being connected to a storage device such as a disk.

The command analysis unit 23 analyzes the print command received by the communication unit 22, and sets and changes a set value and generates bitmap image data for recording according to the print command. The generated bitmap image data is stored in the image memory 28. Further, when some processing is set for the generated bitmap image data, the processing may be performed. Of course, when a bitmap image is sent as a print command, it is stored in the image memory 28 as it is or after performing a predetermined process.

The head position management unit 24 includes an image memory 28
At least the position in the sub-scanning direction to be recorded next is determined based on the image data and the recording mode stored in the head, the position of the head 27 in the sub-scanning direction is controlled according to the position, and the recording is performed at that position. The image transfer unit 25 instructs the image transfer unit 25 to transfer the image data of the recording area for each color.
In the following description, it is assumed that the above-described black mode and color mode are provided as recording modes. It is also assumed that the recording operation is performed while appropriately switching these two recording modes. The head position management unit 24 also controls the operation at the time of switching the recording mode.

The image transfer unit 25 includes a head position management unit 24
According to the position of the head 27 in the sub-scanning direction determined by
Image data corresponding to a band-shaped area (hereinafter, referred to as a band) recorded by each color segment in the head 27 is taken out from the image memory 28 and stored in the band buffer 29.

When the image transfer unit 25 completes the transfer of the image data to the band buffer 29, the head control unit 26 sequentially reads out the image data in the band buffer 29 and responds to the movement of the head 27 in the main scanning direction. , A driving pulse is applied to the head 27.

The head 27 is, for example, a two-head type recording head composed of the color head 12 and the black head 11 as shown in FIG. 3, and is read out from a driving pulse supplied from the head control unit 26 and from the band buffer 29. Dots are recorded on the recording medium according to the image data.

In the example shown in FIG. 1, the host device 2
Although an example in which a print command is sent from No. 1 has been described, the command analyzer 23 is unnecessary in a printer that accepts only bitmap image data. Further, the function up to the image transfer unit 25 may be realized on the host device 21 side, and the image data for recording whose position is managed by the head position management unit 24 may be transferred to the band buffer 29 and printed. . Further, although the image memory 28 and the band buffer 29 are shown as different configurations in FIG. 1, they may be secured as different areas in the same storage device.

Next, an example of the operation according to the embodiment of the present invention will be described. When a print command is sent from the host device 21, it is received by the communication unit 22 and passed to the command analysis unit 23. The command analyzing unit 23 analyzes the sent print command, sets and changes various set values, and generates bitmap image data for recording according to the print command. The generated image data and the image data sent in the bitmap format are stored in the image memory 2.
8 is written.

The head position management unit 24 includes an image memory 28
Pre-read the image in, according to the image to be formed,
At least the position of the head 27 in the sub-scanning direction is determined.
For example, when there is a blank area to some extent from the current tip position of the head 27, the blank area does not need to be printed, and may have a function of performing a white skip operation of moving the head 27. of course,
The position of the head 27 in the main scanning direction may also be determined, and control may be performed to skip when a blank area exists in the main scanning direction.

The head position management unit 24 performs control according to the recording mode. That is, printing control in the black mode is performed in an area where only black images are continuous, and printing control in the color mode is performed in an area where images including colors other than black are continuous. At this time, at least the position of the head 27 in the sub-scanning direction is determined according to each recording mode and its state, and the image transfer unit 25 is instructed on the area of the image data to be transferred to the band buffer 29. The processing in each mode will be described later.

In the head position management unit 24, the head 27
When at least the position in the sub-scanning direction is determined, the image transfer unit 25 extracts from the image memory 28 the image data of the band recorded when the main scanning is performed at the determined position of the head 27, and 29. For example, in the configuration of the head shown in FIG.
Even if 7 is at the same position, the recording areas are different for cyan (C), magenta (M), and yellow (Y).
Therefore, image data corresponding to the recording area of each color is taken out from the image memory 28. Since the recording area of the black head 11 is different between the black mode and the color mode, the image data of the recording area corresponding to the mode is taken out from the image memory 28 and stored in the band buffer 29.

After transferring the image data to the band buffer 29, the image transfer unit 25 instructs the head control unit 26 to execute a printing operation. The head control unit 26 reads out image data from the band buffer 29 and sends a driving pulse to the head 27 in accordance with the movement timing of the head 27 in the main scanning direction. The head 27 performs recording using image data and a driving pulse. For example, when the image data of a certain dot is “1”, the printing of that dot is performed at the timing when the drive pulse is given.

Next, the operation of the head position management unit 24 in each recording mode will be described. FIG. 6 is a flowchart illustrating an example of the operation of the head position management unit 24 in the black mode according to the embodiment of the present invention. In this example, it is assumed that 100% printing is performed in an area where printing is performed by one main scan. Here, it is assumed that the operation is performed in the black mode first. In black mode, S4
In step 1, image data of each color is pre-read by the recording width of the black head. In S42, it is determined from the pre-read image data of each color whether the image data to be recorded is color data containing a color other than black or black data of only black, and whether color data exists within the pre-read range is determined. Is determined. If there is no color data, in S43, printing in the black mode is continued using the pre-read black data. In the black mode, the entire width of the black head is used for recording, and the movement in the sub-scanning direction is performed for each recording width of the black head.

If color data exists within the pre-read range, the line immediately before that line is stored as a mode switching point in S44. In S45, the mode switching point is determined as a new position of the head 27, and the relative position of the head 27 in the sub-scanning direction is controlled. Then, in S46, recording is performed in the black mode up to the mode switching point. At this time, the relative movement in the sub-scanning direction performed in S45 is smaller than the recording width of the black head 11. For this reason, printing is not always performed using the entire recording width of the black head 11. Therefore, the image transfer unit 25 follows the instruction of the head position management unit 24 so that only the image data for the recording width at this time is recorded. The image data is transferred to the buffer 29 and recorded. After the image up to the mode switching point is formed in this way, the mode shifts to the color mode.

FIG. 7 is a flowchart showing an example of the operation of the head position management unit 24 in the color mode according to the embodiment of the present invention. Here, it is assumed that the operation is performed in the color mode. In the color mode, recording is performed using both the black head 11 and the color head 12. At this time, the black head is the color head 12
Only the number of dots having the same width as the monochrome segment width is used as the used segment. The position of the used segment is arbitrary, but it is preferable to control the position to be the same as the segment of any color of the color head 12.

In the color mode, in step S51, a black image having no color other than black is detected. First, image data of each color is read ahead by a single-color segment width. At the time of pre-reading, image data is read from the first dot of each color in consideration of the shift amount of the recording position for each color. Then, it is determined whether or not there is color data therein. If there is color data, it is determined that color data exists, and the process proceeds from S52 to S53.

In S53, a normal recording operation in the color mode is performed. In the normal operation in the color mode, the relative movement in the sub-scanning direction is performed by the segment width of a single color of the color head, and the color head and the black head are driven to perform main scanning to perform printing. When the color head is a three-color integrated head, the relative movement amount of the head 27 in the sub-scanning direction in the color mode is about 1/3 or less of that in the black mode. In the case of the configuration shown in FIG.
It is about 1/4. Conversely, in the black mode, printing can be performed at three times or more the speed in the color mode, for example, four times in the configuration shown in FIG.

If there is no color data in S52,
At this point, the mode is switched. Alternatively, image data of each color for the entire width of the black head is read in advance from several bands, and it is determined whether or not color data exists in the image data. Only when no color data exists, switching to the black mode is performed. In the latter case, if there is color data in the pre-read image data, the process proceeds to S53.

In S54, the rear end of the used segment of the black head at the position in the sub-scanning direction where the rear end (end end) of the color area is recorded is set as a mode switching point.
The mode switching point may be in the color area or in the black area depending on the position of the used segment in the black head and the image data. Then, in S55, the movement in the sub-scanning direction is performed so that the tip of the black head becomes the mode switching point, and the mode shifts to the black mode.

By such an operation, when the mode switching point is in the color area, it is possible to record in the black mode from the black image in the color area. When the mode switching point is in the black area, since the black image from the rear end of the color area to the mode switching point has already been formed in the color mode, there is no need to perform another printing operation.
Therefore, high-speed recording is possible.

Using the specific example, the above-described head position management unit 2
An example of the operation 4 will be described. In the following description, it is assumed that the color head has the same segment width for each of the three colors cyan, magenta, and yellow.
From the rear end (lower end) of the head, cyan, magenta, and yellow are set in order. The black head has a width four times as large as the single color segment width of the color head. The head position indicates the lower end of the print area of the head, and the upper end of the recording medium is assumed to be the current position as an initial state. The relative movement in the sub-scanning direction is described as moving the recording medium. In FIGS. 8 to 10 shown below, portions used for recording in each head are hatched.

FIG. 8 is an explanatory diagram of a specific example of an operation including switching from the black mode to the color mode of the head position management unit according to the embodiment of the present invention. In the example shown in FIG. 8, the line “ABCDE...” And “1234”
.. And the line of “abcde...” Are repeatedly recorded. These are recorded in black. The hatched portions of the fifth and subsequent rows are recorded in cyan.

In the initial state, the head position is at the upper end of the recording medium. Since there is a blank at the upper end of the image data, the recording medium is sent to this portion, and the head position is adjusted to the upper end of “ABCDE... In this state, the image data for the recording width of the black head is pre-read. In the example of FIG.
The image data from line a to immediately before line b is pre-read. In this, a black image exists, but no color data other than black exists. Therefore, the recording operation is performed in the black mode. Head position at line b
To control the feeding of the recording medium, and make the image transfer unit 25 transfer the image data from line a to immediately before line b. By performing main scanning at the position (1) in the drawing, printing is performed in an area from line a to immediately before line b according to the entire printing width of the black head.

After printing at the position (1) in the drawing, the black mode is maintained. Therefore, the image data of the entire recording width of the black head is pre-read. In this case, color data exists on line c. Therefore, the line immediately before the line c is held as a mode switching point.

Then, the feeding of the recording medium is controlled so that the head position becomes the mode switching point, and the image data from line b to immediately before line c is transferred to the image transfer unit 25. Then, by performing the main scanning at the position (2) in the drawing, the area from the line b to the line immediately before the line c is printed using a part of the black head. Thereafter, the mode is switched to the color mode.

The data from line c onward is recorded in the color mode. In the color mode, first, image data of a single color segment width in the color head is pre-read. Here, image data from line c to immediately before line d is pre-read. Since cyan color data exists therein, the recording medium is moved in the sub-scanning direction by a single-color segment width, and main scanning is performed to form a cyan image from line c to immediately before line d. . At this time, if the used segment of the black head is set at a position overlapping the cyan segment, a black image is also formed. Hereinafter, image formation in the color mode is performed.

FIG. 9 is an explanatory diagram of a first specific example of an operation including switching from the color mode to the black mode of the head position management unit according to the embodiment of the present invention. In the example shown in FIG. 9, "ABCDE...
. "," 12345 ... "," abcde ... "are repeatedly recorded in black. The hatched portions are recorded in cyan. In the first specific example, in the color mode, the black head records the upper 1/4 as the used segment. That is, recording is performed at the same position as yellow.

In the example shown in FIG. 9, line a is the head of the image. The head position is set immediately before line a, and image data of each color having a single-color segment width is read in advance. That is, cyan image data from line a to immediately before line b is pre-read. Color data exists in this. Therefore, recording is performed in the color mode. The head position is set to the line immediately before the line b to control the feeding of the recording medium. Also, the line a
, And the image data of cyan from immediately before line b. By performing main scanning at the position (1) in the figure,
Line a using the cyan segment of the color head
The recording of the area from to the position immediately before the line b is performed. Since black performs recording at the position of the yellow segment, the black head does not perform recording at this position.

When such a recording operation in the color mode is repeated, recording of a black image by the black head is started after the position (2) in FIG. At the position (2), a black image from the line a to immediately before the line b is recorded according to the used segment of the black head. Also at this position, cyan recording from line d to immediately before line e is performed.

Further, the recording operation in the color mode is repeated, and the main scanning is performed at the position (3) in the figure, thereby completing the cyan area up to the line f. When pre-reading each color of the next single color segment width, no color data exists. That is, the color mode ends by the main scanning at the position (3) in the drawing. At this time, the line immediately before the line c which is the rear end of the used segment in the black head is held as a mode switching point. Then, the feeding of the recording medium is controlled so that the leading end of the black head is located at the line c, and the mode shifts to the black mode. Then, the data after the line c is recorded in the black mode.

Conventionally, up to line e, printing was performed in color mode only with black, but as described above, in the present invention, black data after line c can be printed in black mode. Therefore, an image can be formed at a higher speed than before.

FIG. 10 is an explanatory diagram of a second specific example of the operation including switching from the color mode to the black mode of the head position management unit according to the embodiment of the present invention.
In the example shown in FIG. 10, "ABCDE...
. "," 12345 ... "," abcde ... "are repeatedly recorded in black. The hatched portion is recorded in yellow in this example.
In the second specific example, in the color mode, the black head records 1/4 of the lower end as a used segment. That is, recording is performed at the same position as cyan.

In the example shown in FIG. 10, line a is the head of the image. The head position is set immediately before line a, and image data of each color having a single-color segment width is read in advance. There is no color data in this. Therefore, the data of each color is read ahead by the entire width of black. Then, yellow image data from line a to immediately before line b is present in the yellow pre-read data. Therefore, recording is performed in the color mode. In addition, black image data is included in the pre-read data of the single-color segment width. The head position is set to the line immediately before the line b to control the feeding of the recording medium. Further, it causes the image transfer unit 25 to transfer black image data from line a to immediately before line b. By performing the main scanning at the position (1) in the drawing, the recording from the line a to immediately before the line b is performed using the used segment at the same position as the cyan of the black head. At this point, since the yellow segment has not reached the position to be recorded, the yellow recording is not performed.

When the black recording operation in such a color mode is repeated, the recording of the yellow image by the yellow segment of the color head is started after the position (2) in the drawing. At the position (2), the yellow image from the line a to immediately before the line b is recorded by the yellow segment. Also at this position, line e
The black recording is performed by the use segment of the black head from to the line just before the line f.

Further, the printing operation in the color mode is repeated, and the main scanning is performed at the position (3) in the figure, thereby completing the printing of the color area including the line c which is the end of yellow with yellow. At the time of this main scanning, the printing operation is performed by the segments used by the black head to form a black image from line f to immediately before line g. At this point, the color mode ends.

At this point, the formation of the image in the black area from immediately after the line c to immediately before the line g has already been completed. By this time, the line immediately before the line g at which the black head has finished forming the black image is held as a mode switching point. Then, the feeding control of the recording medium is performed so that the leading end of the black head is positioned at the line g, and the mode shifts to the black mode. And line g
The following is recorded in the black mode.

Conventionally, the black image was not recorded until after the color image up to the line c was recorded in the color mode. Therefore, until the yellow recording was performed at the position (3) in FIG. No images were recorded. However, in the present invention, since the black data after the line c is also recorded in the color mode as described above, in this example, the time for recording immediately after the line c to immediately before the line g can be omitted. An image can be formed at a higher speed than before.

In the operation example of the head position management unit 24 described above, a case where a 100% image is formed by one main scan has been described. As one of the recording methods, a method of forming an image by performing a plurality of main scans on the same area is also used. Hereinafter, a case where this recording method is used will be described. The number of main scans performed to form a 100% image is referred to as a print division number. When the print division number is 2, only 50% of the image is formed by one main scan. A 100% image is formed by two main scans. In addition, between the first main scan and the second main scan, the feed in the sub-scanning direction is performed at a half width of the entire recording width of the segment of the color head or the black head.

FIG. 11 is an explanatory diagram of an example of an image formed by two main scans. In FIG. 11, only one color of color or black is shown, and only a few dots are shown. First, in the main scanning shown in FIG. 11A, print data is created by thinning out image data by 50%.
Make a record. Here, it is assumed that the dot indicated by a circle is recorded. After the recording in FIG. 11A, a relative movement in the sub-scanning direction of half the recording width of the color is performed so as to be at the position in FIG. 11B. In the main scanning shown in FIG. 11B, print data of a pattern complementing the dots recorded in FIG. 11A is created and recorded. Here, it is assumed that dots indicated by X are recorded. As a result, as shown in the middle area shown in FIG.
00% of the image is formed.

By performing such a plurality of main scans, 100
%, Depending on the printing method (hereinafter, referred to as the divided printing method) for forming a% image, a mismatch between seams of the main scanning areas caused by a movement error in the sub-scanning direction, and a dot position caused by a variation in characteristics of each printing element. The inconsistency is less noticeable. In addition, in the image forming apparatus of the ink jet system, there is also an effect that bleeding is reduced by reducing the number of adjacent dots recorded at the same time, and an image can be improved.

This division recording method can be applied to both the black mode and the color mode. For example, in the black mode, the recording operation by the main scanning may be performed while performing the relative movement in the sub-scanning direction for each length obtained by dividing the entire recording width of the black head by the number of print divisions. Similarly, in the case of the color mode, the recording operation by the main scanning may be performed while performing the relative movement in the sub-scanning direction for each length obtained by dividing the width of the monochrome segment by the number of print divisions.

However, the following problem occurs when the mode is switched. FIG. 12 is an explanatory diagram of a problem at the time of switching the mode from the black mode to the color mode in the case of using the divided recording method. Here, the number of print divisions is two. In the figure, the area A shown on the left is a black area, and the area B is a color area. Now, it is assumed that the recording head exists at the sub-scanning position shown by (1) in the drawing. In the next main scanning, the tip of the head is moved to the line b, and the main scanning is performed in the state (2) in FIG.
The first main scan of the region from to is performed. In this state, only 50% of the image is formed in the region from line a to line b, and another main scan is required. If printing is continued in the black mode, the printing head is relatively moved to the position in the sub-scanning direction shown by (3) in the figure, and the second main scanning is performed for the area from line a to line b. .

However, at the position indicated by (3) in the figure, the color at the bottom of the color head in the figure exceeds the head of the area B. For this reason, even if the color mode is shifted from this position to the color mode and color printing is to be performed, the lowermost color in the drawing of the color head in the color area (area C) from line b to line c can be printed. Can not.

The same applies to the transition from the color mode to the black mode. FIG. 13 is an explanatory diagram of a problem at the time of switching the mode from the color mode to the black mode in the case of using the divided recording method. Here, the number of print divisions is two. Further, this example shows an example in which the mode switching point exists in the color area. In the figure, the lower area A shown on the left side is a black area, and the upper area B is a color area. Assuming that the line a is a mode switching point, in a normal black mode printing operation, (1) in FIG.
After the main scanning is performed by aligning the tip of the black head with the mode switching point as shown in (1), the relative movement in the sub-scanning direction is performed by half of the total recording width of the black head, and the main scanning is performed at the position (2) in the figure. Will be performed. However, if such a printing operation is performed, only one main scan is performed in an area (area C) that is half the total printing width of the black head from the mode switching point, and a desired density is obtained. Can not do.

As one method for solving such a problem, for example, when switching from the black mode to the color mode, it is possible to complete the black image up to the mode switching point and then shift to the color mode. Good. FIG. 14 is an explanatory diagram of an example of the operation at the time of switching the mode from the black mode to the color mode in the case of using the divided recording method. As in FIG. 12, the area A shown on the left side in the figure is a black area, and the area B
Is a color area. The number of print divisions is set to two. Now, the leading end of the head is moved from the position (1) in the figure to the line b, and the main scanning is performed in the state (2) in the figure.
The first main scan of the region from to is performed. In this state, only 50% of the image is formed in the region from line a to line b, and another main scan is required. Therefore, the recording by the black head is performed only in the area from the line a to the line b without changing the position of the head in the sub-scanning direction. As a result, a 100% image is formed in the region from line a to line b. Then, the mode shifts to the color mode. By performing such control, it is possible to prevent the occurrence of an unrecordable area such as the area C in FIG.

The same is true when shifting from the color mode to the black mode. FIG. 15 is an explanatory diagram of an example of an operation at the time of mode switching from the color mode to the black mode in the case of using the divided recording method. In the figure, the lower area A shown on the left side is a black area, and the upper area B
Is an image area formed of cyan and black. It is assumed that the used segment of the black head in the color mode is the same position as the yellow segment located at the tip of the color mode. The number of print divisions is two.

Now, at the position (1) in the figure, the second main scanning of cyan from line e to line f and the first main scanning from line f to line g which is the end of the color area are performed. Second black main scan from line a to line b by the black head and line b
Is performed for the first time from line to line c. At this point, it can be seen that the next main scan completes the color area. Also, it can be seen that the black image completed by the next main scan is up to the line c. Therefore, the line c is held as a mode switching point.

The main scanning is performed at the position (2) in the figure by making a relative movement in the sub-scanning direction by a distance equal to one-sixth of the segment length, ie, half the segment length.
At this time, since cyan has data only from line f to line g, the second recording of this area is performed. In the color mode, the black head does not perform recording after the mode switching point. That is, at the position (2) in the drawing, only the second recording from the line b to the line c is performed.

Then, the tip of the head is moved to the line c, which is a mode switching point, and the mode shifts to the black mode to perform main scanning at the position (3) in the figure. In the initial stage of the black mode, the main scanning is performed by the number of print divisions while increasing the recording width of the black head at the same sub-scanning position.
In the position (3) in the figure, the front half of the black mode is １ ／.
Is used to perform the first recording from line c to line e. Next, without moving in the sub-scanning direction, printing is performed at the same sub-scanning position as in (3) in the drawing, using the entire printing width in the black mode as shown in (4) in the drawing. Thus, the second recording from line c to line e is performed, and a 100% image is formed. The first recording from line e to line i is also performed. Thereafter, recording may be performed in the normal black mode.

The same applies to the case where the mode switching point exists in the black area. When the rear end of the color area is detected, the rear end of the black image completed before the image of the color area is completed is set as the mode switching point. When the mode is switched to the black mode by aligning the tip of the head with the mode switching point, the main scanning may be performed the number of times of the print division while increasing the recording width of the black head at the same sub-scanning position.

By performing such recording control, it is possible to perform the above-described mode switching control even when the divided recording method is used, and by performing recording in a mode corresponding to each area, high-speed recording is performed. To form an image.

When the recording control using the above-described divided recording method is performed, the main scanning is repeated while moving the head little by little as described above, and the image forming area by each main scanning is overlapped. White streaks and density unevenness that occur due to the feed accuracy in the sub-scanning direction are made inconspicuous at seams of image forming areas by scanning.
Therefore, a high-quality image can be printed in the color mode or the black mode. However, FIG. 14 and FIG.
When the recording control as shown in (1) is performed, the main scanning is not performed across the area for recording in the color mode and the area for recording in the black mode at the mode switching point. Therefore, there is a possibility that white streaks and density unevenness at joints become remarkable at the mode switching point.

In order to avoid such a problem,
Adjust the mode switching point. FIG. 16 is an explanatory diagram of updating a mode switching point. For example, when shifting from the black mode to the color mode, as shown in FIG. 16A, when there is a continuous black area before the color area, and when there is a blank area before the black area, May be set to the blank area as a mode switching point.

When shifting from the color mode to the black mode, as shown in FIG. 16B or FIG. 16C, the mode switching point (shown by a broken line) held as described above is held. Is set as the provisional mode switching point, and if the provisional switching point is over the black image, it is checked whether or not there is an area without the black image in a predetermined range after the black image. And
If there is an area without a black image, the area is updated as a mode switching point. The update of the mode switching point may be updated to a region where there is no black image in a predetermined range before the black image.

As described above, by updating the mode switching point to a portion where a black image does not exist as much as possible, it is possible to reduce the occurrence of white stripes and density unevenness in the black image when the mode is shifted to the black mode. Can,
A good image can be formed.

As described above, the head position management unit 24 in the case where the division recording method is used and the mode switching point is further adjusted.
An example of the operation will be described using a specific example. In FIGS. 17 to 20 shown below, FIGS.
0 has the same head configuration. In this example, it is assumed that the number of print divisions is 2, and the same area is recorded so that a 100% image is formed by two main scans.

FIG. 17 is an explanatory diagram of a specific example of an operation including switching from the black mode to the color mode in the case of using the divided recording method of the head position management unit according to the embodiment of the present invention. Characters in the figure are recorded in black, and hatched portions are recorded in cyan. This cyan part is the character "12345
・ ・ ”.

The head position is "ABCDE..." On the first line.
The image data of each color, which is aligned with the upper end of "." Here, since the number of print divisions is two, it is。 of the recording width. In the example of FIG.
The image data up to just before is pre-read. In this, a black image exists, but no color data other than black exists. Therefore, the mode is set to the black mode. The head position is set immediately before line a to perform feed control in the sub-scanning direction, and the image generation unit 25 transfers image data from line a to immediately before line b.
By performing main scanning at the position (1) in the figure, the first half of the area from line a to immediately before line b is recorded by the lower half of the black head.

Further, the image data of each color of 1/2 of the printing width of the black head is read in advance. Also in this case, since there is no color data in the pre-read range, the head position is set immediately before the line c to control the feed in the sub-scanning direction. Transfer the image data. By performing the main scanning at the position (2) in the drawing, the second recording of the area from the line a to immediately before the line b and the first recording from the line b to immediately before the line c are performed using the entire black head. Is recorded. At this time, as shown in FIG. 11, when transferring the image data, the image data is thinned out by a filter or the like so that a dot different from the dot formed in the previous main scanning is formed.

Further, the printing width of the black head is １ ／.
The image data of each color is pre-read. In this case, color data exists on line e. Therefore, the line immediately before the line e is temporarily held as the provisional mode switching point. Then, a blank line is searched before the line e. In this example, the line immediately before the line d is a blank line. Therefore, the line immediately before the searched line d is updated as the mode switching point.

The image is completed in the black mode for the area up to the mode switching point (immediately before the line d). That is, since the number of print divisions is two, the rear end of the head is aligned with the line d, and two main scans are performed at the same head position. At this time, the recording is performed while reducing the recording width of the black head to be used. First, recording from line b to immediately before line d is performed at the position (3) in the drawing. As a result, the second main scan of the area from line b to immediately before line c is performed, and the area from line c to the line immediately before line d is 1
A second main scan is performed. Further, the main scanning is performed again without changing the head position, as shown in FIG. At this time, the line c to the line d
Is recorded by transferring only the image data up to immediately before. Thereby, 2 from the line c to immediately before the line d is obtained.
The second main scan is performed.

After forming the image up to the mode switching point (immediately before the line d) in this way, the mode is switched to the color mode. Thereafter, a recording operation in the color mode is performed. The recording operation in the color mode is the same as in the above-described example, and the description is omitted. The range of prefetching is
1 / multiple of the print division of the single color segment width of the color head
Is the width of Although only black data exists from line d to line e, this area is also recorded in the color mode. In (5) in the figure, since there is no cyan data from line d to immediately before line e, a skip operation is performed. At (7) in the figure, black recording starts.

FIG. 18 is an explanatory diagram of a first specific example of the operation including switching from the color mode to the black mode in the case of using the division recording method of the head position management unit according to the embodiment of the present invention. . Also in this example, the character portion is recorded in black, and the hatched portion is recorded in cyan. Also, as in the case of FIG. 9, in the first specific example, in the color mode, the black head records the upper 1/4 as the used segment. That is,
It is assumed that recording is performed at the same position as yellow.

In the example shown in FIG. 18, line a is the head of the image. The head position is set immediately before the line a, and the image data of each color in the area of 印字 of the printing width of a single color is read in advance. That is, the image data from line a to immediately before line b is pre-read. Color data exists in this. Therefore, recording is performed in the color mode. The head position is set to the line immediately before the line b, and the feed control in the sub-scanning direction is performed. Also, the image generation unit 2
5 causes the cyan image data from line a to immediately before line b to be transferred. By performing main scanning at the position (1) in the figure, the lower end 1/1 of the cyan print width of the color head is obtained.
2, the first recording of the area from line a to immediately before line b is performed.

Further, 1/1 of the printing width of the single color of the color head.
The image data of each color is pre-read. Also in this case, since the color data exists within the pre-read range, printing in the color mode is performed. That is, the head position is set to the line immediately before the line c, and the feed control in the sub-scanning direction is performed. In addition, the image transfer unit 25 transfers the cyan image data from line a to immediately before line c. By performing main scanning at the position (2) in the figure, the second recording of cyan in the area from line a to immediately before line b is performed using the entire cyan segment width of the color head.
The first recording of cyan from line b to immediately before line c is performed.

Similarly, recording in the color mode proceeds. The head position is line g, ie, (3) in the figure.
The recording of black data starts at the position of. Along with recording with the cyan segment of the color head, the line a
The first recording of the black image from to is performed immediately before line b. In the main scanning at the subsequent head position of the line h, that is, the position of (4) in the figure, the recording is performed by the cyan segment of the color head, and from the line a to immediately before the line b using the full width of the used segment of the black head. The second recording of the black image and the first recording of the black image from line b to immediately before line c are performed.

After the main scanning at the position (4) in the figure, the image data of each color having a half of the single-color segment width is read in advance. In this case, there is no color data on line j. At this point, it can be seen that the color area is completed by the next main scan including the line j (main scan of (5) in the figure) and the next main scan (main scan of (6) in the figure). At this time, it can be seen that the range of the image completed by the next main scan and the next main scan by the used segment of the black head is immediately before the line d. So line d
Is held as a provisional mode switching point.

However, black data exists on the line d. Therefore, a line in which black data does not exist after the line d is searched for in a predetermined range, for example, a half range of a single color segment of the color head. In this case, there is no black data in line e. Therefore, the line e is updated as a new mode switching point.

The head position is set to the line immediately before the line k, and the feed control in the sub-scanning direction is performed. Further, the image transfer unit 25 transfers cyan image data from the line g to the position immediately before the line k (substantially, the line j).
The black image data from line b to immediately before line d is transferred. By performing the main scanning at the position (5) in the figure, the second recording of the area from the line g to the line immediately before the line h for cyan and the line h to the line j
The first recording of cyan up to is performed. For black, the second recording in the region from line b to immediately before line c and the first recording in the region from line c to immediately before line d are performed.

Next, in order to complete the image of the recording area in the color mode, the head position is set to the line immediately before the line l, and the feed control in the sub-scanning direction is performed. Further, it causes the image transfer unit 25 to transfer cyan image data from line h to immediately before line k (substantially line j), and transfer black image data from line c to immediately before line e. At this time, the black data after the line e, which is the mode switching point, is not transferred. By performing main scanning at the position (6) in the figure, the second printing of cyan from line h to line j is performed for cyan. For black, the second recording of the area from line c to immediately before line d and line d
The first recording of the area from to to the line e is performed. By the recording operation so far, the cyan image is completed.

If the mode switching point is not updated, the mode shifts to the black mode at this point. However, there is a black area in which recording has been performed only once because of the updated mode switching point. Therefore, the recording operation in the color mode is continued. Similarly, the head position is set to the line immediately before the line m, the feed control in the sub-scanning direction is performed, and the main scanning is performed at the position (7) in FIG.
For black, the second recording of the area from line d to immediately before line e is performed. Thus, a black image up to the mode switching point is also completed.

In this manner, the recording operation in the color mode is completed, the sub-scanning control is performed so that the tip of the black head is located at the updated mode switching point (line e), and the operation in the black mode is started. In this example, a mode switching point is set in an area where no black data exists. Therefore, no black data exists in a certain area including the mode switching point. An area where no black data exists can be skipped. In this example, since there is no black data in the region from line e to immediately before line f, the process skips to line f. That is, the feed control in the sub-scanning direction is performed so that the head of the black head comes to the line f.

In the main scanning for the first print division number in the black mode, black data is recorded while the recording area of the black head is gradually enlarged without changing the head position. Here, since the number of print divisions is two, two main scans are performed at the same head position. At the position (8) in the drawing, the image transfer unit 25 is caused to transfer the image data from the line f to a position immediately before the line i which is の of the full recording width of the black head and to perform main scanning. Thus, the first recording of black in the region from line f to immediately before line i is performed using only the upper half of the black head.

Then, without moving the head position, the image transfer unit 25 is caused to transfer the image data from line f to immediately before line n. By performing the main scanning at the position (9) in the drawing, the second recording of black in the region from line f to immediately before line i and the recording from line i to immediately before line n are performed using the entire black head. The first black recording is performed. Thereafter, the printing operation in the normal black mode, that is, the pre-reading of an area of の of the full recording width of the black head, the feed control in the sub-scanning direction of the same width, and the recording with the full recording width of the black head are performed. It will go.

As described above, even when the divided recording method is used, the recording can be performed by shifting to the black mode before the recording of all the color areas is completed.
High-speed recording can be performed as a whole. Further, by updating the mode switching point to a portion having no black data, it is possible to reduce white stripes, density unevenness, and the like, which are likely to occur at the time of mode switching. for that reason,
High-speed recording can be performed while utilizing the effect of improving the image quality by the division recording method.

FIG. 19 is an explanatory diagram of a second specific example of the operation including the switching from the color mode to the black mode in the case where the division recording method of the head position management unit is used according to the embodiment of the present invention. . In the second specific example, as in the case of FIG. 10, in the color mode, the black head records the lower quarter of the lower end as a used segment. That is, recording is performed at the same position as cyan. Also in this example, the character portion is recorded in black, and the hatched portion is recorded in yellow. Note that the operation is almost the same as that of FIG.

In the example shown in FIG. 19, the line a is the head of the image, and there are yellow and black data.
The head position is set immediately before the line a, and the main scanning is performed at the position (1) in the drawing, so that the area from the line a to the line immediately before the line b is obtained using the lower half of the used segment of the black head. Is recorded for the first time. Next, the head position is set to the line immediately before the line c, and the main scanning is performed at the position (2) in the figure. The second recording of black in the area and the first recording of black from line b to immediately before line c are performed.

Next, the head position is set to line e, and main scanning is performed at the position (3) in the figure. At this time, the line d which is the rear end of the color area
However, in the present invention, recording is performed using the entire used segment width of the black head as it is. As a result, the second recording of black in the region from line b to immediately before line c and the first recording of black from line c to immediately before line e are performed.

Similarly, recording in the color mode proceeds. Recording of black data by the black head is continued as it is. When the head position is at the line g, that is, at the position (4) in the drawing, the recording of yellow data starts. Along with the recording using the segments used by the black head, the first recording of the yellow image from line a to immediately before line b is performed using の of the yellow segment of the color head. In the main scanning at the subsequent head position at the line h, that is, at the position (5) in the figure, the recording from the used segment of the black head and the entire width of the yellow segment of the color head are used to print the line a to the line immediately before the line b. The second recording of the yellow image and the first recording of the yellow image from line b to immediately before line c are performed.

After the main scanning at the position (5) in the figure, if the image data of each color having a half of the single-color segment width is read in advance, no color data is present on the line d. At this point, it can be seen that the color area is completed by the next main scan including the line d (main scan of (6) in the figure) and the next main scan (main scan of (7) in the figure). At this time, it can be seen that the range of the image completed by the next main scan and the next main scan by the used segment of the black head is immediately before the line i. Therefore, the line i is held as a provisional mode switching point.

However, black data exists on line i. Therefore, a line in which black data does not exist after the line i is searched for in a predetermined range, for example, a half range of a single color segment of the color head. In this case, there is no black data on line j. Therefore, the line j is updated as a new mode switching point.

The head position is set to the line immediately before the line i, and the main scanning is performed at the position (6) in the figure. As a result, for black, the second recording in the region from line g to immediately before line h and the first recording from line h to line i are performed. For yellow, the second recording in the region from line b to immediately before line c and the first recording in the region from line c to line d are performed.

Next, in order to complete the image of the recording area in the color mode, the head position is set to the line immediately before the line k, and the main scanning is performed at the position (7) in the figure. Thus, for black, the second recording from line h to line i is performed, and the first recording from line i to just before line j is performed. At this time, black data after the line j which is the mode switching point is not recorded. Further, for yellow, the second recording of the area from line c to line d is performed, and the yellow image is completed.

If the mode switching point is not updated, the mode shifts to the black mode at this point. However, the black area (line i to line j immediately before j). Therefore, the recording operation in the color mode is continued. Similarly, set the head position to line m
The main scanning is performed at the position (8) in the figure, and the second recording of the area from line i to line j is performed for black. Thus, a black image up to the mode switching point is also completed.

Thus, the recording operation in the color mode is completed, the sub-scanning control is performed so that the tip of the black head is located at the updated mode switching point (line j), and the operation in the black mode is started. As in the example of FIG. 18, since black data does not exist in a certain area including the mode switching point, the process skips to the line 1 where the black data exists.

In the main scanning for the first print division number in the black mode, black data is recorded while the recording area of the black head is gradually enlarged without changing the head position. The head position is set to line 1, and in (8) in the figure, printing is performed using only half of the total printing width of the black head. Thereby, the first recording of black in the region from line 1 to immediately before line n is performed.

Then, without moving the head position, (9) in FIG.
At line l using the entire recording width of the black head.
The second recording of black in the area immediately before line n to the line n and the recording of black one in the area immediately before line n to line o
A second recording is performed. Thereafter, the printing operation in the normal black mode, that is, the pre-reading of an area of の of the full recording width of the black head, the feed control in the sub-scanning direction of the same width, and the recording with the full recording width of the black head are performed. It will go.

As described above, even when the divided recording method is used, the black area is continuously recorded while the color area is being recorded, so that high-speed recording can be performed as a whole. Further, by updating the mode switching point to a portion having no black data, it is possible to reduce white stripes, density unevenness, and the like, which are likely to occur at the time of mode switching. Therefore, high-speed recording can be performed while utilizing the effect of improving the image quality by the divided recording method.

In the above-described example of the division recording method, the number of print divisions is set to 2. However, even when the number of divisions is 3 or more, recording can be performed in the same manner. When switching modes,
At the end of the black mode or at the beginning of the black mode, main scanning may be repeated at the same position in the sub-scanning direction while reducing or increasing the recording width by the number of print divisions.

Note that the above-described image forming method and image forming control device may be realized in an image forming device main body,
In some cases, it is realized by being incorporated in a host device. In any case, for example, it can be realized as a program executed by the CPU. In such a case, the program and data used by the program can be stored in various storage media and read.

[0113]

As is apparent from the above description, according to the present invention, in a small-sized image forming apparatus using a recording head having a two-head structure, an image in which a color area and a black area are mixed can be further improved. High-speed recording is possible. Further, the present invention can be applied to the division recording method, and has an effect that high-speed recording can be performed while maintaining good image quality by the division recording method.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a general serial printer.

FIG. 3 is a schematic diagram illustrating an example of a two-head type recording head.

FIG. 4 is an explanatory diagram of an example of a problem in an example of a conventional image forming method.

FIG. 5 is an explanatory diagram of another example of a problem in an example of a conventional image forming method.

FIG. 6 is a flowchart illustrating an example of an operation in a black mode of a head position management unit according to the embodiment of the present invention.

FIG. 7 is a flowchart illustrating an example of an operation of the head position management unit in the color mode according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram of a specific example of an operation including switching from the black mode to the color mode of the head position management unit according to the embodiment of the present invention.

FIG. 9 is an explanatory diagram of a first specific example of an operation including switching from the color mode to the black mode of the head position management unit according to the embodiment of the present invention.

FIG. 10 is an explanatory diagram of a second specific example of an operation including switching from the color mode to the black mode of the head position management unit according to the embodiment of the present invention.

FIG. 11 is an explanatory diagram of an example of an image formed by two main scans.

FIG. 12 is an explanatory diagram of a problem at the time of mode switching from a black mode to a color mode in a case where a division recording method is used.

FIG. 13 is an explanatory diagram of a problem at the time of mode switching from a color mode to a black mode in a case where a division recording method is used.

FIG. 14 is an explanatory diagram of an example of an operation at the time of mode switching from a black mode to a color mode in a case where a division recording method is used.

FIG. 15 is an explanatory diagram of an example of an operation at the time of mode switching from a color mode to a black mode in a case where a division recording method is used.

FIG. 16 is an explanatory diagram of updating a mode switching point.

FIG. 17 is an explanatory diagram of a specific example of an operation including switching from a black mode to a color mode in a case where a divided recording method of a head position management unit is used according to an embodiment of the present invention.

FIG. 18 is an explanatory diagram of a first specific example of an operation including switching from a color mode to a black mode in a case where a divided recording method of a head position management unit is used according to an embodiment of the present invention.

FIG. 19 is an explanatory diagram of a second specific example of the operation including switching from the color mode to the black mode in the case where the division recording method of the head position management unit according to the embodiment of the present invention is used.

[Explanation of symbols]

1 ... carriage drive motor, 2 ... timing belt, 3
... Recording head, 4 ... Carriage, 5 ... Ink tank, 6
... Carriage guide, 7 ... Cable, 8 ... Recording paper, 9
... paper feed motor, 10 ... feed roll, 11 ... black head, 12 ... color head, 21 ... host device, 2
2 Communication unit 23 Command analysis unit 24 Head position management unit 25 Image transfer unit 26 Head control unit 27 Head 28 Image memory 29 Band buffer

Claims (6)

(57) [Claims] 1. A color head and a black head are arranged on a carriage in a main scanning direction, and the color head and the black head have a plurality of printing elements arranged in a sub scanning direction. Are divided into the same number of printing element segments for each different color, and the height of the printing element row of the black head is higher than the height of the printing element row of any color segment of the color head, and is read from the image memory. An image forming method for forming an image by driving while moving the color head and the black head in the main scanning direction based on the obtained image data,
When forming an image of a color area including a color other than black, recording is performed using the same number of printing elements as one segment of the color head of the black head as the used segments while using the segments of the respective colors of the color head. Form an image in color mode
When forming an image in a black area that does not include a color other than black, an image is formed in a black mode in which printing is performed using a larger number of printing elements than the segments of the black head, and printing is performed in a color mode. When the rear end of the color area is detected, the point where the used segment of the black head at the end of recording of the detected color area completes black image formation is held as a switching point, and An image forming method comprising: performing image formation after a switching point in a black mode after recording at a rear end. 2. The segment and the used segment in the color mode and the used printing elements of the black head in the black mode are divided into groups of the number of print divisions, and the same area is formed by main scanning of the number of print divisions. An image forming method for forming, during recording in the color mode, the black area after the switching point is not recorded,
In the initial stage of performing image formation after the switching point, the black head is repeated in the same sub-scanning direction at the same position in the sub-scanning direction, while repeating the main scanning by the same number of times as the print division number while increasing the number of printing elements used for recording. The image forming method according to claim 1. 3. When the trailing edge of a color area is detected during recording in the color mode, the point where the used segment of the black head completes image formation at the end of recording of the detected trailing edge of the color area is determined. Keep as a provisional switch point,
3. The image forming method according to claim 2, wherein when there is an area without black within a predetermined width after the provisional switching point, the area is updated as a switching point. 4. A color head and a black head are arranged in a main scanning direction on a carriage, and the color head and the black head have a plurality of printing elements arranged in a sub scanning direction. Is divided into the same number of segments for each different color, the height of the printing element row of the black head is higher than the height of the segment of any color of the color head, and the color head and the black head are based on image data. Position control for controlling at least the position and recording width of a head for forming an image in accordance with a mode in an image forming control device which controls the formation of an image by driving while moving in the main scanning direction. Means for transferring an image to a head according to a head position and a recording width determined by the head position management means. And a head position management unit that uses a segment of each color of the color head in a color mode for forming an image of a color region including a color other than black, and the color head of the black head. In the black mode for forming an image in a black area that does not include a color other than the black, the recording width is set so as to use the same number of printing elements as the used segments as the used segments, and the recording is performed. When the recording width is set so as to perform recording using a larger number of printing elements than the segments of the head and an image is formed, and when the rear end of the color area is detected during recording in the color mode, it is detected. The point where the used segment of the black head at the end of recording the rear end of the color area completes the black image formation. Held as Toggles point, the image forming control device and controls to perform image formation after the switching point of the color space back end after the recording is completed in the black mode. 5. The head position management means sets the head position control in the color mode to one-sixth of the number of print divisions of the segment in the sub-scanning direction, and forms an image in the same region by the main scan of the number of print divisions. In the color mode, the recording width is controlled so that the black area after the switching point is not recorded during recording in the color mode, and the sub-scanning direction of the black head at the first stage of forming an image after the switching point. 5. The image forming control apparatus according to claim 4, wherein the control is performed such that the main scanning is performed by the same number of times as the print division number while increasing the recording width by stopping the position. 6. The head position management means, when detecting the rear end of a color area during recording in the color mode, sets the used segment of the black head at the end of recording the detected rear end of the color area. 6. The image forming apparatus according to claim 5, wherein a point at which image formation is completed is held as a temporary switching point, and when there is an area without black within a predetermined width after the temporary switching point, the area is updated as a switching point. The image forming control device according to any one of the preceding claims.