JPH09290520A - Serial printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the use efficiency of a buffer memory. SOLUTION: A buffer memory 18 storing printing data has the memory capacity of a memory region storing the printing data corresponding to one band printed by movement in a main scanning direction and the number of regions set thereto corresponding to resolving power and a printing mode (color or white and black printing). Fort example, in the case of a color printing mode of resolving power of 720dpi, four (Y, M, C, K) memory regions corresponding to one band are formed corresponding to respective color printing heads and, in the case of a white and black printing mode of the same resolving power, four memory regions corresponding to four bands are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer capable of printing with a plurality of resolutions.

[0002]

2. Description of the Related Art An information processing apparatus such as a personal computer is usually connected to a serial printer capable of recording data such as characters and figures as visual information so that the data can be recorded on paper. It has become.
This printing device employs various printing methods such as impact method, heat-sensitive method, and ink jet method.
An ordinary printing apparatus repeats a printing process in which a print head having a plurality of recording elements of these methods is main-scanned to print one band on a sheet, and then the sheet is sub-scanned by one band width. By this, the entire surface of the paper is printed.

That is, a conventional serial printer has a print head and a buffer memory in which a storage area capable of storing print data for one band is formed. After writing the print data for one band, the print head is main-scanned while reading the print data from this storage area, and the recording element corresponding to the print data is driven to perform the print operation for one band on the paper. It is like this. When the printing operation is completed, the print data for the next band is written in the storage area of the buffer memory, and the printing operation for the next band is performed in the same manner as described above.

[0004]

However, in the above-mentioned conventional configuration, when the serial printing device has a specification in which the printing resolution can be arbitrarily changed, the storage area is set to the data capacity for printing at the maximum printing resolution. Therefore, there is a problem in that the storage area always has an empty area except when printing is performed at the maximum printing resolution, resulting in a decrease in the usage efficiency of the buffer memory.

Therefore, the present invention seeks to provide a serial printer which can always use the buffer memory with high efficiency.

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 outputs print data to the print head means while moving the print head means along the recording medium in the main scanning direction. By doing so, in a serial printer capable of printing at a plurality of resolutions, a buffer memory in which a storage area for storing print data for one band to be printed by movement in the main scanning direction is set, and an instruction to instruct resolution Control means for receiving the signal and setting the storage area in the buffer memory so that the storage capacity and the number of areas correspond to the resolution; writing means for writing print data in the storage area of the buffer memory; Reading means for reading the print data from the storage area of the buffer memory,
When a plurality of storage areas are set in the buffer memory, a switching means for sequentially switching the storage areas used for printing is provided. This gives 1
The storage area for storing print data for each band is set in the buffer memory with the storage capacity and number of areas corresponding to the resolution. When multiple storage areas are set, each storage area is used for printing while being sequentially switched. Therefore, the buffer memory can always be used with high efficiency.

According to a second aspect of the invention, there is provided the serial printer according to the first aspect, wherein the switching means causes the writing means and the reading means to perform writing in different storage areas. It is characterized by switching as follows. As a result, while the print data is being read from the specific storage area, the print data from the next time onwards can be written to other storage areas, so waiting for the completion of writing the print data The time can be shortened, and as a result, the apparent printing speed can be increased.

A third aspect of the present invention is the serial printer according to the second aspect, characterized in that the control means sets the number of regions to 3 or more when the resolution is low.
As a result, while the print data is being read from the specific storage area, it is possible to sequentially write the print data for the next and subsequent storage areas to the remaining two or more storage areas. The speed can be increased.

A fourth aspect of the present invention is the serial printer according to the first aspect, wherein the control means receives from an external device a portion other than the storage area set by the number of areas corresponding to the resolution. It is characterized by setting a reception buffer area for storing print data. As a result, the print data for the next time and thereafter can be continuously stored in the reception buffer area, so that the waiting time required for receiving the print data can be shortened and the apparent printing speed can be improved.

A fifth aspect of the present invention is the serial printer according to the first aspect, wherein the print head means comprises a plurality of print heads for printing different colors.
The control means forms a plurality of storage areas corresponding to the respective print heads when receiving the instruction signal of the multi-color printing mode, and 1 when receiving the instruction signal of the single-color printing mode.
It is characterized by forming a plurality of storage areas corresponding to one print head. As a result, the storage area in the multi-color printing mode and the storage area in the single-color printing mode are set to overlap each other on the same address of the buffer memory. It can also be used efficiently.

According to a sixth aspect of the present invention, there is provided the serial type printing apparatus according to the fifth aspect, wherein the print head means comprises yellow, magenta, cyan and black print heads, and monochromatic printing is performed. In this case, a black print head is used. As a result, by combining the print heads of the respective colors, it is possible to perform full-color printing in the multi-color printing mode and to use it as a general-purpose printer dedicated to a single color in the single-color printing mode.

According to a seventh aspect of the present invention, there is provided the serial printer according to any one of the first to sixth aspects, wherein the writing means, the reading means, and the control means are integrated by a hardware logic circuit. It is characterized by being configured. As a result, the control for setting the storage area in the buffer memory and the writing / reading to / from the storage area can be performed independently of other print control controlled by the CPU or the like.
It is possible to reduce the load on the PU and use an inexpensive CPU.

The invention of claim 8 is the serial type printer according to claim 7, wherein the print head means is an ink jet head. This makes it possible to perform printing with excellent quietness.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. The serial printer according to the present embodiment is connected to an information processing device 1 such as a personal computer as shown in FIG. The information processing device 1 is used for inputting and instructing data, a processing device body 2 having a built-in auxiliary storage device such as a magnetic disk device and a central processing unit, a CRT (cathode-ray tube) 3 for displaying data and the like on a screen. It has a keyboard 4 and a mouse 5 and is connected to a printer 7 which is a serial type printing device via a printer cable 6 of Centronics specification, for example.

As shown in FIG. 3, the processing apparatus main body 2 has a window system 8 as an operating system (OS). Window system 8
Includes an application 9 such as a document creation program, a font driver 10 for managing fonts, a CRT driver 11 for managing the CRT 3, a keyboard driver 12 for managing the keyboard 4, a mouse driver 13 for managing the mouse 5, and a printer 7. Printer driver 1 to manage
4 and one or more applications 9 can be executed simultaneously.

The printer driver 14 selects a preselected color printing mode (multicolor printing mode) when a "print execution" menu is specified for the data displayed on the screen of the CRT 3, for example. ) Or dot image data in black and white print mode can be formed. For example, in the case of color print mode, yellow (Y ), Magenta (M), cyan (C), and black (K) dot image data (pixel data arranged in a dot matrix in the horizontal and vertical directions) is formed, and these dots are formed. Interface the image data as print data in 8-bit units (I /
The F) unit 15 outputs the data sequentially.

The print data output in the raster scan format as described above is printed by the printer 7 as shown in FIG.
Is input to the I / F (interface) unit 16 of. The printer 7 includes a printer controller 17 and a buffer memory 1 that can set print buffers (storage areas) for yellow (Y), magenta (M), cyan (C), and black (K), for example.
8, a print head drive unit 19, and a motor drive unit 20. The motor drive unit 20 is connected to the CR motor 22 and is configured to rotate the CR motor 22 forward and backward. On the other hand, the print head drive unit 19
Are print heads 21a to 21 for yellow (Y), magenta (M), cyan (C), and black (K).
d (print head means). In each of the print heads 21a to 21d, nozzles (not shown) that eject ink by displacement of the piezoelectric elements are arranged in the sub-scanning direction for 64 channels, for example, and the piezoelectric elements of these nozzles are displaced. As described above, the drive voltage from the print head drive unit 19 is applied to each.

The above print heads 21a to 21d are shown in FIG.
As shown in, the carriage 23 is fixed to the paper 25 so that the ejection direction of the ink is at a predetermined angle with respect to the paper 25. A guide shaft 24 horizontally provided in the main scanning direction is movably inserted into the carriage 23, and a scanning belt 26 driven by the CR motor 22 is connected to the carriage 23. The motor 22 causes the carriage 23 to move forward and backward along the guide shaft 24 in the main scanning direction so as to perform main scanning of the print heads 21a to 21d while maintaining a constant distance from the paper 25.

On the lower surface of the carriage 23, an encoder element 2 including a non-contact type sensor such as an optical type or a magnetic type is provided.
7 are provided. In the detection direction of the encoder element 27, a timing slit 28 having a large number of slit portions 28a at equal intervals is provided in parallel with the guide shaft 24.
At the same time, when it moves in the main scanning direction, the slit portion 28a of the timing slit 28 is detected and output as an encoder signal.

The above encoder signal is input to the printer controller 17, as shown in FIG. The printer controller 17 includes a print timing generation unit 34, a buffer control unit 35, a compressed data decompression (hereinafter referred to as “decompression”) decompression unit 37, and a CPU unit 38.
(Switching unit), I / F control unit 42, and print control unit 4
Three. The print timing generation unit 34, the buffer control unit 35, the compressed data decompression unit 37, the I / F control unit 42, and the print control unit 43 are implemented by a hard logic circuit such as an ASIC (Application Specific Integrated Circuit). The integrated ASIC section 39 is configured.

As shown in FIG. 1, the print timing generating section 34 constituting the ASIC section 39 uses the above-mentioned encoder signal as a reference to generate a print clock (a timing signal serving as a reference for reading data from the buffer memory 18 or the like). Etc.) and outputs the print clock to the buffer control unit 35 and the print control unit 43. The buffer control unit 35 includes a DMA controller 40 (writing means / reading means) for inputting / outputting data to / from the buffer memory 18, and an address generator 41 (designating a read / write buffer address of the buffer memory 18). (Writing means, reading means, control means).

The above address generator 41 is a CP
A resolution designating signal and a mode designating signal are input from the U section 38. The resolution (180 dpi, 360 dpi, 720 dpi) is recognized by the resolution designating signal, and the print mode (color printing mode, black and white printing by the mode designating signal. Mode).
The print mode is one of the print heads 21a to 21d for yellow (Y), magenta (M), cyan (C), and black (K) instead of the monochrome print mode.
It is also possible to use a single-color printing mode in which printing is performed by using one. Then, the address generator 41 determines the storage capacity and the number of areas according to the combination of the recognized resolution and print mode, and makes the print buffer of each combination exist at the same address to effectively use the buffer memory 18.

That is, the address generator 41 shown in FIG.
As shown in, the resolution (180 dpi, 360 dpi,
720 dpi), a print mode (color print mode, black and white print mode), and an address memory storing a buffer address. The buffer memory 18 has a minimum storage capacity for one band in the high-resolution color printing mode, and the address generator 41 has seven
When the high-resolution color print mode of 20 dpi is recognized, as shown in FIG. 7 (f), yellow (Y), magenta (M), cyan (C), and black (K) By setting the first buffer address, the print buffer for one band (IB which consists of four storage areas corresponding to the print heads 21a to 21d of each color)
-1 "YMCK") is formed in the buffer memory 18. Here, the storage capacity of each storage area corresponds to a resolution of 720 dpi.

In the case of monochrome printing, the number of print heads is 1.
As much as / 4, it is possible to form four times as many print buffers in the buffer memory having the same capacity. When the address generator 41 recognizes the black-and-white print mode of 720 dpi as shown in FIG. 7C, the first to fourth buffer addresses for black (K) should be set in the buffer memory 18 of the same capacity. 4 storage areas corresponding to one print head 21d for black (K), that is, print buffers for four bands (IB-1, IB-2, IB-3, IB-4).
) Is formed in the buffer memory 18. Similarly, 360
In the case of the medium resolution color print mode of dpi, the storage capacity required for each storage area is also halved because the resolution is halved, and a double print buffer should be formed in the same buffer memory. You can By setting the first and second buffer addresses in FIG. 6 in this mode, two bands of print buffers (IB-1 “YMCK”, IB-2 “YMCK”) for 4 colors are set as shown in FIG. 7E. ), In the case of the monochrome printing mode of the same resolution, as shown in FIG.
Form print buffers (IB-1 to IB-8) for bands. In the low resolution color print mode of 180 dpi, a print buffer for 4 bands is formed as shown in FIG. 6D, and in the monochrome print mode, a print buffer for 16 bands is formed.

On the other hand, as shown in FIG.
Outputs a print data transfer clock, a print clock, and print data to the print head drive unit 19 described above. Then, the ASIC unit 39 having such a configuration executes the print data writing process and the print data reading process with respect to the print buffer of the buffer memory 18 formed according to the combination of the resolution and the print mode. ing.

In the writing process to the buffer memory 18, the print data (I / F data, I / F data, which has passed from the I / F unit 16 through the I / F control unit 42 and the compressed data decompression unit 37) is used.
I / F latch data). When the STB (strobe) signal is received together with the print data (I / F data) from the I / F unit 16, the I / F control unit 42 sends the reception request signal to the centro data reception interrupt gate 29 including an AND circuit. By outputting, the CPU 38 is made to execute the reception interrupt processing according to the command existing at the head of the data group.

That is, when the received command is the resolution designating command and the mode designating command, the CPU section 38 designates the resolution (18) designated by these commands.
0 dpi, 360 dpi, 720 dpi) and a resolution designating signal indicating a printing mode (color printing mode, black and white printing mode) and a mode designating signal are output to the address generator 41, and reception interrupt processing for setting the buffer address to the address generator 41 is performed. Ready to run. If the received command is a transfer command, the DMA controller 40 and the compressed data decompression unit 37 receive subsequent data from the information processing device 1 by the DMA controller 40, and the DMA controller 40 and the compressed data decompression unit 37 receive predetermined data from the buffer memory 18. A reception interrupt process for outputting a DMA command to be stored in the area is executed.

The I / F control unit 42 outputs a reception request signal to the compressed data decompression unit 37, and responds to this by receiving an I / F control signal from the compressed data decompression unit 37. Print data (I / F
Latch data) is output to the compressed data decompression unit 37, and the output state of the print data is maintained so that the decompression unit 37 can capture the data and the BUSY signal is also transmitted via the I / F unit 16. The data is output to the information processing device 1 and is set to wait for data transmission.

The compressed data decompression unit 37 to which the print data (I / F latch data) is input from the above I / F control unit 42 is from the time when the DMA command is input until the transfer for one raster is completed. During the period, the gate 29 is closed so that the CPU 38 does not receive a reception interrupt. Further, the compressed data decompression unit 37 determines whether or not the print data is compressed, and when it is not compressed, the print data (I / F latch data) input from the I / F control unit 42 is DMAed. Controller 4
Each time the data transfer notification signal is input from 0, it is sequentially output. On the other hand, when the print data is compressed, one print data (I / F latch data) input from the I / F control unit 42 is DM-converted by the number of compression times.
Each time a data transfer notification signal is input from the A controller 40, it is repeatedly output.

The operation of the serial type printing apparatus having the above structure will be described. First, as shown in FIG. 2, when the "print menu" is designated by the keyboard 4 or the mouse 5, the window system 8 operates the printer driver 14 as shown in FIG.
A format screen for setting "resolution", "print mode", "font", etc. is displayed on the screen of RT3. Then, for example, when the resolution and the print mode are designated, the resolution designation command and the mode designation command indicating the designated resolution and the print mode are output to the I / F unit 16 as shown in FIG. And these commands are processed as I / F data by the I / F control unit 42.
After being output to the CPU, it is taken in by the CPU unit 38 which is in the interrupt enabled state by the centro data reception interrupt gate 29.

When commands are fetched into the CPU section 38, the contents of these commands (resolution and print mode)
After being recognized, the resolution designating signal and the mode designating signal set to correspond to the command contents are output to the address generator 41. When the address generator 41 recognizes that, for example, the medium resolution and the color printing mode of 360 dpi are designated by the resolution designation signal and the mode designation signal, as shown in FIG. 6, yellow (Y) and magenta (M) colors are set. , Cyan (C), and black (K) first and second buffer addresses will be set. As a result, as shown in FIG. 7, the buffer memory 18 stores 2 for each color.
Print buffer for bands (IB-1 “YMCK”, IB-2 “YM
CK ”) will be formed.

Next, on the screen of CRT 3 in FIG.
When "Print execution" is specified, the dot image data formed by reading data consisting of characters and figures to be printed stored in a magnetic disk device or memory (not shown) or a combination thereof in a raster scan format has 8 bits. The data is output in raster order as print data in units. Then, as shown in FIG. 1, the print data of each color is transferred to the I / F unit 16 of the printer 7 via the I / F unit 16.
When the data is input to the control unit 42 and recognized by the CPU unit 38 as print data having a data transfer command,
A DMA command is sent from the CPU section 38 to the DMA controller 40.
Etc., and is output to the first print buffer (IB-1 of the buffer memory 18 set by the address generator 41).
"YMCK") for the first buffer address (00000H (Y), 0
The print data of each color is sequentially written from 8000H (M), 10000H (C), 18000H (K)).

After that, when the write operation of the print data for each color is performed for one band (64 rasters), the CP
A preparation instruction for printing is output from the U unit 38 to the DMA controller 40, and the carriage 2 shown in FIG.
3 will be started. Then, the carriage 23 reaches the print start position, and the print timing generation unit 3
4 outputs a print clock, the DMA controller 40 in response to this outputs the print data of each color from the first print buffer (IB-1 “YMCK”) of the buffer memory 18 and outputs the yellow (Y ), Magenta (M), cyan (C), and black (K) print dots are formed on the paper 25.

While the printing for one band is being performed as described above, the next print data is input to the CPU section 38, and when it is recognized that this print data has a data transfer command, DMA command from the CPU unit 38 is DMA
It will be output to the controller 40 and the like. And
For the second print buffer (IB-2 “YMCK”) of the buffer memory 18 set by the address generator 41, the second buffer address (20000H (Y), 28000H (M), 30000)
From H (C), 38000H (K)), print data of each color will be written in order. After that, when the writing of the print data to the second print buffer (IB-2 “YMCK”) is completed, the print data is read from the second print buffer (IB-2 “YMCK”) and the next band is printed. Meanwhile, the print data is written to the first print buffer (IB-1 “YMCK”).

As a result, the time required for the print data write operation and the print data read operation (print operation)
When the time required for is equal to
Printing is performed without interruption by alternately performing the write operation and the read operation of print data for the first print buffer (IB-1 “YMCK”) and the second print buffer (IB-2 “YMCK”). Therefore, it is possible to complete printing in a shorter time than when printing is performed using one print buffer.

When the time required for the print data write operation and the time required for the print data read operation (print operation) are different, that is, when the write time is shorter than the read time, the CPU section 38 causes the print operation. When there is a time during which nothing is done until the end of, and the writing time is longer than the reading time, the printing operation is stopped. However, when there are four or more print buffers as shown in FIGS. 7A to 7D, as shown in FIG.
4 layers print buffer for each color (IB-1 "YMCK",
IB-2 “YMCK”, IB-3 “YMCK”, IB-4 “YMCK”) are formed in the buffer memory 18. Therefore, in this case, as shown in FIG. 9, even if the time required for the print data write operation and the time required for the print data read operation (print operation) are different, these time differences are Since each is absorbed by the fourth print buffer, printing is completed in a shorter time than in the case of the two-layer print buffer. This operation can be realized if there is a print buffer for at least 3 bands. In this case, the time of writing to the first print buffer is the position shown by the chain line.

Further, in this embodiment, as shown in FIG. 7, the print buffer is formed in the entire memory area of the buffer memory 18, but the present invention is not limited to this. As shown in 10, the upper limit of the number of areas of the print buffer may be set to two layers, and the reception buffer may be set to the remaining memory area. With this configuration, the print data and commands for the next time onward can be continuously stored in the receive buffer, so the waiting time required for receiving print data is shortened and the apparent print speed is improved. Can be made.

[0038]

According to the first aspect of the present invention, print data is output to the print head means while moving the print head means in the main scanning direction along the recording medium, whereby printing can be performed at a plurality of resolutions. In serial printer,
A buffer memory in which a storage area for storing print data for one band to be printed by movement in the main scanning direction is set, and a storage capacity and the number of areas corresponding to the resolution upon receiving an instruction signal for instructing the resolution Control means for setting the storage area in the buffer memory, writing means for writing print data into the storage area of the buffer memory, reading means for reading print data from the storage area of the buffer memory, and the buffer memory. When a plurality of storage areas are set, a switching means for sequentially switching the storage areas used for printing is provided. This gives 1
The storage area for storing print data for each band is set in the buffer memory with the storage capacity and number of areas corresponding to the resolution. When multiple storage areas are set, each storage area is used for printing while being sequentially switched. Therefore, it is possible to always use the buffer memory with high efficiency.

According to a second aspect of the invention, there is provided the serial printer according to the first aspect, wherein the switching means causes the writing means and the reading means to read different storage areas. The configuration is such that switching is performed as follows. As a result, while the print data is being read from the specific storage area, the print data from the next time onwards can be written to other storage areas, so waiting for the completion of writing the print data The time can be shortened, and as a result, the apparent printing speed can be increased.

A third aspect of the present invention is the serial printer according to the second aspect, wherein the control means sets the number of areas to 3 or more when the resolution is low. As a result, while the print data is being read from the specific storage area, it is possible to sequentially write the print data for the next and subsequent storage areas to the remaining two or more storage areas. The effect is that the speed can be increased.

According to a fourth aspect of the present invention, in the serial printer according to the first aspect, the control means receives from an external device a portion other than the storage area set by the number of areas corresponding to the resolution. The configuration is such that a reception buffer area for storing print data is set. As a result, the print data from the next time onward can be continuously stored in the reception buffer area, so that the waiting time required for receiving the print data can be shortened and the apparent printing speed can be improved. Play.

A fifth aspect of the present invention is the serial printer according to the first aspect, wherein the print head means comprises a plurality of print heads for printing different colors,
The control means forms a plurality of storage areas corresponding to the respective print heads when receiving the instruction signal of the multi-color printing mode, and 1 when receiving the instruction signal of the single-color printing mode.
This is a configuration for forming a plurality of storage areas corresponding to one print head. As a result, the storage area in the multi-color printing mode and the storage area in the single-color printing mode are set to overlap each other on the same address of the buffer memory. The effect is that the usage efficiency can be made high.

According to a sixth aspect of the present invention, there is provided the serial type printing apparatus according to the fifth aspect, wherein the print head means comprises yellow, magenta, cyan and black print heads, and monochrome printing is performed. In this case, a black print head is used. As a result, by combining the print heads of the respective colors, it is possible to perform full-color printing in the multicolor printing mode and to use the printing head as a general monochromatic printing device in the single-color printing mode.

According to a seventh aspect of the present invention, there is provided the serial printer according to any one of the first to sixth aspects, wherein the writing means, the reading means, and the control means are integrated by a hardware logic circuit. It is a configured configuration. As a result, the control for setting the storage area in the buffer memory and the writing / reading to / from the buffer memory can be performed independently of the other print control controlled by the CPU or the like, reducing the load on the CPU and reducing the cost of the CPU. There is an effect that can be used.

The invention of claim 8 is the serial type printer according to claim 7, wherein the print head means is an ink jet head. As a result, there is an effect that it is possible to perform printing with excellent quietness.

[Brief description of drawings]

FIG. 1 is a block diagram of an ASIC unit.

FIG. 2 is a perspective view of a serial printer to which an information processing device is connected.

FIG. 3 is a block diagram of an information processing device and a serial printer.

FIG. 4 is a block diagram showing the overall configuration of a serial printer.

FIG. 5 is a perspective view of a main part of a serial printer.

FIG. 6 is an explanatory diagram showing contents of data stored in an address generator.

FIG. 7 is an explanatory diagram showing a state of a print buffer formed in a buffer memory.

FIG. 8 is an explanatory diagram showing an operating state when a two-layer print buffer is used.

FIG. 9 is an explanatory diagram showing an operating state when a four-layer print buffer is used.

FIG. 10 is an explanatory diagram showing contents of data stored in an address generator.

[Explanation of symbols]

 1 Information Processing Device 7 Printer 14 Printer Driver 16 I / F Unit 17 Printer Controller 18 Buffer Memory 19 Print Head Drive Unit 20 Motor Drive Unit 21 Print Head 22 CR Motor 23 Carriage 24 Guide Axis 25 Paper 26 Scanning Belt 27 Encoder Element 28 timing slit 35 buffer control unit 37 compressed data decompression unit 38 CPU unit 39 ASIC unit 40 DMA controller 41 address generator 43 print control unit 37 compressed data decompression unit

Claims (8)

[Claims] 1. A serial type printer capable of printing at a plurality of resolutions by outputting print data to the print head means while moving the print head means in the main scanning direction along a recording medium. A buffer memory in which a storage area for storing print data for one band to be printed by movement in the scanning direction is set, and a storage capacity and the number of areas corresponding to the resolution upon receiving an instruction signal for instructing the resolution Control means for setting the storage area in the buffer memory; writing means for writing print data in the storage area of the buffer memory; reading means for reading print data from the storage area of the buffer memory; When a plurality of storage areas are set, a switching means for sequentially switching the storage areas used for printing is provided. Serial-type printing apparatus to be. 2. The switching means switches so that writing by the writing means and reading by the reading means are performed in different storage areas.
The serial printer described. 3. The serial printer according to claim 2, wherein the control unit sets the number of areas to 3 or more when the resolution is low. 4. The control means sets a reception buffer area for storing print data received from an external device in a portion other than the storage area set by the number of areas corresponding to the resolution. The serial printer according to 1. 5. The print head means comprises a plurality of print heads for printing different colors, and the control means responds to each print head when receiving an instruction signal of a multicolor print mode. 2. The serial printer according to claim 1, wherein the plurality of storage areas are formed while the plurality of storage areas corresponding to one print head are formed when the instruction signal of the monochrome printing mode is received. . 6. The print head means comprises yellow, magenta, cyan, and black print heads, and a black print head is used for single-color printing. Item 5. The serial printer according to Item 5. 7. The serial printer according to claim 1, wherein the writing unit, the reading unit, and the control unit are integrally configured by a hardware logic circuit. . 8. The serial printer according to claim 7, wherein the print head unit is an inkjet head.