JP2734140B2 - Serial printer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to processing of print data for driving a serial printer.

2. Description of the Related Art Conventionally, in a so-called line printer such as an electrophotographic printer represented by a laser printer or a thermal line printer, printing is performed based on a print image of one raster (line) developed in a raster direction. The printing of one sheet is performed by feeding the sheet in the vertical direction, that is, the direction perpendicular to the raster direction. Therefore, in order to drive the printing mechanism, a raster image buffer for temporarily storing the print image stores the print image developed in the raster direction separately.

On the other hand, in a serial printer typified by a wire dot system or the like, the print head is moved in the horizontal direction with respect to the paper, that is,
That is, the printing operation for one sheet is performed by repeating the operation of printing a plurality of pixels in the column direction, printing one line, and then feeding the sheet in the vertical direction.
Therefore, an image developed in the vertical direction, that is, in the column direction, is stored in the column image buffer as a basic unit.

For this reason, even if the same print result is obtained, the line printer and the serial printer use a completely different method from the beginning to develop a print image in a buffer and then drive the printing mechanism to perform printing.

Further, the line printers are used as page printers and color printers capable of handling high-resolution graphics processing, while the serial printers are used for low-resolution character printers. For this reason, the line printer and the serial printer have been independently developed from the beginning as completely different models.

[Problems to be Solved by the Invention] However, today, the technology of serial printers has remarkably improved, and high resolution and color printing have been easily achieved. Therefore, even with a serial printer, it is possible to achieve the same print quality as a laser printer, a color line printer, or the like.

However, the line printer and the serial printer differ in the final memory development for driving the printing mechanism as described above. For this reason, after all, the page graphics processing section, which is the most important part and requires the most complicated program, has to be created completely from scratch by the line printer and the serial printer. In other words, no matter how sophisticated the page printer software that has been built up, it could not be used at all in the development of a new serial printer that can handle graphics processing.
Therefore, a great deal of effort and time was required to complete a stable serial printer using bug-free software.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is intended to directly use a raster image developed in a memory by a graphics processing unit of a line printer, convert the raster image into a column image, and print serially. Accordingly, it is an object of the present invention to provide a serial printer with stable quality in a minimum development period and a minimum development cost by using the graphics processing unit of the line printer without any change.

Means for Solving the Problems In order to achieve this object, a serial printer according to the present invention has an interface for receiving data from the outside, and develops a print image in a raster direction according to data received via the interface. A graphics processing unit, a print image developed in the raster direction by the graphics processing unit is stored in a bitmap format, and a raster image buffer in which writing and reading are performed in a raster system. A column image buffer for storing the print image in a format developed in the column direction so as to be supplied to the print head, and a raster / column conversion unit for converting the print image stored in the raster image buffer into a column image and storing the column image in the column image buffer And its Raster /
A printer driver for supplying a column image stored in a column image buffer by a column conversion unit to the print head and performing a serial print operation.

[Operation] In the serial printer of the present invention having the above-described configuration, data received from the outside via the interface is developed in the raster direction by the graphics processing unit and written into the raster image buffer in a raster-only manner. The print image stored in the raster image buffer is read out by the raster / column conversion unit, converted into a column image of a format developed in the column direction, and stored in the column image buffer. Further, the column image stored in the column image buffer is read by the printer driver unit, supplied to the print head in a format developed in the column direction, and serially printed on a print medium.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In the present embodiment, the control circuit and control software of a ready-made laser printer, which is a typical printer of the raster system, are diverted to the serial printer of the ink jet system. First, the configuration of a portion related to the present invention in this ready-made laser printer will be described with reference to FIG.

The control unit 21 includes a CPU and a ROM for its operation.
It is composed of RAM and other control circuits. The raster image buffer 22 stores a print image developed in the raster direction in a bitmap format. In the character generator 23, a print image for printing characters, symbols, and the like is expanded in the raster direction and stored in advance. The interface 24 receives various print commands from outside. The laser printer engine 25 includes a paper feed mechanism, a developing mechanism, an optical system mechanism, and the like, and performs printing on paper. Further, the control unit 21 performs various processes described below using a plurality of software modules. A system management 21a, which includes a program for managing status management of the entire system, receiving data from the interface 24 and executing other software modules, and controlling the entire system, and an interface 24
A command interprinter 21b for interpreting various commands received from the printer and prompting the processing thereof, a print image processing 21c as graphics processing for sequentially developing a print image in the raster direction according to a print command and storing the print image in a raster image buffer 22 , Laser printer engine 2
5 to transfer the print data of the raster image buffer 22 to the laser printer engine 25 for printing.
Done in Next, the configuration of a serial printer using an ink jet system according to this embodiment will be described with reference to FIG.

In this embodiment, basically, the hardware configuration of the above-described laser printer, such as electronic components and memory mapping, is directly ported. The control unit 11, raster image buffer 12, character generator 13, and interface 14 in FIG. 1 are the same as the corresponding blocks in FIG.

Next, components different from the configuration in FIG. 2 will be described. First, the laser printer engine is replaced with an ink jet serial printer engine 15. Also,
Column image buffer for converting part of the contents of the raster image buffer 12 into column images and storing them
16 have been added. The command interpreter 11 in the software module in the control unit 11 is also provided.
The command interpreter 21b and the print image processing 21c shown in FIG. 2 are used as they are in the b and print image processing 11c without any modification. Further, the printer driver 21d is replaced by a serial printer driver 11d. Also, a raster / column conversion 11e is newly added. Most of the system management 11a uses the system management 21a of the laser printer shown in FIG. 2 as it is, and only a part of the system management 11a is modified so as to match the system configuration of the serial printer.

This ink jet serial printer has a print head having eight orifices. Then, while the print head moves one line in the printing line direction on the printing paper, ink is ejected from eight orifices based on the column image in the column image buffer 16 and the ink is jetted out.
The configuration is such that printing for the lines is performed serially.

Next, a processing flow in the serial printer having such a configuration will be described in detail with reference to FIG.

FIG. 3 is a flowchart in which the processing of the main part from the power ON of the printer to the printing operation is extracted. Power ON
Then, at step 100, the system is initialized. This is a part of the system management 11a, and the software for the laser printer is partially modified so as to be compatible with the serial printer system. Next, the process proceeds to step 101, where the interruption is permitted so that the system is managed by the interval timer interruption. This interrupt processing unit is partially modified for the laser printer in accordance with the system. Next, the process proceeds to step 102, where the interface interrupt is permitted to receive data from the interface by the interrupt processing. This interrupt processing is the same as the processing of the laser printer. Next, after performing other necessary fine processing, the process enters a print processing loop.

Here, first, in step 103, the print command, print data, and system information stored in the buffer / register area of the RAM in the control unit 11 are checked by each interrupt processing, and processing according to these information is performed. . The print command and print data checked here are those received by the interface interrupt. The system information is input by an interval timer interrupt. Then go to step 104,
It is determined whether the system is ready for printing. If the printing process is not possible, the process proceeds to step 105, where other processes currently required are performed. Next, the process goes to step 104 again, and it is determined whether or not the system is in a state capable of performing a printing process. If the print processing is possible, the process proceeds to step 106.
Here, a print image developed in the raster direction based on the print data received by the interface interrupt,
That is, the raster images are sequentially written to the raster image buffer 12. The process of writing the received print data from step 103 to step 106 as a raster image expanded in the raster direction to the raster image buffer 12 in this manner, except for a part of the processing for the system information in step 103, is performed by a laser printer. The process in the above is diverted as it is.

Next, go to step 107, where the raster image buffer 12
In the above, it is determined whether or not the print image developed in the raster direction has been stored in an amount required for conversion to the column image. That is, it is determined whether or not the raster image for the raster required for the printing operation is stored in the raster image buffer 12 while the inkjet print head moves one line in the printing line direction on the printing paper. You. The print head of the ink jet system in this embodiment has eight orifices, and when raster images of eight rasters or more are stored, conversion to a column image becomes possible. If a sufficient amount of raster images has been stored, the process proceeds to step 108, where the raster images are converted into column images. Then step 109
Then, it is determined whether or not a column image of an amount necessary for printing performed by one print line, that is, one stroke of the print head in the print line direction, is stored in the column image buffer.

On the other hand, if the storage amount of the raster image in the raster image buffer 12 is insufficient for conversion to the column image in step 107, the process also proceeds to step 109, and the above-described determination is performed.

Here, if the stored column image has not yet reached one print line, the process proceeds to step 103 again, and the processing up to step 108 is performed to accumulate the column image. On the other hand, if it is determined in step 109 that the column image for one print line is stored,
Go to 110. Here, it is determined whether or not the serial printer engine 15 is in a ready state. Here, if the serial printer engine 15 is not in the ready state, the procedure goes to step 103 again. Then, accumulation of the column images from step 103 to step 109 is performed until the serial printer engine 15 becomes ready. On the other hand, if the serial printer engine 15 is in the ready state, the process proceeds to step 120. Here, the column image buffer 16 is controlled by the serial printer driver 11d.
The serial printer engine 15 is driven based on the column image stored in the printer, and printing for one print line is performed by serial processing. When the printing for one print line is completed, the process goes to step 103 again. And step 1
By the processing from 03 to step 120, the column image of the next print line is printed.

Next, the raster / column conversion in step 108 of FIG. 3 will be described in detail with reference to the drawings.

First, FIG. 4 shows a raster / column conversion circuit. In the figure, each data input terminal D0-D7 of the first through eighth latch circuits 31-38 for storing bit patterns developed in the raster direction is paired with data buses DX0-DX7 of the CPU of the control unit 21, respectively. 1 connected. Further, each clock terminal Ck of each of the latch circuits 31 to 38 is connected to a strobe signal line whose signal pattern is determined by control of the CPU. Each of the latch circuits 31 to 38 latches the bit data of the input terminals D0 to D7 at the timing when the strobe signal CE from the strobe signal line becomes valid and outputs the bit data to each of the output terminals Q0 to Q7. And the first to eighth
Output terminals Q0 to Q7 of the latch circuits 31 to 38 are respectively connected to input terminals D0 to D7 of first to eighth multiplexers 39 to 46 which perform bit-wise output. The bit select terminals S0 to S2 of the multiplexers 39 to 46 are connected to signal lines whose signal patterns are determined by the control of the CPU. Based on the signal pattern of the select signal SEL from this signal line, any one of the eight input bits D0 to D7 is transmitted from each of the first to eighth multiplexers 39 to 46 to the data bus of the CPU. Output as ~ DY7.

In the raster image buffer 12 shown in FIG. 5, in step 106 of FIG. 3, raster images developed in the raster direction are sequentially written in bitmap format in ascending order of address. In other words, when the matrix bit pattern stored in the character generator 13 is indicated by, for example, 8 rows and 8 columns, the matrix bit pattern is indicated in the raster image buffer 12 by being divided in the column direction (horizontal direction, that is, the printing line direction). Are sequentially stored as row bit patterns for every 8 bits. For example, as shown in FIG. 6, the print pattern is "H",
If "I", ..., image buffer for printing
12, row bit patterns obtained by sequentially dividing the bit patterns corresponding to "H", "I",... In the column direction are stored as shown in FIG.

Next, the operation of the raster / column conversion by the above configuration will be described.

First, the CPU operates the raster image buffer 12 shown in FIG.
8 bit row bit pattern "0000" from "0000"
0000 ”is read. Next, this row bit pattern is output to the data bus, and only the strobe signal CE0 is made valid. Then, only the first latch circuit 31 is selected. In response, the first latch circuit 1 receives the row bit pattern from the CPU and outputs this row bit pattern from the output terminals Q0 to Q7.

Similarly, the CPU stores the row bit pattern `` 01000100 '' stored at address 0100, the row bit pattern `` 01000100 '' stored at address 0200, and the row bit pattern `` 01000100 '' stored at address 0300 at address 0400. The row bit pattern `` 01111100 '' stored at address 0500, the row bit pattern `` 01000100 '' stored at address 0600, the row bit pattern `` 01000100 '' stored at address 0700, and the row bit pattern `` 01000100 '' stored at address 0700 Second to eighth latch circuits
Store in 32-38.

Subsequently, the CPU controls the signal pattern of the select signal SEL to output the bit signals DY0 to DY7 input to the input terminal D0 from the first to eighth multiplexers 39 to 46. In the first process,
The bit signal DY0 output from each of the multiplexers 39 to 46
DY7 correspond to the first bit of each row bit pattern. The bit signal sequence of DY0 to DY7 in this example is
It becomes “00000000”. This signal sequence corresponds to the column bit pattern (vertical bit pattern) of the first column of the matrix bit pattern corresponding to “H”.

Next, the CPU reads the column bit pattern “00000000”. Next, the CPU stores the read column bit pattern in the seventh column.
As shown in the figure, for example, 1000 of the column image buffer 16
Write to the address.

Similarly, the CPU sequentially controls the signal pattern of the select signal line SEL. In this way, the CPU
The second consisting of bit signals of the same bits 1 to 38
Column bit patterns "01111111", "0000100"
0 "," 00001000 "," 00001000 "," 01111111 "," 0
0000000 "and" 00000000 "to each multiplexer 39-46
Are read as bit signal trains of bit signals DY0 to DY7 output from the CPU, and their column bit patterns are sequentially written from address 1001 onward in the column image buffer 16 as shown in FIG. As a result, 10 of the column image buffer 16
From address 00, an 8-bit column bit pattern is stored as shown in FIG.

Thus, one column bit pattern of 8 bits stored in the column buffer 16 constitutes one column image. In other words, each bit of this 8-bit column bit pattern corresponds to each orifice as print data for controlling ink ejected from eight orifices in an ink jet print head. The fact that the column image thus converted has been stored in the column image buffer 16 for one print head stroke in one print line is shown in the step of FIG.
If it is determined in 107, the print head is driven according to the column image for one print line, and printing is performed.

In addition, an ink jet serial printer has a print head having more than eight orifices, or a serial printer is a printing method such as a wire dot method or a thermal method and has more than eight printing elements. 8 as a single column image
A column bit pattern consisting of more bits than bits may be required. In such a case, the number of latch circuits and multiplexers of the raster / column conversion circuit shown in FIG. 4 may be increased. This makes it possible to easily form a column image composed of column bit patterns composed of as many bits as the number of latch circuits increased. Alternatively, the first to eighth latch circuits 31 to
After writing the column bit pattern of the 38 same bit signals into the column image buffer 16, before writing the next same bit signal, the first to eighth bit signals are written.
The bit pattern of the latch circuits 31 to 38 may be rewritten to a row bit pattern further advanced in the column direction (vertical direction), and a column bit pattern based on the same bit signal as in the above-described processing may be written to the column image buffer 16. .
This makes it possible to obtain a column image composed of 16-bit column bit patterns without increasing the number of latch circuits and multiplexers. In order to obtain a column bit pattern including more bits, rewriting of the bit pattern of the latch circuit and reading of a bit signal of the same bit may be repeated.

As described above, in the serial printer of the present embodiment, of the software modules, the command interpreter 11b and the print image processing 11c are diverted from the existing laser printer without changing the software module. Although a part of the software module of the serial printer system management 11a is modified so as to be suitable for the serial printer system, the laser printer system management 21a is mostly used. In this way, the already completed main processing of the laser printer can be diverted to the serial printer as it is, so that a product with stable quality can be completed in a minimum period and at a minimum cost. In particular, as for the print image processing 11c as graphics processing that requires complicated processing, the print image processing 21c that has already been completed in the laser printer and from which defects such as bugs have been removed can be used as it is. This greatly contributes to providing a serial printer with stable quality in a short period of time and at low cost.

In the print head of this embodiment, a plurality of printing elements are arranged in the column direction. However, this arrangement direction is not necessarily required to be perpendicular to the printing row direction, but is inclined with respect to the vertical direction. Even function as a serial printer.

Further, even if the print head has only one print element, and this one print element is deviated perpendicularly to the print line direction or deviated in a predetermined angle direction, the print head is still serial. Functions as a printer. An example of this is an ink jet print head provided with only one orifice. The ink jet from the orifice is switched to a direction perpendicular to the print line direction or at a predetermined angle, while the print head is It is conceivable that the printing is performed while moving in the printing line direction.

Further, in the present embodiment, the hardware configuration of the serial printer is realized exactly the same as the configuration of the existing laser printer. However, even if the electronic components to be used are changed, for example, the software changes are insignificant. It is a thing. Therefore, the diversion of the processing of the laser printer to the serial printer can be basically realized by partially changing the modularized software as described above.

[Effects of the Invention] As is clear from the above description, the serial printer according to the present invention develops data received from the outside via the interface in the raster direction by the graphics processing unit and stores the data in the raster image buffer. At the same time, the print image stored in the raster image buffer is converted into a column image by a raster / column conversion unit and stored in the column image buffer.
The column image is supplied from the column image buffer to the print head in a format developed in the column direction to perform a serial printing operation. Therefore, the printer alone has a function as a so-called page printer, and a graphics processing unit which is the most important part of this kind of page printer and requires the most complicated program is newly developed separately. This makes it possible to use the graphics processing unit of the existing line printer as it is, and to provide a serial printer of stable quality with a minimum development period and development cost. In addition, since it can be shared with graphics processing in existing line printers, typeface information from font cartridges and the like used in existing line printers can also be used as is in this serial printer, improving its versatility. It has excellent effects, such as being able to perform.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ink jet serial printer according to an embodiment of the present invention, FIG. 2 is a block diagram of an existing laser printer, FIG. 3 is a flowchart of the serial printer shown in FIG. 5 is a diagram showing a raster / column conversion circuit, FIG. 5 is a schematic diagram showing a bit pattern of a raster image buffer, FIG. 6 is a correspondence diagram showing a relationship between a raster image buffer and a print image, and FIG. FIG. 3 is a schematic diagram illustrating a bit pattern of a buffer. In the figure, 11 is the control unit, 11c is the print image processing, 1
1d is a serial printer driver, 11e is raster / column conversion, 12 is a raster image buffer, 15 is a serial printer engine, 16 is a column image buffer, 31 to 38
Is a latch circuit, and 39 to 46 are multiplexers.

Claims (1)

(57) [Claims] An interface for receiving data from the outside in a serial printer that drives the print head while moving the print head relative to a print medium and performs pruning for each line, and receiving data via the interface. A graphics processing unit that develops a print image in the raster direction according to the data that has been processed, and a print image that is developed in the raster direction by the graphics processing unit is stored in a bitmap format, and writing and reading are performed in a raster system. A raster image buffer, a column image buffer for storing print data so that the print data can be supplied to the print head in a format developed in the column direction, and a print image stored in the raster image buffer converted to a column image. A raster / column conversion unit for storing the column image stored in the column image buffer by the raster / column conversion unit to the print head to perform a serial printing operation. A serial printer.