JP2002137457A - Printer and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the print speed when a printer comprises a small capacity buffer which can store a line of print data. SOLUTION: Swath data (a line of print data) is written from the head address of a buffer 4 and a write pointer is shifted sequentially (Figs. (a) and (b)). After writing is completed, the write pointer is shifted to the head address of the buffer 4 by a print start command and, at the same time, delivery of the swath data is started and a read pointer is shifted sequentially ((c)). When a write command is received in the way of delivery of the swath data and a decision is made that the empty capacity from the head of the buffer 4 has reached 835 bytes, writing of next swath data from the head address of the buffer 4 is started ((d)) in parallel with delivery of previous swath data and the read pointer is shifted forcibly to the final address simultaneously with the end of delivery of previous swath data ((e) and (f)).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a buffer having a capacity capable of storing one line of print data transmitted from a host computer. The present invention relates to a printing apparatus which sequentially prints out print data of a minute from a head address of a buffer and prints the print data, and a control method thereof.

[0002]

2. Description of the Related Art Generally, in a printer as a printing device,
The print data transmitted from the host computer is stored in a buffer. In order to reduce the buffer capacity as much as possible and reduce the cost, one line of print data (hereinafter referred to as this one line) is used as a buffer. A memory having a capacity small enough to store print data (referred to as "swath data") is used.

Then, the swath data from the host computer is temporarily stored in a swath buffer having a capacity capable of storing such swath data, and after the storage is completed, the swath data is sequentially discharged from the head address of the swath buffer and printed on a predetermined sheet. ing.

In this case, when the printing of one line of printing data is completed, the printing data of the next one line is written into the swath buffer. ) To (d). However, FIG.
In the above, ▽ represents a write pointer indicating to which address of the buffer the swath data has been written, and ▼ represents a read pointer indicating to which address of the buffer the swath data has been discharged.

Now, as shown in FIG. 3A, in a state where nothing is written in the buffer B, FIG.
As shown in (1), when swath data (hatched portion) is sequentially written in the direction of the solid arrow from the head of the buffer B, the write pointer ▽ sequentially moves with the writing.

Subsequently, when the writing of the swath data is completed, the swath data is discharged in accordance with the print start command, as shown by the broken arrow in FIG.
The read pointer ▼ sequentially moves with the ejection.

When the next swath data write command comes in the middle of swath data ejection,
Since the position of the write pointer 表 わ す indicating the end address of the previous swath data being ejected is recognized as the head when writing the next swath data, and the position after the write pointer ▽ is determined to be an empty portion of the buffer B, FIG. As shown in FIG. 3 (c), the writing of the next swath data is started following the last position of the swath data that has been discharged earlier.

When the next swath data being written cannot be completely written by the actual final address of the buffer B, the writing continues from the actual start address of the buffer B as shown in FIG. Is performed.

[0009]

However, in a printer using such a small-capacity buffer, writing of the next swath data starts from the last position of the previous swath data, and returns to the head address of the buffer B to perform writing. If the writing is continued, it is necessary to return the write pointer to the first address when the next swath data write reaches the last address of the buffer B. At this time, whether the position of the write pointer is the last address of the buffer B is determined. And the control of returning the position of the write pointer to the head address of the buffer B must be performed.
There is a problem that the control is complicated and the printing speed is reduced.

In order to improve the printing speed in a printing apparatus such as a printer, Japanese Patent Application Laid-Open No.
10622, JP-A-10-275067, JP-A-11-99709, JP-A-2000-1
There are inventions described in Japanese Patent No. 72456, but all of these inventions are related to control when the buffer has a relatively large capacity of several lines or one page.
It does not relate to read / write control of a buffer having a capacity capable of storing one line of print data as in the present invention, but applies the technology described in each of the above publications to read / write control of a small-capacity buffer as in the present application. It cannot be applied as it is, nor can it be expected a significant technical effect.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the printing speed when a buffer having a small capacity enough to store one line of print data is provided.

[0012]

To achieve the above object, a printing apparatus according to the present invention includes a buffer having a capacity large enough to store one line of print data transmitted from a host computer. After the storage of the one line of print data in the buffer is completed, the one line of print data is sequentially discharged from the head address of the buffer and printed. A write pointer indicating to which address the data has been written, a read pointer indicating to which address of the buffer the print data for the one line has been discharged, and a head of the buffer by the discharge after the start of the discharge of the print data. It is determined whether or not the free space of the portion has reached a predetermined amount, and if it has reached the predetermined amount, the buffer A read / write control unit for continuously writing the next one line of print data from the start address in parallel with the ejection of the preceding one line of print data; and a read / write control unit for reading the one line of print data by the read / write control unit. A movement control unit that moves the read pointer and the write pointer to a head address of the buffer at the start of ejection and moves the read pointer to an end address of the buffer at the time of ejection completion.

According to such a configuration, the ejection of the print data for the previous one line and the writing of the print data for the next one line are performed in parallel, and the ejection of the print data for one line is performed. At the start, the read pointer and the write pointer are moved to the head address of the buffer, and when the ejection is completed, the read pointer is moved to the end address of the buffer.

Therefore, the writing of the next one line of print data can always be started from the head address of the buffer, and the print data of one line extends from the last address of the buffer to the head address as in the related art. And the need to determine whether the end address of the buffer has been reached and return to the start address is no longer necessary, which can simplify the process and improve the overall printing speed. can do.

Further, the printing apparatus according to the present invention includes an interface conforming to the USB standard connected to the host computer, and the predetermined amount is at least 835.
It is characterized by being set to bytes.

According to such a configuration, even when print data is transmitted from the host computer according to the protocol of the USB standard, after the discharge of the previous one line of print data is started, the head of the buffer by the discharge is started. When the free space of the portion reaches 835 bytes, the next one line of print data is continuously written from the head address of the buffer, so that the discharge of the previous one line of print data and the next one line
The writing of the print data for the lines can be performed in parallel, and the printing speed can be improved.

The printing apparatus according to the present invention includes a parallel interface connected to the host computer, wherein the predetermined amount is set to at least one byte.

According to such a configuration, even when the print data is transmitted in parallel from the host computer, after the start of the ejection of the previous one line of the print data, the free space at the head of the buffer by the ejection is obtained. Reaches 1 byte, the next one line of print data is continuously written from the head address of the buffer, so that the previous one line of print data is discharged and the next one line of print data is written. Can be performed in parallel, and the printing speed can be improved.

Preferably, the printing apparatus according to the present invention further comprises a decompression unit for receiving and decompressing the print data transmitted from the host computer through the interface after being compressed.

According to this configuration, since the print data compressed by the decompression unit is decompressed, the load on the read / write control unit is reduced, and the processing speed of the read / write control unit is not reduced. The printing speed can be improved.

Further, in the control method of the printing apparatus according to the present invention, after the start of the ejection of the print data, it is determined whether or not the free space at the head of the buffer by the ejection has reached a predetermined amount. If the predetermined amount has been reached, the next one line of print data is continuously written from the head address of the buffer in parallel with the ejection of the previous one line of print data. A read pointer indicating to which address of the buffer the print data for one line has been discharged at the start of discharge
And moving a write pointer indicating to which address of the buffer the print data for one line has been written to the head address of the buffer, and changing the read pointer when the ejection of the print data for one line is completed. It is characterized by moving to the end address of the buffer.

According to such a configuration, the writing of the next one line of print data can always be started from the head address of the buffer, and the print data of one line is stored at the end of the buffer as in the conventional case. It is possible to prevent writing from the address to the start address, and it is not necessary to determine whether the end address of the buffer has been reached and to return to the start address, thereby simplifying processing. The speed in the entire printing can be improved.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an ink jet printer as a printing device will be described with reference to FIGS. 1 is a block diagram, and FIG. 2 is an operation explanatory diagram.

In the ink jet printer according to the present embodiment, as shown in FIG. 1, a personal computer (hereinafter referred to as a personal computer) 1 as a host computer.
Command data and print data sent from
Received by the SIC2 and temporarily stored in a register or the like,
While the command data is analyzed by the CPU 3, the print data is sequentially written to the swath buffer 4 by the CPU 3.

At this time, the personal computer 1 and the ASIC 2
For example, they are connected by a connector and a cable (both not shown) conforming to the USB standard. The buffer 4 is formed of a memory having a small capacity enough to store one line of print data.

Print data is sequentially discharged from the swath buffer 4 in response to a print start command from the personal computer 1, and a carrier motor driver (not shown in FIG. 1) for driving a carrier motor and a paper feed motor are provided. The feed motor driver to be driven is controlled by the CPU 3 so that characters, figures, and the like based on print data are printed on paper.

When the CPU 3 controls the writing and discharging of print data to and from the buffer 4, the following is performed. That is, the CPU 3 sequentially writes one line of print data (swath data) in the buffer 4 from the head address in accordance with the write command, starts discharging the swath data from the buffer 4 in accordance with the print start command, and thereafter starts the head of the buffer 4 by discharging. It is determined whether or not the free space of the portion has reached a predetermined predetermined amount of 835 bytes. If the free space has reached 835 bytes, the next swath data is written continuously from the head address of the buffer 4. , In parallel with the discharge of the previous swath data. The processing of writing and discharging print data by the CPU 3 corresponds to a read / write control unit.

The criterion for determining the free space of the buffer 4 is 8
The reason why 35 bytes is used is that, in the case of USB, print data is transmitted in a packet. Therefore, when writing the next one line of print data, if at least 835 bytes of free space is secured, transmission in a packet is performed. This is because the received print data can be written.

At the start of swath data discharge, the CPU 3 stores a read pointer indicating to which address of the buffer 4 the swath data has been discharged and a write pointer indicating to which address of the buffer 4 the swath data has been written. 4 and forcibly moves the read pointer to the end address of the buffer when the swath data ejection is completed. The movement processing of each pointer by the CPU 3 corresponds to a movement control unit.

More specifically, the operation of writing and discharging print data will be described step by step.
As shown in FIG. 2A, in a state in which nothing is written in the buffer 4, as shown in FIG. When data is sequentially written in the direction of the solid arrow, the write pointer ▽ is sequentially moved with the writing.

Next, when the swath data writing is completed and a print start command is received, the CPU 3 forcibly returns the write pointer # to the head address of the buffer 4 and then returns to the broken line in FIG. As indicated by an arrow, swath data discharge is started, and the read pointer ▼ is sequentially moved with the discharge.

When a write command for writing the next swath data is received during the discharge of the swath data, the CPU 3 determines the amount of free space from the beginning of the buffer 4 accompanying the discharge of the previous swath data. When the free space reaches 835 bytes, writing of the next swath data (hatched portion inclined rightward) is started from the head address of the buffer 4 indicated by the write pointer ▽, as indicated by the solid arrow in FIG. The discharge of the previous swath data and the writing of the next swath data are executed in parallel.

Further, as shown in FIG. 2 (e), when the discharge of the previous swath data is completed, the read pointer ▼ is forcibly moved to the last address of the buffer 4 by the CPU 3, and when the next swath data is long, it will be continued thereafter. The writing of the next swath data is continued. When the writing of the next swath data is completed, the process waits for a print start command for printing the swath data that has been written.

Thereafter, when a print start command is received, C
The PU3 changes the write pointer に at the end address of the swath data and the read pointer ▼ at the last address of the buffer 4 into the buffer 4 as shown in FIG.
Is forcibly moved to the first address, and thereafter the above-described operation is repeatedly performed. In this manner, the print data of a plurality of lines is written into the buffer 4 and discharged, and printing is performed.

As described above, the discharge of the previous swath data (print data for one line) and the writing of the next swath data are performed in parallel, and the read pointer ▼ and the write pointer ▽ are buffered at the start of the discharge of the swath data. 4 and the read pointer ▼ is moved to the end address of the buffer 4 when the ejection is completed.

Therefore, according to the above-described embodiment, the writing of the next swath data can always be started from the head address of the buffer 4, and the swath data extends from the last address of the buffer 4 to the head address as in the related art. Thus, it is not necessary to determine whether or not the last address of the buffer 4 has been reached and return to the first address.
Can be simplified, and the overall printing speed can be improved.

Also, even when swath data is transmitted from the personal computer 1 according to the USB standard protocol, the free space at the head of the buffer 4 associated with the discharge reaches 835 bytes after the start of the discharge of the previous swath data. At this time, the writing of the next swath data is started from the head address of the buffer 4, so that the discharge of the previous swath data and the writing of the next swath data can be performed in parallel.

The ASIC 2 as a decompressing unit
The compressed data transmitted by the USB standard protocol may be decompressed. In this case, the load on the CPU 3 can be reduced, and the processing speed of the CPU 3 can be improved, which can further contribute to the improvement of the printing speed.

In the above embodiment, the personal computer 1
Although the case where the printer and the printer are connected by the USB interface has been described, it is a matter of course that the personal computer 1 and the printer may be connected by a parallel interface such as IEEE1284 which is a Centronics standard. At this time, the free space from the start address of the buffer 4 serving as a reference for determining whether to write the next swath data should be set to at least 1 byte.

Further, when the connection is established by the parallel interface, it is desirable that the ASIC 2 decompresses the swath data transmitted from the personal computer 1 via the parallel interface after being compressed and transmitted as the decompression unit. Also, by decompressing data by the ASIC 2, the load on the CPU 3 can be reduced, and the printing speed can be improved without lowering the processing speed of the CPU 3.

In the above-described embodiment, the case where the printing device is an ink jet printer has been described. However, the printing device is not limited to the ink jet printer, and in short, has a small capacity enough to store one line of print data. The present invention can be applied to any device provided with the buffer described above, and an effect equivalent to that of the above-described embodiment can be obtained.

Further, the host computer is not limited to the personal computer 1 as described above.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the gist of the present invention.

[0044]

As described above, according to the first and fifth aspects of the present invention, writing of the next one line of print data can always be started from the head address of the buffer. In addition, since it is possible to prevent one line of print data from being written from the last address of the buffer to the first address, it is not necessary to determine whether the last address of the buffer has been reached and return to the first address. Accordingly, the processing can be simplified, and the speed of the entire printing can be improved. Therefore, the present invention is suitable for a printing apparatus having a buffer having a small capacity enough to store one line of print data.

According to the second aspect of the present invention, even when print data is transmitted from the host computer according to the protocol of the USB standard, after the discharge of the previous one line of print data is started, When the free space at the head of the buffer by the ejection reaches 835 bytes, the next one line of print data is continuously written from the head address of the buffer, so that the ejection of the previous one line of print data and the next Writing of print data for one line can be performed in parallel, and the printing speed can be improved.

According to the third aspect of the present invention, even when print data is transmitted in parallel from the host computer, after the discharge of the previous one line of print data is started, the buffer of the buffer by the discharge is started. When the free space at the beginning reaches one byte, the next one line of print data is continuously written from the beginning address of the buffer.
The ejection of the print data for the previous one line and the writing of the print data for the next line can be performed in parallel, and the printing speed can be improved.

According to the fourth aspect of the present invention, since the print data compressed by the decompression unit is decompressed, the load on the read / write control unit is reduced, and the processing speed of the read / write control unit is reduced. It is possible to improve the printing speed without inducing.

[Brief description of the drawings]

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

FIG. 2 is an operation explanatory diagram of one embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 personal computer (host computer) 2 ASIC (decompression unit) 3 CPU (read / write control unit, movement control unit) 4 swath buffer

Claims (5)

[Claims] 1. A buffer having a capacity large enough to store one line of print data transmitted from a host computer, and after storing the one line of print data in the buffer is completed. A printing apparatus for sequentially ejecting and printing print data from a head address of the buffer; a write pointer indicating to which address of the buffer the print data of the one line is written; and a print data of the one line. A read pointer indicating to which address of the buffer has been ejected, and after starting the ejection of the print data, it is determined whether or not the free space at the head of the buffer by ejection has reached a predetermined amount. If the fixed amount has been reached, writing of the next one line of print data is continuously performed from the head address of the buffer for the previous one line. A read / write control unit that performs processing in parallel with the ejection of print data, and when the read / write control unit starts ejection of the one line of print data, the read pointer and the write pointer are moved to the head address of the buffer, and ejection is completed. A movement control unit that sometimes moves the read pointer to the end address of the buffer. 2. A computer connected to the host computer.
2. The printing apparatus according to claim 1, further comprising an interface conforming to the SB standard, wherein the predetermined amount is set to at least 835 bytes. 3. The apparatus according to claim 1, further comprising a parallel interface connected to said host computer, wherein said predetermined amount is set to at least one byte.
3. The printing device according to claim 1. 4. The printing method according to claim 2, further comprising a decompression unit for receiving and decompressing print data transmitted from the host computer through the interface through data compression. apparatus. 5. A buffer having a capacity large enough to store one line of print data transmitted from the host computer, and after storing the one line of print data in the buffer, In the control method of a printing apparatus for sequentially discharging and printing print data from a head address of the buffer, after the start of the discharge of the print data, the free space of the head portion of the buffer by the discharge reaches a predetermined amount. If the predetermined amount has been reached, the next one line of print data is written continuously from the head address of the buffer in parallel with the ejection of the previous one line of print data. A read pointer indicating to which address of the buffer the print data for one line has been discharged at the start of discharge of the print data for one line; A write pointer indicating to which address of the buffer the print data of one line has been written is moved to a head address of the buffer, and when the ejection of the print data of one line is completed, the read pointer is shifted to the buffer. A control method for a printing apparatus, characterized by moving to an end address of the printer.