JP2004098313A - Printer with improved print data transfer efficiency - Google Patents

Abstract

A conventional packet size is fixed to a packet size determined at the time of initialization of D4 communication, and depending on the type of print data, overhead increases and printing efficiency decreases.
In a printer that receives print data from a host computer and prints, at the start of printing, in response to a first request from the host computer, the printer returns a transmission packet size of the print data and reduces the number of transmission packets. An interface task for returning a number of receivable transmission packets in response to a second request from the host computer requesting, and receiving print data of the returned number of transmission packets from the host computer; And a print task for processing the print data stored in the buffer and instructing a print engine to print, wherein the interface task is configured to execute the first request in response to the first request. The size of the transmitted packet returned in response to the Printer, characterized in that the variable control of the size corresponding to the free speed of the fan.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a printer with improved print data transfer efficiency.
[0002]
[Prior art]
After receiving the print data transmitted from the host computer, the printer temporarily stores the print data in a storage device called a buffer and outputs it to a medium such as paper or a file. Further, the printer transmits information such as a printing progress status, a paper jam, or an out of ink to the host computer as a printing status.
[0003]
For this purpose, the printer transmits and receives data to and from the host computer using the communication standard of IEEE1284.4. In this communication (hereinafter referred to as D4 communication), communication is performed by dividing channels according to data to be handled, such as print status and print data.
[0004]
The host computer and the printer divide the print data into packets in packet size units, and perform D4 communication. Conventionally, when a channel for handling print data is initialized, a packet size specified by a printer driver installed in a host computer is fixedly set as it is as a packet size. That is, the packet size set at the time of channel initialization has been applied to any print job.
[0005]
After the channel initialization, the following communication processing is performed to transfer the print data. That is, first, the host computer requests the number of packets that can be received at one time by the printer via the printer driver (credit request). In response, the interface task of the printer returns the number of receivable packets according to the free space in the reception buffer.
[0006]
If there is no free space in the reception buffer, the interface task of the printer returns zero credit (the number of packets is zero), and in response, the printer driver transmits a credit request again after a predetermined time has elapsed. When the number of receivable packets is returned from the printer, the host computer transmits the print data at once by the number of packets via the printer driver.
[0007]
In this print data transfer process, print data for the number of packets is continuously transmitted, and reception confirmation is not performed for each packet. When the transfer of the print data for one page is completed, the host computer performs a process of closing the channel. Then, as print data transfer processing for the next page, channel initialization is started, and the above-described communication processing is repeated for each page.
[0008]
[Problems to be solved by the invention]
However, conventionally, the packet size determined at the time of channel initialization is fixedly applied to any print job. Since the print processing speed of the printer is different depending on the data type of the print job such as text data or image data, there is also a difference in the reception buffer free speed.
[0009]
If the set packet size is too large for a print job with a low reception buffer free speed, there is a high probability that the host computer requests a credit and the printer returns zero credit before processing one packet. When zero credits occur, the overhead increases and the printing efficiency decreases.
[0010]
If the set packet size is too small for a print job with a high reception buffer free speed, a credit request and the number of responses to the request frequently occur, which causes an increase in overhead and similarly lowers printing efficiency.
[0011]
Therefore, even though the fixed packet size is optimal for print data of a certain print job, it is not optimal for print data of another print job, so that it is not possible to increase the printing efficiency. Was out. Therefore, an object of the present invention is to provide a printer with high printing efficiency by setting an optimal packet size for each print job.
[0012]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a printer which receives print data from a host computer and prints the print data in response to a first request from the host computer at the start of printing. In response to a second request from the host computer requesting the number of transmission packets, the number of receivable transmission packets is returned, and print data of the returned transmission packet number is transmitted from the host computer. An interface task for receiving, a buffer for temporarily storing print data transmitted from the host, and a print task for processing print data stored in the buffer and instructing a print engine to print, The interface task is currently processing a transmission packet size to be returned in response to the first request. It is accomplished by providing a printer, characterized by variably controlling the size corresponding to the free speed of the buffer for the print job.
[0013]
According to the first aspect, the packet size can be changed for each print job, and by setting an optimized packet size, overhead in print data transmission performed between the host computer and the printer is reduced, and printing efficiency is increased. It becomes possible.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited by such embodiments, but extends to the inventions described in the claims and their equivalents.
[0015]
FIG. 1 is a diagram illustrating a configuration example according to an embodiment of the present invention. The host computer 10 and the printer 20 perform D4 communication in order to transmit and receive data such as print data and print status. In D4 communication, communication is performed by dividing a channel for each data to be handled, and when the channel is initialized, the host computer 10 and the printer 20 determine a packet size to be used for subsequent communication.
[0016]
Then, the host computer 10 divides the print data and the like into a plurality of packets for each determined packet size, and transmits the packets to the printer 20. The transmitted packet is received by the interface task 22 that controls communication with the outside. The interface task 22 stores the received packet in the reception buffer 23.
[0017]
The print task 24 reconstructs data before division from the packets stored in the reception buffer 23. The print task 24 converts the received print data into printable data and supplies the print data to the print engine 25 in order to print the reconstructed print data by the print engine 25.
[0018]
The conversion to printable data means, for example, expanding the data into data corresponding to driving of nozzles of each color provided in an ink head of a print engine. After converting the print data into printable data, the print task 24 transmits the converted data and a print engine control command to the print engine 25.
[0019]
The print engine 25 has, for example, an ink head and a paper supply / discharge mechanism, and performs printing on a medium such as paper according to a control command from the print task 24. Since data is read from the reception buffer 23 by the processing of the print task 24, an empty area is created in the reception buffer 23. If there is a free space in the reception buffer 23, the host computer 10 sequentially performs the data transfer processing until the transfer of the remaining print data is completed.
[0020]
The interface task 22 and the print task 24 are functionally implemented by the CPU 21 executing an application program stored in the memory 26, but may be implemented as hardware.
[0021]
FIG. 2 is a diagram schematically illustrating an example of the inside of the reception buffer 23. One block when the reception buffer is divided for each packet size is called a credit 27.
[0022]
The size of one credit is equal to the packet size, and the number of credits and the number of packets correspond one to one. That is, the number of packets equal to the number of available credits can be received. In FIG. 2, a credit buffer of 128 kilobytes includes 8 credits with a packet size of 16 kilobytes.
[0023]
3 and 4 are diagrams for explaining the data transfer processing according to the present invention. This is an example in which the packet size can be changed for each page by performing a packet size determination process described later with reference to FIG. 5 for each page.
[0024]
In FIG. 3, first, the host computer 10 transmits an open request command to initialize a channel used for page data transfer (S301). As an argument of the command, the host computer 10 specifies the packet size as 65,535 bytes. This is the maximum number that can be represented in the packet size field described in FIG.
[0025]
The printer 20 performs a packet size determination process described later to determine a packet size (S302). In FIG. 3, it is assumed that the size is determined to be 16 kilobytes. Then, the printer 20 transmits an open channel reply command to the host computer 10 as a response to the open channel request command transmitted in step S301 (S303).
[0026]
In FIG. 3, the 16 kilobytes determined in step S302 are returned to the host computer 10. Through steps S301, S302, and S303, the packet size used in the subsequent page data transfer processing is determined to be 16 kilobytes.
[0027]
Next, the host computer 10 requests the number of receivable packets in the reception buffer to transfer the print data (S304). The printer 20 responds with the number of available credits in the reception buffer 23 as the number of receivable packets (S305). Here, the vacancy of 6 credits is notified.
[0028]
The host computer 10 transmits data in accordance with the number of credits returned in step S305 (S306). The host computer 10 transmits six packets to the printer 20.
[0029]
The host computer 10 completes the transmission of the page data, transmits a close channel request command, and ends the use of the channel (S307). The printer 20 transmits a close channel reply command to the host computer 10 as a response to the close channel request (S308). At this point, the page data transfer process ends once.
[0030]
Subsequently, if there is more page data, the data transfer processing of the next page is started.
The host computer 10 transmits an open request command and initializes a channel used for page data transfer (S309). As an argument of the command, the host computer 10 specifies the packet size as 65,535 bytes.
[0031]
The printer 20 performs a packet size determination process described later to determine a packet size (S310). In FIG. 3, it is assumed that the size is determined to be 20 kilobytes. Then, the printer 20 transmits an open channel reply command to the host computer 10 as a response to the open channel request command transmitted in step S309 (S311).
[0032]
In FIG. 3, the 20 kilobytes determined in step S310 are returned to the host computer 10. In steps S309, S310, and S311, the packet size used in the subsequent page data transfer processing is determined to be 20 kilobytes. Next, the host computer 10 requests the number of receivable packets in the reception buffer to transfer the print data (S312).
[0033]
Referring to FIG. 4, the printer 20 responds with the number of available credits in the reception buffer 23 as the number of receivable packets (S313). In FIG. 4, the vacancy of 4 credits is notified. The host computer 10 transmits data in accordance with the number of credits returned in step S313 (S314). The host computer 10 transmits four packets to the printer 20.
[0034]
Thereafter, steps S312 to S314 are repeated until the transfer of the page data is completed, and when the transfer of the page data is completed, the use of the channel is stopped by the close channel request and the close channel reply command as in steps S307 and S308.
[0035]
The data transfer processing of FIGS. 3 and 4 makes it possible to change the packet size for each page, and by setting an optimal packet size, it is possible to reduce overhead and increase printing efficiency. Since the packet size is changed for each page, the packet size is changed for each print job. Next, how to determine the optimum packet size will be described.
[0036]
FIG. 5 is a flowchart illustrating the packet size determination processing. The reception buffer free speed varies depending on the type of print data of the print job. If the packet size is made larger than the current setting for a print job with a high reception buffer free speed, the number of credit requests and the number of responses are reduced, and printing efficiency can be improved. Also, if the packet size is smaller than the current setting for a print job with a low reception buffer free speed, the overhead due to zero credits is reduced, and the printing efficiency can be improved.
[0037]
Therefore, in this packet size determination process, the receiving buffer free speed when printing the page data of the print job is determined based on the reference value set in accordance with the packet size. Increase the size. If the speed is slower than the reference value, the packet size is set smaller, and the packet size is set optimally for each print job.
[0038]
First, the printer 20 determines whether the page to be printed is the first page (S501), and if the first page of the print job is to be printed, sets the packet size to a default value (S502). The default value is a preset initial value, for example, 16 kilobytes.
[0039]
If the printer 20 is to print the second and subsequent pages of the print job, the printer 20 obtains the buffer free speed at the time of printing the previous page (S503). The buffer free speed is calculated by the print task 24 from the time from when page data is received until one page of data is read from the reception buffer, and the page data size. It is also possible for the print task 24 to determine the free speed of the buffer from the time from the reception of the page data to the end of the printing and the page data size.
[0040]
The printer 20 refers to a time table to be described later and obtains a buffer free speed reference value corresponding to the current packet size (S504). The time table describes a buffer empty speed reference value corresponding to the packet size. The time table is recorded in a ROM (Read Only Memory) not shown at the time of shipment, and is loaded into the memory 26 when the power of the printer 20 is turned on.
[0041]
Subsequently, the printer 20 determines whether the buffer empty speed measured in step S503 is faster than the buffer empty speed reference value in step S504 (S505). This is performed by the CPU 21 comparing the buffer empty speed reference value loaded in the memory 26 with the measured buffer empty speed of the print task 24.
[0042]
If it is determined in step S505 that the speed is fast, a packet size larger than the current packet size is set (S506). If it is determined in step S505 that the packet is late, a packet size smaller than the current packet size is set (S507).
[0043]
The amount of increase or decrease in packet size that occurs in step S506 or S507 is recorded in the time table as the amount of increase or decrease in packet size, and is, for example, 4 kilobytes. Then, page data is printed based on the packet size determined in step S502, S506, or S507 (S508).
[0044]
After changing the packet size a predetermined number of times in accordance with steps S501 to S508 (S509), the packet size used in the print job is finally determined (S510). For example, the packet size set last is selected and fixed as the packet size for the remaining page data of the print job.
[0045]
If the predetermined number is not reached in step S509, steps S501 to S508 are performed to determine the packet size for new page data. In FIG. 5, after changing the packet size a predetermined number of times, the final packet size is fixed, and the same packet size is used for the remaining pages of the print job. It is also possible to change each time.
[0046]
According to the packet size determination process of FIG. 5, in the case of a print job having a high reception buffer free speed, by setting the packet size larger than the current value, the overhead due to the credit request and the number of responses can be reduced, and the printing efficiency is improved. It is possible. Further, in the case of a print job having a low reception buffer free speed, by setting the packet size smaller than the current numerical value, the overhead due to zero credit can be reduced, and the printing efficiency can be improved.
[0047]
FIG. 6 is a diagram illustrating an example of the time table. For each packet size 601 (kilobytes), the correspondence between the buffer free speed reference value 602 (kilobytes per second) and the packet size variation 603 (kilobytes) is recorded. As the packet size 601 increases, the buffer empty speed reference value also increases.
[0048]
For example, when the packet size 601 is Y1 kilobytes, if the buffer empty speed reference value 602 is Y2 kilobytes per second and the measured buffer empty speed is Y2 kilobytes or more, the packet size is increased by X1 kilobytes from the present. On the other hand, if it falls below, it is reduced by X1 kilobytes.
[0049]
FIG. 7 is a diagram illustrating the packet size field. FIG. 7 illustrates a packet 71 used in the D4 communication. The packet 71 is divided into a plurality of fields used for a certain purpose. In that, two bytes of a packet size field 72 for determining the packet size are secured. The value that can be specified in the packet size field 72 is 0 to 65,535 bytes. FIG. 7 shows an example in which the packet size is set to 16 kilobytes.
[0050]
In the present invention, in order to stabilize data communication, the interface task 22 allocates resources such as a CPU with a higher priority than a print task 24 or the like which performs data conversion processing in a printer. Occupy. This is because if the priority of the interface task 22 is lower than that of the print task 24 or the like, even if the host computer 10 and the interface task 22 are performing data communication, an interrupt process by another higher priority task occurs, Communication is interrupted. Then, the data communication is restarted from the beginning, and the resources are further consumed by the host computer 10 and the printer 20, and the printing efficiency is deteriorated.
[0051]
Therefore, by increasing the transfer efficiency of the print data by the interface task 22 having the higher priority, the processing time of the print task 24 for performing the data conversion process is increased, and the print processing efficiency can be further increased.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration according to an embodiment; FIG. 2 is a diagram illustrating an example schematically illustrating the inside of a reception buffer; FIG. 3 is a diagram illustrating a data transfer process according to the present invention; FIG. 5 is a diagram illustrating a data transfer process according to the present invention. FIG. 5 is a flowchart illustrating a packet size determination process. FIG. 6 is a diagram illustrating an example of a time table. FIG. 7 is a diagram illustrating a packet size field.
10 host computer, 20 printer, 21 CPU,
22 interface tasks, 23 buffers, 24 print tasks,
25 print engines, 26 memory, 27 credits

Claims (4)

In a printer that receives print data from a host computer and prints,
At the start of printing, a transmission packet size of the print data is returned in response to a first request from the host computer, and reception is possible in response to a second request from the host computer requesting the number of transmission packets. An interface task for returning the number of transmitted packets, and receiving print data of the returned number of transmitted packets from the host computer;
A buffer for temporarily storing print data transmitted from the host,
A print task for processing print data stored in the buffer and instructing a print engine to print,
The printer according to claim 1, wherein the interface task variably controls a transmission packet size returned in response to the first request to a size corresponding to an available speed of the buffer for a print job currently being processed. In claim 1,
The interface task controls the transmission packet size to a first size when the empty speed of the buffer is the first speed, and controls the transmission packet size at a second speed where the empty speed of the buffer is faster than the first speed. A printer, wherein the size of the transmission packet is sometimes controlled to a second size larger than the first size. In claim 2,
The printer according to claim 1, wherein the interface task monitors an available speed of the buffer for the print job, and sets the transmission packet size for each page break. In claim 1,
The printer according to claim 1, wherein the interface task is executed with a higher priority than the print task.

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