JP2001187468A - Printer and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the total waiting time by reducing the possibility of interrupting print operation due to running out of sheet in the way of print operation. SOLUTION: When a plurality of print jobs are subjected to command interpretation and stored in a storage section (S1: YES), a printable job is extracted from stored print jobs (S2). Sheet feed method, sheet discharge method, and carrying passage preset for each print job are checked for abnormality with reference to an engine state management table thus deciding whether the print job is printable or not. If a plurality of print jobs are printable (S4: YES), any one print job is selected based on the order of arrival or a priority set on the host computer side (S5). Since print operation can be carried out starting from a printable job, the possibility of interrupting print operation due to running out of sheet can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer and a printing method such as an ink jet printer and a laser printer, and more particularly to a printer and a printing method capable of storing a plurality of print requests.

[0002]

2. Description of the Related Art For example, when print data is input from a host computer such as a personal computer, a printer interprets a command of the print data and generates print image data. The generated print image data is input to the print engine and printed.

A user can make various print settings when instructing printing. The user can appropriately set, for example, a paper feeding method, a paper discharge destination, color / monochrome printing, double-sided printing / single-sided printing, the number of copies, and the like. The printer executes printing based on the designated print settings or initial values preset in the printer. As a result, the paper is taken out from the designated paper feed tray and transported toward the printing unit. The paper printed by the printing unit is discharged to a specified discharge tray.

An error process is performed when the paper feed tray is out of paper or when the paper discharge tray is full and cannot be discharged. That is, printing is interrupted, and the user is notified of the cause of the error. When the paper and toner are replenished and the printed paper is removed from the paper output tray and the error is recovered, the interrupted printing is resumed.

[0005]

Recently, LAN (Local)
With the development of a network environment such as an area network, a network printing system in which one or more printers are shared by a plurality of host computers has become widespread. A network-compatible printer may include a storage device such as an HDD (Hard Disk drive) for receiving print data (print job) from a plurality of host computers.

[0006] Normally, printing is performed by a first-in first-out method (FIFO). That is, printing is performed sequentially from the print job that arrives first. However, if the printer also supports interrupt printing, interrupt printing is performed first.
Further, when the priority can be set for each print job, printing can be performed according to the priority. Here, in the related art, it should be noted that in any case, the printing order is determined based on the priority set on the host computer side.

When an attempt is made to start printing of a print job selected in accordance with a host computer-side processing standard such as a first-in first-out method or interrupt printing, there is no paper in a specified paper feed tray or a specified paper discharge. If the tray is full and cannot be used, the print job is interrupted. Therefore, it is impossible to print another succeeding print job, and the overall print waiting time becomes long. That is, the print waiting time increases until the print job has a possibility of printing, and the usability decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to process a print request that can be printed, thereby reducing the overall print waiting time and improving the usability. An object of the present invention is to provide a printer and a printing method as described above.

[0009]

In order to solve the above-mentioned problems, in a printer and a printing method according to the present invention, a print request to be printed is selected based on a state of a printing unit.

That is, according to the first aspect of the present invention, in a printer that performs printing based on input print data,
Generate print image data based on the print data,
Image generation means for issuing a print request, storage means for storing the print request, printing means for performing printing based on the print request stored in the storage means, monitoring means for monitoring the state of the print means, And selecting means for selecting a printable print request from among the print requests stored in the storage means based on an input from the monitoring means, and causing the print means to input the print request. .

The print data is input from a host computer such as a personal computer and a digital camera. The print data is not limited to this, and may be input via a PC card or a memory medium. The “print request” holds information necessary for printing, and can be called a print request structure. Specifically, for example, a print request is generated for each page, and information such as a dot pattern data storage destination address of a character used in the page, the number of copies, information indicating a print mode such as double-sided printing, and information such as a print position. It is comprised including. The print request is
It may be configured in the form of an intermediate language specifying the storage destination address of the dot pattern data, or may be configured in the form of final image data.

The issued print request is stored in the storage means. An example of the storage means is an HDD device. The storage unit is not limited to this, and the storage unit may be configured from one or a plurality of memories. If a memory medium such as a PC card can be mounted, an empty area of the PC card or the like may be used. The selection means selects a print request that can be printed based on the state of the printing means monitored by the monitoring means, and causes the printing means to input the selected printing request. The printing unit performs printing by operating each mechanism such as a paper transport mechanism and a printing unit based on the input print request. As described above, since a print request that can be printed is selected based on the state of the printing unit, it is possible to reduce the possibility that the cause of paper shortage or the like occurs before printing and printing is interrupted as in the related art. be able to.

Here, the “printable print request” includes, for example, a print request in which no printing failure is detected. Examples of the “printing failure” include at least one of paper shortage in the paper feed tray, unusable paper discharge tray, and abnormal transport path. "Output tray unusable" means both when the output tray is full and no more paper can be discharged, and when the output tray cannot be used because it is used or reserved by another print job. Can be included.

When a plurality of print requests that can be printed are detected, one print request can be selected based on a predetermined selection criterion. For example, based on the print data reception time, it is possible to select a print request related to the previously received print data from the print requests that can be printed. Further, based on the environment switching cost, it is possible to select a print request related to print data having the minimum environment switching cost from the print requests that can be printed. Here, the “environment switching cost” means, for example, the time required to switch the printing environment. When printing a print request having a different paper feed path or paper discharge path from the time of the immediately preceding print, it takes time to switch the print environment. Therefore, by selecting a print request that minimizes the environment switching cost, the overall print speed can be improved. Note that various methods can be used for calculating the environment switching cost. It may be obtained from an environment switching cost calculation formula prepared in advance or from an environment switching cost calculation table prepared in advance. If there are a plurality of print requests having the same environment switching cost, the processing may be performed on a first-come, first-served basis.

Further, a print request can be selected based on the possibility of double-sided printing. That is, a print request related to print data that can be combined and printed on both sides may be selected from printable print requests. For example, a case where one duplex printing job A includes a front page a1 and a back page a2 and another duplex printing job B includes a front page b1 and a back page b2 will be described as an example. In the normal case, a1 →
After printing a2, b1 → b2 is printed. But,
In this case, there is a play time before the printed front page passes through the reverse feeding path and reaches the printing section again. Therefore, in combination double-sided printing, a1 → b1 is continuously printed,
A2 → b2 are printed on the reverse side of the reversed and re-fed paper, respectively. As a result, the play time can be reduced and the printing time as a whole can be reduced. The number of sheets that can be continuously printed is determined by the direction of the sheet, the sheet size, and the length of the transport path.

Which print request can be printed is determined based on an initial setting value preset in the print data. Here, it is also possible to extract and select a print request that enables printing by changing the initial setting value. For example, even when the discharge tray specified by the initial setting value cannot be used, printing can be performed by changing to another empty discharge tray. Further, when the special paper is out of paper, the print data designating the special paper cannot be printed, but can be printed by changing to the plain paper having the remaining paper. A configuration in which all of the initial setting values can be changed, or a configuration in which only some preset setting values can be changed may be used. When the initial set value is changed, it is preferable to notify the user of the change through a monitor screen of the host computer or the like.

The present invention can be expressed as a printing method or a recording medium. Recording media include, for example, floppy disks (FD) and compact disks (CD-ROM, CD-ROM).
R), a hard disk (HD), various kinds of recording media such as a memory, and the like. In addition, the present invention is not limited to this. For example, a communication medium can be used, such as remotely downloading a program via a communication line.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

1. First Embodiment A first embodiment of the present invention will be described with reference to FIGS. The host computer 1 is realized, for example, as a personal computer, a workstation, a digital camera, a portable information terminal, or the like. The host computer 1 has an interface (hereinafter referred to as “I /
F ”), and a print data generation unit 3. When printing, in addition to specifying data to be printed, the user can specify, for example, a paper feeding method, a paper discharging method, a printing mode (two-sided printing or one-sided printing), the number of prints, and a printing color (color printing or monochrome printing). ) And various print settings such as priority (emergency printing or normal printing).

Note that the above-described print settings are merely examples, and it is not necessary to perform all the above-described settings. The print data generated by the print data generation unit 3 is transmitted from the I / F 2 to the communication line CN.
Is transmitted to the printer 11 via the. The communication line CN is
For example, it can be realized as a tangible transmission medium such as a serial connection cable, a parallel connection cable, or the like, and can also be realized as a spatial transmission medium such as infrared light or wireless communication.

The printer 11 includes an I / F 12, an input buffer 13, an image generation unit 14, a storage unit 15, a print request management unit 16, an output buffer 17, and a job management table 1.
8. Engine state management table 19, engine control unit 2
0 and a print engine 21.

The print data received from the communication line CN via the I / F 12 is temporarily stored in the input buffer 13. The image generation unit 14 as an “image generation unit” interprets a command of the print data to generate print image data, and issues a print request. The print request is
This information is generated for each page, and is, for example, information holding setting values such as font data used in the page, the number of copies, a print color, and a print mode. Each print request is stored in the storage unit 15 as a “storage unit”. The storage unit 15 is configured by a rewritable recording device such as an HDD device. The storage unit 15 stores a print request for each print job.

Print request management unit 16 as "selection means"
Is for selecting a print request to be printed next among the print requests stored in the storage unit 15. The print request management unit 16 extracts a print request that can be printed by referring to the job management table 18 and the engine state management table 19, and selects the next print request from the extracted print requests. It has become. The print request selected by the print request management unit 16 is image-developed on the output buffer 17 and input to the engine control unit 20. The engine control unit 20 executes predetermined printing by controlling the driving of the print engine 21 based on the print image data and the print setting value. The engine control unit 20 and the print engine 21 correspond to “printing means”.

Here, it should be noted that in the present embodiment, the data is stored in the storage unit 15 in the form of a print request. Since a print request is generated by interpreting print data, it is possible to grasp print settings such as a paper feeding method and a paper discharge tray before printing, and to determine in advance whether or not the print request is a printable print request.

FIG. 2 is an explanatory diagram showing an example of the engine state management table 19 which constitutes "monitoring means" together with various sensors provided in the print engine 21. The engine status management table 19 includes, for example, a plurality of tables of (a) a discharge tray status management table, (b) a paper feed tray status management table, (c) a transport path status management table, and (d) a color material management table. Can be configured.
However, the present invention is not limited to this, and the state of each paper discharge tray, the state of each paper feed tray, the state of each transport path, the state of each color material, and the like can be expressed as one table. As for the state of the paper discharge tray, it is monitored whether or not each paper discharge tray has an empty space. As the state of the paper feed tray, it is monitored which size paper is present in each paper feed tray. As the status of the transport route, whether or not each transport route is normal is monitored. For example, a path that has caused a paper jam or the like is detected as abnormal. As the state of the color material, it is monitored whether or not there is a remaining amount of the color material of each color (for example, toner in a laser printer and ink in an ink jet printer). Note that the remaining amount of paper, the free space of discharged paper, the remaining amount of coloring material, and the like may be monitored more finely, instead of monitoring whether or not there is. For example, the remaining amount of paper and the available empty space may be detected as a quantity.

FIG. 3 is an explanatory diagram showing an example of the print job management table 18. The print job management table 18 stores, for example, the storage unit 1 for each print request of each print job.
5, the storage destination address, print mode, print color, paper size, paper feed tray, paper discharge tray, priority, data reception time, and the like can be stored in association with each other. Note that among the parameters shown in FIG. 3, those described in the print request need not be described in the print job management table 18. It is enough to refer to the description contents of the print request. Note that the reference numbers of the print requests shown in the figure will be explained. J11 is a print request for the first page of print job 1, J12 is a print request for the second page of print job 1, and J21 is a first page of print job 2. Each shows a print request for an eye.

Next, the operation of the present embodiment will be described with reference to FIGS. First, FIG. 4 is a flowchart schematically showing an entire process of selecting and printing a print job to be processed next from a plurality of print jobs. In step (hereinafter abbreviated as “S”) 1, it is determined whether or not a plurality of print jobs are stored in the storage unit 15. If a plurality of print jobs are stored (S1: YES), a printable print job is extracted from the plurality of print jobs stored in the storage unit 15 (S2). This extraction processing is described in FIG.
It will be described later together.

It is determined whether a printable print job has been extracted (S3). If a printable print job has been extracted (S3: YES), a plurality of printable print jobs are extracted. It is determined whether or not it has been (S4). If there are a plurality of print jobs that can be printed (S4: YES), one of the print jobs is selected (S5). For example, the print job received earlier may be selected, or may be selected based on the priority set on the host computer 1 side. If there are not a plurality of print jobs that can be printed (S4: NO), steps S5 and S6 are skipped.

Then, print requests are taken out in order from the selected print job and printing is started (S7). During printing, it is monitored whether or not interrupt printing has occurred (S
8) If interrupt printing has occurred, current printing is temporarily interrupted and interrupt printing is performed (S9). It is also monitored whether an error has occurred during printing (S10). Even for a print job that has been determined to be printable and printing has started, there is a possibility of running out of paper or paper jam during printing. If an error occurs during printing (S10: YES),
Printing is interrupted (S11). Then, it is determined whether the printing of the job is completed (S12), and the process returns to S7 until the printing of the job is completed. When the printing of the print job is completed (S12: YES), the print request relating to the printed job is discarded from the storage 15 (S13).

Next, FIG. 5 is a flowchart showing an example of the extraction processing shown in S2 in FIG. First, 1 is set to a variable JN for sequentially specifying print jobs (S21). Then, the job management table 18 and the engine management table 19 are respectively referred to (S22,
S23). Then, for the first print job, it is determined whether there is an abnormality in paper feeding (S24), whether there is an abnormality in paper ejection (S25), and whether there is an abnormality in the transport path (S2).
6) It is determined whether or not the color material is abnormal (S27). If it is determined in each determination step that there is no abnormality, it is determined that the print job is printable (S28). Then, it is determined whether or not all the print jobs registered in the job management table 18 have been inspected (S29). If there is any uninspected print job (S29: NO), the variable JN is set to 1 only. The next print job is inspected with the number increased (S30). If all the print jobs have been checked for printability, the process ends.

FIG. 6 is an explanatory diagram schematically showing how the processing order of print jobs is changed according to the present embodiment. It is assumed that print data is received by the printer 11 in the order of job 1, job 2, job 3, and job 4.

As shown in FIG. 6A, job 1
The first and second pages are printed on A3 size paper, the third to sixth pages are printed on A4 size paper, and the last page is printed on A3 size paper. If the A3 size paper runs out immediately after printing the first page, printing of job 1 is interrupted. Therefore, FIG.
As shown in (b), the discharge tray # used by job 1
No. 1 remains in a state where the first page is discharged.

If processed on a first come, first served basis, job 2 would be printed next. However, if the discharge tray set for job 2 is # 2, job 2 cannot be printed. This is because the discharge tray # 2 is full of printed sheets that have been discharged before. Since the A3 size paper has run out, the next job 3 cannot be printed. If the output tray is not specified for job 4, or if any of the output trays # 3 or # 4 is specified, the job 4 that has arrived last is printed next. Become. Then, when A3 size paper is supplied, extraction and selection will be performed again, and printing of the interrupted job 1 will be resumed.

According to the present embodiment configured as described above, the following effects can be obtained.

First, a printable job is selected based on the state of the print engine 21 instead of determining the print job to be printed next in the order of priority or first-come-first-serve set on the host computer 1 side. Therefore, the possibility that printing is interrupted during printing can be reduced. As a result, the print waiting time as a whole can be reduced, and usability is improved. In other words, this embodiment is different from the related art in that the state of the print engine 21 is preferentially used as a criterion for selecting a job to be printed next.

Second, if there are a plurality of print jobs that can be printed, the user selects the job to be printed next based on the first-come-first-served order or the priority set on the host computer 1 side. Overall efficiency can be improved while reflecting hope.

2. Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. In the following embodiments, the same components as those of the above-described first embodiment will be denoted by the same reference numerals, and description thereof will be omitted. The feature of this embodiment is that, when a plurality of print jobs that can be printed are extracted, the print job with the lowest environment switching cost is selected.

FIG. 7 is a flowchart showing another example of the selection process shown in S5 in FIG. In the first embodiment, when there are a plurality of print jobs that can be printed, one of the print jobs is selected based on a first-come-first-served basis or a priority set on the host computer 1 side. . On the other hand, in the present embodiment, a new criterion called environment switching cost is introduced, and a print job with the minimum environment switching cost is selected.

First, it is determined whether or not a print job that can be printed in the current print environment exists in the print jobs extracted by the extraction process (S41). A job that can be printed in the current printing environment is a print job in which print settings such as a paper feeding method, a paper discharging method, and a conveyance path are considered to be the same or substantially the same as currently set values.

If there is no printable job in the current print environment (S41: NO), the print job received earlier is selected (S42). If there is a print job that can be printed in the current print environment (S41: YES),
It is further determined whether or not there are a plurality of them (S43). If there is only one print job with the minimum environment switching cost (S43: NO), this print job is selected (S4).
4). On the other hand, if there are multiple print jobs (S4
3: YES), select the print job received earlier (S
45).

With the present embodiment having the above-described structure, the same effects as those of the first embodiment can be obtained.
In addition, in the present embodiment, since the print job that minimizes the environment switching cost is selected, the switching time until the next print job is printed can be reduced, and the print waiting time can be reduced. Can be.

3. Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. A feature of the present embodiment is that a print job is selected to execute high-speed double-sided printing by combining a plurality of print jobs.

FIG. 8 is a flowchart of the selection process according to the present embodiment. If there are a plurality of printable jobs in the current print environment (S43: YES), it is determined whether the extracted print jobs include a pairable print job (S51). ). If there is a print job that can be paired (S51: YES), a high-speed double-sided printing sequence described later is realized by combining a plurality of print jobs (S52). On the other hand, if there is no print job that can be paired (S51: N
O), select the earliest print job from the print jobs with the minimum environment switching cost (S53).

FIG. 9 is an explanatory diagram schematically showing high-speed double-sided printing by pairing. As shown in FIG. 9A, two print jobs J1 and J2, each of which is printed on both sides,
Assume that J2 exists. If these print jobs are to be individually printed on both sides, the job J1 must be printed in the order of J11 → J12 → J13 → J14, and then the job J2 must be printed in the order of J21 → J22 → J23 → J24. FIG.
As shown in (b), the next printing cannot be performed until the one-side printed sheet returns to the position of the photosensitive drum again. Therefore, the time required for re-feeding the single-sided printed paper is wasted idle time.

Therefore, in this embodiment, the print job J
1 and J2, and as shown in the lower part of FIG. 9A, print requests related to the front side of the print requests included in the two jobs are collectively and continuously printed, and then the front side print is performed. The back side of the completed paper is continuously printed. Thereby, printing can be continued by effectively utilizing the time until the sheet related to J11 to be printed first is re-fed to the photosensitive drum. After completion of the duplex printing, each print job J1,
J2 is carried out to the designated paper discharge tray.

This embodiment employs different printing methods such that one side is continuously printed and the other side is continuously printed when a printed sheet is re-fed to a printing unit. The two-sided printing is executed by combining the print requests of the job. "

According to the present embodiment configured as described above, the same effect as in the first embodiment can be obtained.
In addition, in this embodiment, high-speed double-sided printing is performed by combining a plurality of print jobs, so that printing time can be reduced.

4. Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that the host computer 1
The point is that a print job that can be printed is extracted by changing the value of each print setting set by the printer 11 on the printer 11 side.

FIG. 10 is a flowchart of the extraction processing according to the present embodiment. If an abnormality is detected in any of the sheet feeding, sheet discharging, transport path, and color material, it is determined whether the set value can be changed (S61). Whether the setting value can be changed or not can be designated in advance by the user, for example. Specifically, for example, even when the user wants to print on the special paper, the printer 11 changes the paper feeding method by including information indicating that the user does not stick to the special paper in the print data. Will be able to. As for the paper discharge tray, if it is clear to which paper discharge tray the paper is discharged, it may not be necessary to discharge the paper to the first designated tray. If there is a setting item that can be changed (S61: YES), the first setting value is changed and the host computer 1 is notified (S62). Then, it is determined again whether or not printing is possible based on the new setting value. If there is no changeable setting item (S61: NO), the process proceeds to S29.

According to the present embodiment having such a configuration, the same effect as that of the first embodiment can be obtained.
In addition to this, in the present embodiment, the print setting value set on the host computer 1 side is appropriately changed on the printer 11 side to check printability, so that the print waiting time is further reduced. Can be.

In particular, in the case of a network printing system, the installation locations of the printer and the host computer are far from each other, and usually, users do not know each other's print settings. Therefore, each user may appropriately make print settings without any inevitable reason, such as because the uppermost discharge tray is most easily taken out. In such a case, since the printer can adjust the print settings between the users, the use efficiency of the printer can be improved as a whole, and the usability can be improved.

It should be noted that those skilled in the art can make various additions and changes within the scope of the present invention described in the above embodiments. For example, in each of the above-described embodiments, a configuration is described in which a print job that can be printed is first extracted, and then any one of the print jobs is selected. That is, a print job may be selected in a first-come-first-served order or in a priority order specified by the host computer 1, and whether or not the print job is printable may be checked.

Further, for example, in the second embodiment, the print job having the minimum environment switching cost is selected. However, the present invention is not limited to this, and there is no print job having the minimum environment switching cost. In this case, a print job with the next lowest environment switching cost may be selected.

It is also possible to configure so as to switch the print mode. For example, when there are a plurality of jobs for printing only one page, it is possible to print the two jobs together at one time. Specifically, when the maximum print size of the print engine 21 is A3, if two A4 sheets are arranged horizontally, printing can be performed at one time. So, A
If there are a plurality of print jobs of four sizes, two images may be formed on the photosensitive drum and printed simultaneously with one transfer.

Further, it is determined whether or not printing is possible by predicting the total amount of the color material used in each print request and comparing the predicted amount of the color material with the current remaining amount of the color material. Can also be configured.

[0056]

As described above, according to the printer and the printing method according to the present invention, a print request that can be printed is selected, so that the possibility that printing is interrupted during printing can be reduced. As a result, the printing waiting time can be reduced, and the usability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a printing system according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an engine state management table.

FIG. 3 is an explanatory diagram showing a job management table.

FIG. 4 is a flowchart illustrating a printing process.

FIG. 5 is a flowchart illustrating an extraction process.

FIG. 6 is an explanatory diagram showing how a print job is selected.

FIG. 7 is a flowchart illustrating a selection process according to the second embodiment of the present invention.

FIG. 8 is a flowchart illustrating a selection process according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing how to realize high-speed double-sided printing by combining different print jobs.

FIG. 10 is a flowchart illustrating an extraction process according to a fourth embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1 Host computer 3 Print data generation unit 11 Printer 14 Image generation unit 15 Storage unit 16 Print request management unit 18 Job management table 19 Engine status management table 20 Engine control unit 21 Print engine

Claims (15)

[Claims] 1. A printer that performs printing based on input print data, comprising: generating image data for printing based on the print data;
Image generation means for issuing a print request; storage means for storing the print request; printing means for performing printing based on the print request stored in the storage means; and monitoring means for monitoring the state of the print means. Selecting means for selecting a printable print request from among the print requests stored in the storage means based on an input from the monitoring means, and inputting the print request to the printing means. Printer. 2. The printer according to claim 1, wherein the selection unit selects a print request in which no print failure is detected as printable. 3. The printer according to claim 2, wherein the printing failure includes at least one of a paper shortage in a paper feed tray, an unusable discharge tray, and an abnormality in a transport path. 4. The printing apparatus according to claim 2, wherein, when there are a plurality of print requests that can be printed, the selection unit selects one print request based on a predetermined selection criterion. Printer. 5. The printer according to claim 4, wherein the predetermined selection criterion is a print data reception time, and a print request related to the print data received first is selected from printable print requests. 6. The printer according to claim 4, wherein the predetermined selection criterion is an environment switching cost, and a print request related to print data having a minimum environment switching cost is selected from printable print requests. . 7. The printing apparatus according to claim 4, wherein the predetermined selection criterion is a possibility of double-sided printing, and selects a print request related to print data that can be double-sided printed from among printable print requests. Printer. 8. The printing apparatus according to claim 1, wherein the selection unit is configured to select a print request that can be printed by changing an initial setting value set in the print data.
The printer according to any of the above. 9. The printer according to claim 8, wherein, when the initial setting value is changed, the selection unit notifies the user of the change. 10. A printing method for performing printing based on input print data, a step of issuing a print request based on print data, a step of storing the issued print request, and a step of storing the stored print request. A printing method comprising: a step of selecting a print request having no printing trouble among the requests; and a step of printing based on the selected print request. 11. A recording medium storing a computer program for controlling a printer, a function of generating print image data based on input print data and issuing a print request, and And a function of monitoring the state of the printing unit. Based on the state of the printing unit, select a printable print request among the stored print requests, and And a computer-readable recording medium storing a computer program for causing a computer to implement a selection function to be input to the computer. 12. The print function according to claim 11, wherein, when there are a plurality of print requests that can be printed, the selection function selects a print request related to the print data received first among the print requests that can be printed. Recording medium. 13. When there are a plurality of print requests that can be printed, the selection function selects a print request related to print data with a minimum environment switching cost from among the print requests that can be printed. 12. The recording medium according to item 11. 14. The printing apparatus according to claim 1, wherein, when there are a plurality of print requests that can be printed, the selection function selects a print request related to print data that can be combined and printed on both sides, among the print requests that can be printed. 12. The recording medium according to item 11. 15. The print function according to claim 11, wherein the selection function is configured to select a printable print request by changing an initial setting value set in the print data. Recording medium according to the above.