JP2010271547A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method, capable of reducing risk that toner supply to a developing device is not in time, even when toner is comparatively largely consumed at a time. <P>SOLUTION: A printing ratio distribution on a printing job performed at the last time is compared with a printing ratio distribution on a printing job performed at this point (S127). When it is determined that the printing ratio distribution is continued in a longitudinal direction, a page image shown by output data generated in S120 is forcibly rotated by only 180 degrees, so that the vertical direction of the page image is reversed with respect to that of the page image printed at the last time (S140). As a result, the newly printed page image is turned upside down with respect to the page image printed at the last time. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus and an image forming method for printing a print job, such as a copying machine, a printer, or a facsimile machine, having a function of forming an image on a transfer material. More specifically, the present invention relates to an image forming apparatus and an image forming method capable of stably forming high image quality by comparing print rate distributions for print jobs.

  In recent years, as the speed of image forming apparatuses has increased, a color image is formed in synchronization with the feeding of a transfer material using a plurality of photoconductors corresponding to the color of the toner, and on the transfer material. A tandem method that performs color superposition is attracting attention.

  In such an image forming apparatus, a two-component developer composed of a magnetic carrier and a toner is widely used as a developer used for developing an electrostatic latent image. The toner is charged by holding and mixing the two-component developer on the magnetic brush roll, and only the toner is uniformly formed into a thin layer on the developing roll, and a drum-shaped photoreceptor (hereinafter referred to as “photosensitive drum”). The electrostatic latent image formed on the surface is developed.

  In the developing device as described above, an agitation feed member such as a paddle for agitating the developer or a spiral for conveying the developer while agitating the developer is contained in a container for accommodating a two-component developer composed of a carrier and a toner. Is provided. With this configuration, uniform mixing of the toner and the carrier and frictional charging of the toner are sufficiently performed.

  In addition, the one-component contact developing device is also provided with a stirring sheet for conveying the developer while stirring the developer in a container for storing the toner, and a sponge roller for supplying the developer to the developer carrier. Uniform supply with toner and frictional charging of toner are sufficiently performed.

  By the way, at present, a compact image forming apparatus is desired. Therefore, a more compact developing device is also desired, and the capacity of the container for accommodating the developer is decreasing. When the capacity of such a container is reduced, it is necessary to frequently supply toner in order to compensate for toner consumption accompanying image output. In addition, the toner density fluctuation due to the toner supply in the container increases. Further, when outputting an image with a high printing rate, the amount of toner consumed for image output becomes extremely large, and there is a possibility that the toner supply may not be in time.

  A specific example in which the toner supply is not in time is shown in FIG. In the print job 500 printed last time in FIG. 8A, the printing rate distribution has a left-right bias, and the right side is a page image with a high printing rate. The print job 502 to be printed this time also has a left-right bias in the print rate distribution, and the right side is a page image with a high print rate. In this way, when the print rate distribution of the print job that was printed last time and the print job that is printed this time is continuous in the longitudinal direction, that is, the page image with the high print rate on the right side is continuous with the paper space in between. When printing, the following problems occur.

  That is, there is a high possibility that a relatively large amount of toner will be consumed at a time in the high printing rate portion of the page image 504 to be printed this time, and the toner supply to the developing device will not be in time, resulting in a decrease in image density and blurring of the image. Such as image defects occur.

  Also, the print job 600 printed last time in FIG. 8B has a vertical deviation in the print rate distribution, and in particular, the lower side is a page image with a high print rate. Further, the print job 602 to be printed this time has a vertical deviation in the printing rate distribution, and in particular, the upper side is a page image with a high printing rate. As described above, when the print rate distribution of the print job printed last time and the print job to be printed this time is continuous in the longitudinal direction, that is, the page image having a high print rate is continuously printed with the space between the papers. If the following problems occur:

  That is, a relatively large amount of toner is consumed at a high rate in the high printing rate portion of the page image 604 to be printed this time, and there is a high possibility that the toner supply to the developing device will not be in time. As a result, the image density is lowered and the image is blurred. Such as image defects occur.

  For this reason, in the past, there has been proposed a technique for extending the image formation time to ensure a constant toner density from the difference between the toner supply amount and the toner consumption amount (see, for example, Patent Document 1). In addition, there has been proposed an apparatus in which the time between sheets is increased to ensure the toner density in accordance with the increase in the printing rate of image data (see, for example, Patent Document 2).

JP 2005-1115050 A JP 2008-20696 A

  However, a motor that rotates a toner conveying member such as a spiral in order to detect the toner supply amount is used to extend the image formation time and secure a constant toner density from the difference between the toner supply amount and the toner consumption amount. It is necessary to measure the driving time of Therefore, it takes a long time to detect the toner supply amount, and there is a risk of reducing the number of images formed per unit time.

  In addition, when the image data having a high printing rate is continuously printed, the amount of toner supplied is very large if the time between sheets is increased and the toner density is secured in accordance with the increase in the printing rate of the image data. . For this reason, there is a fear that the number of images formed per unit time may be reduced by increasing the time between sheets.

  The present invention has been made in view of the above circumstances.

  An object of the present invention is to provide an image forming apparatus and an image forming method capable of reducing a possibility that the toner supply to the developing device may not be in time even when a relatively large amount of toner is consumed at one time.

  Another object of the present invention is to provide an image forming apparatus and an image forming method capable of stably forming a high-quality image without causing image defects such as a decrease in image density and blurring of the image.

The above object is achieved by the image forming apparatus and the image forming method according to the present invention. In summary, according to a first aspect of the present invention, there is provided a printing mechanism, and a control unit that takes in a print job sent from the outside and causes the printing mechanism to execute printing according to the printing job. In the image forming apparatus,
The control means includes
A printing rate analysis means for analyzing a printing rate distribution of a print job to be printed;
A printing rate storage means for storing a printing rate distribution of a previously printed print job;
A print rate comparison means for comparing a print rate distribution for a print job printed last time and a print rate distribution for a print job printed this time;
A top / bottom direction control means for controlling the page image obtained from the print job to be a top / bottom direction opposite to the top / bottom direction printed last time when the print ratio distribution unit determines that the print ratio distribution is continuous in the longitudinal direction; ,
An image forming apparatus is provided.

According to a second aspect of the present invention, in an image forming apparatus comprising: a printing mechanism; and a control unit that takes in a print job sent from outside and causes the printing mechanism to execute printing according to the printing job.
The printing mechanism is configured to be able to switch between the vertical direction and the horizontal direction while the paper direction of the output paper is the same size,
The control means includes
A printing rate analysis means for analyzing a printing rate distribution of a print job to be printed;
A printing rate storage means for storing a printing rate distribution of a previously printed print job;
A print rate comparison means for comparing a print rate distribution for a print job printed last time and a print rate distribution for a print job printed this time;
When the print rate comparison unit determines that the print rate distribution is continuous in the longitudinal direction, a paper direction switching control unit that switches the paper direction of the output paper for printing according to the print job to a direction opposite to the paper direction printed last time. When,
An image forming apparatus is provided.

According to the third aspect of the present invention, in the image forming method of taking a print job sent from the outside and causing the printing mechanism to execute printing according to the print job,
(A) analyzing the print rate distribution for the print job to be printed this time;
(B) comparing the print rate distribution for the previously printed print job with the print rate distribution for the print job printed this time;
(C) controlling to rotate the page image obtained from the print job by 180 degrees when it is determined in step (a) that the print rate distribution is continuous in the longitudinal direction;
An image forming method is provided.

According to a fourth aspect of the present invention, in the image forming method of taking a print job sent from the outside and causing the printing mechanism to execute printing according to the print job,
The printing mechanism is configured to be able to switch between the vertical direction and the horizontal direction while the paper direction of the output paper is the same size,
(A) analyzing the print rate distribution for the print job to be printed this time;
(B) comparing the print rate distribution for the previously printed print job with the print rate distribution for the print job printed this time;
(C) when it is determined in step (a) that the print rate distribution is continuous in the longitudinal direction, the step of switching the paper direction of the output paper for printing according to the print job to the opposite direction;
An image forming method is provided.

  According to the present invention, even when a relatively large amount of toner is consumed at a time, it is possible to reduce the possibility that the toner supply to the developing device will not be in time, and image defects such as a decrease in image density and blurring of the image occur. Therefore, a high quality image can be stably formed.

It is a block diagram which shows schematic structure of the network system to which 1st Example of this invention is applied. FIG. 6 is an explanatory diagram illustrating an example of a printer property dialog box DB. It is a flowchart which shows the print control routine described with the computer program of 1st Example comprised according to this invention. It is explanatory drawing which shows the mode of rotation of a page image. It is explanatory drawing which shows the paper feed cassette C1 of "A4" and the paper feed cassette C2 of "A4R" used in 2nd Example of this invention, respectively. FIG. 6 is an explanatory diagram schematically showing a paper feed switching configuration. It is a flowchart which shows the print control routine described with the computer program of 2nd Example comprised according to this invention. It is explanatory drawing which shows the formation aspect of the conventional page image.

  Hereinafter, an image forming apparatus and an image forming method according to the present invention will be described in more detail with reference to the drawings. The present invention also includes the following aspects.

  That is, the first aspect is an aspect as a computer-readable recording medium that records a computer program for causing a computer to realize the same function as the configuration according to the image forming method of the present invention.

  A 2nd aspect is an aspect as a program supply apparatus which supplies the computer program of a 1st aspect via a communication path. In the second aspect, the computer program is placed on a server or the like on a network, the necessary program is downloaded to the computer via a communication path, and this is executed, whereby the image forming apparatus and the image forming method of the present invention are executed. Can be realized.

Example 1
In order to further clarify the configuration and operation of the present invention, embodiments of the present invention will be described based on several examples. FIG. 1 is a block diagram showing a schematic configuration of a network system to which the first embodiment of the present invention is applied.

  As shown in FIG. 1, in the network system 10 to which the present embodiment is applied, a plurality of (two in the range displayed in FIG. 1) client computers (hereinafter simply referred to as “clients”) that generate a print job. ) 20,30. Further, the printer 40 includes one printer 40 that is an image forming apparatus that prints a print job. The clients 20 and 30 and the printer 40 are connected to each other via a computer network 50 constructed by a local area network (LAN).

  The computer network (hereinafter simply referred to as “network”) 50 can be replaced with various networks such as the Internet, an intranet, and a wide area network (WAN) instead of the LAN.

  Here, the print job is a set of data representing one printed matter, and is composed of image data, control data, and the like.

  The clients 20 and 30 are so-called personal computers having a CRT display, a keyboard, a mouse, and the like as peripheral devices. The client 20 constructs each functional block shown in the figure by software in order to realize a function for generating a print job. That is, an application 21 is stored in the client 20, and a user inputs data using the application 21, or creates data to be printed under the application using a resource in the client.

  Further, the client 20 includes a printer driver 22 that receives data from the application 21 and creates a print job for the printer. Furthermore, the client 20 is provided with a print queue 23 for storing data created by the printer driver 22 in the client until transmission is completed, and a communication control unit 24 for transmitting a print job to the network 50.

  The printer driver 22 includes an information setting unit (not shown) that sets various information for printing by the printer 40 therein. Various information for printing includes information related to basic printing settings such as print quality, color correction, and halftone type, and information related to paper settings such as paper size and printing direction. By this operation of the information setting unit, a printer property dialog box is displayed on the CRT display of the client 20, and a key input by the user from this dialog box is accepted. Thereby, the setting of various information related to printing by the printer can be input into the information setting unit.

  FIG. 2 is an explanatory diagram showing an example of a printer property dialog box DB. In this dialog box DB, five types of cards CD1, CD2, CD3, CD4, and CD5 of “information”, “detail”, “basic setting”, “paper setting”, and “utility” are prepared. The “information” card CD1 is for setting information about the printer such as a comment of the printer. The “detail” card CD2 is used for setting detailed information about the printer such as a port to which the printer is connected. The “basic setting” card CD3 is used to set basic information related to print quality. The “paper setting” card CD4 is used to set various information about paper. The “utility” card CD5 is used to set other useful information.

  FIG. 2 shows a state in which the “paper setting” card CD4 is opened. As shown in the drawing, the “paper setting” card CD4 has data input fields F1, F2, F3, F4 for setting “paper size”, “number of copies”, “printing direction”, and “printable area”, respectively. And a display field F5 showing a three-dimensional stereoscopic image of the printer 40 as a planar image. Further, below the “printing direction” data input field F3, a check box F6 for setting “rotational printing” is provided. This check box F6 is for rotating the print job by 180 degrees. Specifically, the print rate distribution for the print job printed last time is compared with the print rate distribution for the print job printed this time. When the print rate distribution is continuous in the longitudinal direction, the page image obtained from the print job to be newly printed is rotated by 180 degrees with respect to the page image of the print job printed last time, and the vertical direction of the print direction is reversed. To do. Here, the vertical direction and the longitudinal direction (direction) are different directions, and the vertical direction represents the direction connecting the leading edge and the trailing edge of the image (paper transport direction), and the longitudinal direction is a direction perpendicular to the vertical direction ( The longitudinal direction of the image carrier is shown.

  The printer driver 22 creates a print job based on the information set from this dialog box DB.

  Returning to FIG. 1, functional blocks implemented in the client 30 are not shown, but include functional blocks similar to the client 20.

  The printer 40 substantially has a computer function, and is a so-called electrophotographic laser printer that forms an image by applying laser light to a charged electrophotographic photosensitive drum, develops it with toner, and transfers it onto a sheet. It is. The printer 40 includes a printer engine 42 as a printing mechanism and a printer control circuit (control means) 44 that realizes a computer function, and constitutes an image forming apparatus of the present invention. As the printer 40, various printers such as an ink jet printer and a thermal transfer printer can be applied.

  The structure and operation of various printers such as the printer 40, other ink jet printers, and thermal transfer printers are well known to those skilled in the art, and thus detailed description thereof is omitted.

  In the printer control circuit 44 of the printer 40, each functional block shown in the figure is constructed by software in order to print a print job. That is, the printer control circuit 44 includes a communication control unit 51 that receives a print job sent from the network 50. Furthermore, a main processing unit 52 that generates output data for printing based on a print job received by the communication control unit 51 and an input / output unit 53 that outputs output data from the main processing unit 52 to the printer engine 42 are provided. . Further, a printing rate analysis unit 54 constituting a printing rate analysis unit, a printing rate comparison unit 55 constituting a printing rate comparison unit, a printing rate storage unit 57 constituting a printing rate storage unit, and a vertical direction control unit are constituted. And a top / bottom direction control unit 56.

  The print rate analysis unit 54 analyzes the print rate distribution for the print job printed this time, and the print rate comparison unit 55 uses the print rate distribution for the print job printed last time and the print rate for the print job printed this time. Compare distributions. The print rate comparison unit 55 stores a print rate distribution for a print job printed last time. When printing the page image, the top and bottom of the output data for printing is the image data received by the communication control unit 51, that is, when printing in the forward direction, and the image data received by the communication control unit 51 is 180 degrees. There are cases where printing is performed in the reverse direction of rotation.

  That is, the analysis result of the longitudinal printing rate distribution is obtained from the printing rate analysis unit 54 for the print job to be printed this time. Longitudinal printing rate distribution is calculated by dividing the image data for one page used for image formation with a mesh for the sent print job, and calculating the ratio of the number of dots on each toner as the printing rate distribution. , Each mesh is integrated in the vertical direction. The print rate comparison unit 55 stores the analysis result of the longitudinal print rate distribution for the print job printed last time. The print rate distribution of the long print rate distribution of the job printed this time and the last printed job is printed. The rate comparison unit 55 compares longitudinal print rate distributions. Thereafter, when it is determined that the printing rate distribution is continuous in the longitudinal direction, the top / bottom direction control unit 56 rotates the page image generated by the main processing unit 52 by 180 degrees as necessary. Here, the continuous printing rate distribution means that the printing rate distribution of the job printed this time and the printing rate distribution of the printing job of the last time match 50% or more, and it shows only the situation where it completely matches. is not. As a result, when the longitudinal printing rate distribution of the job to be printed this time and the job printed last time is 50% or more, it is determined that the printing rate distribution is continuous in the longitudinal direction, and the page image is stored in the printing rate storage unit 55. Control in the opposite direction to the vertical direction. That is, when the top and bottom direction of the page image printed last time is the forward direction, the page direction is switched to the reverse direction. When the top and bottom direction is the reverse direction, the page image is switched to the forward direction. The output data after the switching is sent to the input / output unit 53.

  Each unit 51 to 56 provided in the printer control circuit 44 shown in FIG. 1 is actually realized by a computer program stored in advance in a ROM built in the printer 40 and processing executed by the CPU according to the computer program. Has been.

  Each computer program executed by the printer control circuit 44 is stored in advance in a ROM built in the printer 40. However, instead of this, it may be stored in advance in an external computer-readable recording medium, downloaded from the recording medium, and transferred to the RAM. Examples of this type of recording medium include floppy disks, hard disks, CD-ROMs, magneto-optical disks, IC cards, and the like. These computer programs can also be obtained by downloading program data provided via a network 50 from a specific server connected to the network 50 and transferring it to a RAM.

  FIG. 3 is a flowchart showing a print control routine described by such a computer program. This print control routine is started each time a new print job is input. When the processing is started, the CPU built in the printer control circuit 44 of the printer 40 first receives a print job sent from the network 50 (step S110).

  Next, the CPU executes processing for generating output data for printing based on the print job received in step S110 (step S120). In this process, output data indicating a page image that can be printed out by the printer engine 42 is generated from the image data and control data constituting the print job.

  Here, when the printer property check box F6 is clicked and the user desires “rotate printing” and is instructed to rotate 180 degrees according to the comparison result of the printing rate distribution, the received print job Is transmitted to the printing rate analysis unit 54 (step S125).

  On the other hand, if the printer property check box F6 has not been clicked, the user does not desire “rotate printing”, and if it is not instructed to rotate 180 degrees according to the result of the printing rate comparison, Proceed to S130. That is, an initial operation as a developing device such as toner supply is executed (step S130), and then the process proceeds to step S150.

  Further, the condition determination in step S125 may include the life of the developing device, the residual toner amount, environmental conditions such as temperature and humidity, the total number of print jobs, and the like.

  For example, when the amount of toner in the toner storage chamber decreases near the life of the cartridge including the developing device and a relatively large amount of toner is consumed at one time, the toner supply to the developing device may not be in time. For this reason, with 4000 cartridges as a threshold for 5000 cartridge lifetimes, up to 4000 sheets, even if the user desires “rotational printing”, “rotational printing” is not performed and “rotational printing” is performed after 4000 sheets. The condition may be judged as follows.

  In addition, toner cohesion increases in the toner storage chamber under low temperature and low humidity, so that the toner supply performance deteriorates, and if a relatively large amount of toner is consumed at one time, the toner supply to the developing device may not be in time. . For this reason, when the developing device is used in an environment of 15 ° C./10% Rh or less, the threshold value is set to 3000 sheets for a cartridge life of 5000 sheets. Then, for up to 3000 sheets, even if the user desires “rotational printing”, the condition determination may be made such that “rotary printing” is performed after 3000 sheets without performing “rotational printing”.

  Even when the printing rate is 75%, which is 80% or less, when the total number of print jobs is 50, a relatively large amount of toner is consumed when integrated, and the toner supply to the developing device is not in time. There is. For this reason, when the user desires “rotary printing” and continuously uses a print job with a print rate of 20% or more and 80% or less, the total number of print jobs is set as a threshold value. The condition determination may be made such that “rotary printing” is not performed for up to 20 sheets, and “rotational printing” is performed for 20 sheets or more.

  The print rate analysis unit 54 divides the image data for one page used for image formation for the transmitted print job with a 30 mm × 30 mm mesh, and calculates the ratio of the number of dots on each toner as a print rate distribution. (Step S126). The print job that has been subjected to the printing rate analysis by the printing rate analysis unit 54 is transmitted to the printing rate comparison unit 55.

  If the determination in step S127 is affirmative, that is, if the user desires “rotation printing” and permits the page image to be rotated by 180 degrees in accordance with the comparison of the printing rate distribution, the printing rate comparison unit 55 Perform the process. That is, the print rate distribution for the print job that was printed last time is compared with the print rate distribution for the print job received in step S110. Next, it is determined whether or not a high-printing portion with a printing rate of 80% or more continues in the longitudinal direction across the paper, that is, whether or not the page image needs to be rotated 180 degrees (step S127).

  Here, the printing rate comparison unit 55 obtains the printing rate of the 30 mm × 30 mm mesh in the last row in the paper direction in the print job printed last time obtained by the printing rate analysis unit 54 and 30 mm × 30 mm in the front row in the paper direction of the print job to be printed this time. Compare the printing rate of the mesh. Then, it was determined whether or not a high printing portion having a printing rate of 80% or more continues in the longitudinal direction with a space between the sheets. In this case, an example of the printing rate distribution obtained by the printing rate analysis unit 54 is a printing rate of 80% or more and a 30 mm × 30 mm mesh. As an example of comparison by the printing rate comparison unit 55, the mesh in the last row in the paper direction and the front row in the paper direction Of mesh. However, the printing rate, mesh size, and shape are not limited.

  If it is determined in step S127 that rotation by 180 degrees is necessary, image conversion processing for forcibly rotating the page image indicated by the output data generated in step S120 by 180 degrees is performed (step S140). If it is determined that 180 degree rotation is not necessary, the print job advances to step S150.

  FIG. 4 is an explanatory diagram showing the state of rotation of the page image executed in step S140.

  In the print job 300 printed last time in FIG. 4A, the print rate distribution has a left-right bias, and the right side is a page image with a high print rate. The print job 302 to be printed this time also has a left-right bias in the print rate distribution, and in particular, the right side is a page image with a high print rate. In this way, when the print rate distribution of the print job that was printed last time and the print job that is printed this time is continuous in the longitudinal direction, that is, the page image with the high print rate on the right side is continuous with the paper space in between. This is the case when printing. In this case, the print job 302 to be printed this time is converted into a page image 304 that is rotated by 180 degrees.

  Also, the print job 400 printed last time in FIG. 4B has a vertical deviation in the print rate distribution, and in particular, the lower side is a page image with a high print rate. Further, the print job 402 to be printed this time has a vertical deviation in the print rate distribution, and in particular, the upper side is a page image with a high print rate. As described above, when the print rate distribution of the print job printed last time and the print job printed this time is continuous in the longitudinal direction, that is, the page image having a high print rate is continuously printed with the space between the papers. Is the case. In this case, the page image 404 to be printed this time is converted into a page image 404 that is rotated by 180 degrees.

  Returning to FIG. 3, the process then proceeds to step S150. In step S150, the CPU outputs the output data for printing obtained so far (obtained in step S120 or step S140) to the printer engine. After execution of step S150, the process returns to “return” to end the process of this control routine.

  Step S110 corresponds to the communication control unit 51, step S120 corresponds to the main processing unit 52, step S126 corresponds to the printing rate analysis unit 54, step S127 corresponds to the printing rate comparison unit 55, and S140 corresponds to the vertical direction control unit 56.

  According to the printer 40 of the first embodiment configured as described above, the print rate distribution for the previously printed print job is compared with the print rate distribution for the print job to be printed this time. When it is determined that the print rate distribution is continuous in the longitudinal direction and the image data needs to be rotated by 180 degrees, the page image of the print job to be newly printed with respect to the page image of the print job printed last time is The top-to-bottom direction is reversed.

  Therefore, according to this embodiment, even when a relatively large amount of toner is consumed at a time in a high printing portion, it is possible to reduce the possibility that the toner supply to the developing device will not be in time, and the image density is reduced. High-quality images can be stably formed without image defects such as blurring.

Example 2
Next, a second embodiment of the present invention will be described. Compared with the first embodiment, the present embodiment is different from the first embodiment in that the output paper has the same size and can be switched between the vertical direction and the horizontal direction. In this configuration, as a paper feed cassette for storing paper, a first paper feed cassette for storing paper in the vertical direction while storing paper of the same size, and a second paper feed cassette for storing paper in the horizontal direction are provided. prepare. The paper direction is switched by determining which of the first and second paper feed cassettes is supplied with the paper.

  FIG. 5 is an explanatory diagram showing the “A4” paper feed cassette C1 and the “A4R” paper feed cassette C2. As shown in the figure, although the paper P is the same size as A4, the “A4” paper feed cassette C1 that stores the paper P in the vertical direction and the “A4R” paper feed cassette C2 that stores the paper P in the horizontal direction. Are provided in the printer of this embodiment.

  FIG. 6 is an explanatory diagram schematically showing a paper feed switching configuration in the printer of this embodiment. As shown in the drawing, each of the paper feed cassettes C1 and C2 is provided with a first drive unit M1 and a second drive unit M2 for discharging the stored paper P to the outside of the cassette. Both drive units M1 and M2 operate based on a control command from a cassette selection unit 306 provided in a printer control circuit built in the printer.

  Compared with the first embodiment, the present embodiment differs from the above-described configuration of the paper feed switching mechanism of the printer in the content of the print control routine executed by the CPU, and the other configurations are the same. . FIG. 7 is a flowchart showing a print control routine described by a computer program executed by the CPU. This print control routine is the same in steps S110 to S127 and S150 as compared to the print control routine shown in FIG. 3 in the first embodiment.

  As shown in the figure, when the process is started, the CPU first executes steps S110 to S127 as in the first embodiment. If it is determined in step S127 that the paper direction of the output paper for printing is “A4R”, the CPU advances the process to step S340, and selects the paper cassette to be selected as the paper cassette C2 of “A4R”. Switch. An image conversion process for forcibly rotating the page image indicated by the output data generated in step S120 by 90 degrees in the right direction (or in the left direction) in accordance with the sheet direction of the switched sheet cassette C2. (Step S350). Thereafter, the process proceeds to step S150.

  On the other hand, if it is determined in step S127 that the paper direction of the output paper for printing is “A4”, the process proceeds directly to step S150. In this case, it is assumed that the print job has a specified value, the paper direction of the output paper for printing is defined as “A4”, and the output data is also in the vertical direction.

  According to the present embodiment configured as described above, the print rate distribution for the previously printed print job is compared with the print rate distribution for the print job to be printed this time. When it is determined that the print rate distribution is continuous in the longitudinal direction and needs to be printed in the opposite direction, the output sheet of the new print job is the same as the output sheet printed by the previous print job. The reverse direction. That is, if the output sheet of the print job printed last time is “A4”, the output sheet of the new print job is “A4R”.

  Therefore, according to this embodiment, even when a relatively large amount of toner is consumed at a time in the high printing rate portion, it is possible to reduce the possibility that the toner supply to the developing device will not be in time, and the image density is reduced. High-quality images can be stably formed without image defects such as fading.

  In the first embodiment and the second embodiment, the print control routine directly related to the embodiment of the present invention is configured to be executed by the control circuit built in the printer. However, instead of this, it may be configured to be executed by a print server provided separately from the printer 40.

  In the present invention, the state of the printed matter on the discharge tray is changed between print jobs by the following two modes. That is, in the first embodiment, a printing mode in which a page image is rotated by 180 degrees, and in the second embodiment, a printing mode in which the direction of the printed paper is switched to the opposite direction, that is, by 90 degrees, is rotated. It is.

  However, the present invention is not necessarily limited to these two aspects. In short, as long as the printing mode has a plurality of printing modes in which the longitudinal positions of the print rate distributions of the page image obtained from the print job do not overlap and the state of the printed matter on the discharge tray changes, Can also be applied.

  In the first and second embodiments, the network printer is used as the image forming apparatus. However, the present invention is not limited to this. It may be a stand-alone printer. Further, the image forming apparatus is not limited to the printer, but includes a facsimile machine, a copier, a word processor, and the like. That is, as long as a printing mechanism and a control unit that controls the printing mechanism are provided, the present invention is not limited to a printer and is applied to various image forming apparatuses such as a facsimile machine, a copier, and a word processor.

  Although several embodiments of the present invention have been described in detail above, the present invention is not limited to these embodiments and may be implemented in various modes without departing from the spirit of the present invention. Of course you can.

10 Network system 20, 30 Client 40 Printer (image forming apparatus)
42 Printer engine (printing mechanism)
44 Printer control circuit (control means)
50 Computer Network 51 Communication Control Unit 52 Main Processing Unit 53 Input / Output Unit 54 Print Rate Analysis Unit (Print Rate Analysis Means)
55 Print rate comparison unit (print rate comparison means)
56 Top / bottom direction control unit (top / bottom direction control means)
57 Print rate storage unit (print rate storage means)
60 page image rotation unit 300, 400, 500, 600 Print job 302, 402, 502, 602 printed last time Print job 304, 404, 504, 604 printed this time Page image C1, C2 paper cassette M1, M2 drive unit

Claims (5)

In an image forming apparatus comprising: a printing mechanism; and a control unit that takes in a print job sent from outside and causes the printing mechanism to execute printing according to the printing job.
The control means includes
A printing rate analysis means for analyzing a printing rate distribution of a print job to be printed;
A printing rate storage means for storing a printing rate distribution of a previously printed print job;
A print rate comparison means for comparing a print rate distribution for a print job printed last time and a print rate distribution for a print job printed this time;
A top / bottom direction control means for controlling the page image obtained from the print job to be a top / bottom direction opposite to the top / bottom direction printed last time when the print ratio distribution unit determines that the print ratio distribution is continuous in the longitudinal direction; ,
An image forming apparatus comprising: In an image forming apparatus comprising: a printing mechanism; and a control unit that takes in a print job sent from outside and causes the printing mechanism to execute printing according to the printing job.
The printing mechanism is configured to be able to switch between the vertical direction and the horizontal direction while the paper direction of the output paper is the same size,
The control means includes
A printing rate analysis means for analyzing a printing rate distribution of a print job to be printed;
A printing rate storage means for storing a printing rate distribution of a previously printed print job;
A print rate comparison means for comparing a print rate distribution for a print job printed last time and a print rate distribution for a print job printed this time;
When the print rate comparison unit determines that the print rate distribution is continuous in the longitudinal direction, a paper direction switching control unit that switches the paper direction of the output paper for printing according to the print job to a direction opposite to the paper direction printed last time. When,
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the image forming apparatus is connected to a network connected to a plurality of computers. In an image forming method for capturing a print job sent from the outside and causing a printing mechanism to execute printing according to the print job,
(A) analyzing the print rate distribution for the print job to be printed this time;
(B) comparing the print rate distribution for the previously printed print job with the print rate distribution for the print job printed this time;
(C) controlling to rotate the page image obtained from the print job by 180 degrees when it is determined in step (a) that the print rate distribution is continuous in the longitudinal direction;
An image forming method comprising: In an image forming method for capturing a print job sent from the outside and causing a printing mechanism to execute printing according to the print job,
The printing mechanism is configured to be able to switch between the vertical direction and the horizontal direction while the paper direction of the output paper is the same size,
(A) analyzing the print rate distribution for the print job to be printed this time;
(B) comparing the print rate distribution for the previously printed print job with the print rate distribution for the print job printed this time;
(C) when it is determined in step (a) that the print rate distribution is continuous in the longitudinal direction, the step of switching the paper direction of the output paper for printing according to the print job to the opposite direction;
An image forming method comprising:

Images