JP2005031272A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus constituted so that the productivity is not reduced unnecessarily even when decision information required to decide a counting time set in an interval timer is not decided at a point of time when recording paper is fed to an image forming path, in the case of counting a minimum time until the following recording paper can be fed after the recording paper is fed to the image forming path by the interval timer. <P>SOLUTION: In the image forming apparatus, when the interval timer is started while the decision information is not decided, a time up to the time-up of the interval timer 121 is changed to a reasonable value on the basis of the decision information when the decision information is decided before the time-up of the interval timer 121. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine that forms and outputs an image on recording paper, and more particularly to an image forming apparatus characterized by control of timing for sending recording paper to an image forming path.
[0002]
[Prior art]
In an image forming apparatus such as a copying machine having a copy function or a digital multifunction machine to which a scanner function, a printer function, a facsimile function and the like are added, an image is usually formed on a recording sheet by using an electrophotographic process. . In the electrophotographic process, a photoconductor is rotated in a constant direction at a constant speed, and while the photoconductor goes around, an electrostatic latent image is formed on the surface of the photoconductor, and this is developed with toner. A series of processes are performed in which the toner image is transferred onto the recording paper conveyed from the paper feed tray, and the surface of the photosensitive member is cleaned after the transfer. Therefore, it is necessary to transport the recording paper at a constant speed in accordance with the rotation of the photosensitive member while the recording paper passes through the transfer portion to which the toner image on the photosensitive member is transferred. It cannot be paused.
[0003]
For this reason, a second paper feed unit that can temporarily stop the recording paper that has arrived from the paper feed tray is provided in front of the conveyance path portion (image formation pass) while the recording paper passes through the transfer location, The recording paper is made to wait in the second paper feed unit until the conditions that can be sent out to the forming pass are met.
[0004]
For example, when image formation is continuously performed on a plurality of recording sheets, recording is performed from the second sheet feeding unit to the image forming path in order to secure a gap between the preceding recording sheet and the succeeding recording sheet. There is a need to limit the minimum time between paper feeds. Therefore, an interval timer for measuring the minimum time of the sending interval is provided, and this is started at the timing when the recording paper is sent out from the second paper feed unit. At the time when both of the conditions for the arrival have been met, control is performed such that the next recording sheet is sent out from the second sheet feeding unit to the image forming pass. After being sent out to the image forming pass, the recording paper is conveyed at a constant speed until it is discharged out of the apparatus.
[0005]
There are two methods for discharging recording paper after image formation: reverse paper discharge with the front and back reversed, and straight paper discharge without reversing, depending on user settings. There is an image forming apparatus configured to be able to switch methods. As indicated by the arrow 900 in FIG. 9, in the case of reverse paper discharge, the recording paper sent from the second paper feed unit 901 to the image forming path 902 first enters the reverse path 903, and the trailing edge of the recording paper branches. When the point A is reached, the reverse roller 904 is driven in reverse, sent from the rear end to the discharge path 905 and discharged. In the case of straight paper discharge, the paper is discharged through a paper discharge conveyance path indicated by an arrow 910.
[0006]
The required time from the leading edge of the recording paper reaching the branch point A to the trailing edge reaching the branch point A depends on the recording paper size (length in the transport direction), and the smaller size is reversed compared to the larger size. The required time is shortened by the shorter distance entering the path 903. Therefore, if the recording paper size is switched from large to small during continuous image formation on multiple recording papers in the reverse paper discharge mode, the paper discharge interval will be longer than the feed interval to the image formation path. Becomes shorter.
[0007]
FIG. 10 shows the timing relationship between the delivery interval to the image forming path and the delivery interval. Even though the feeding interval 920 between the large size recording paper and the small size recording paper is T1, the discharge interval 921 from the image forming apparatus is T1 ′ shorter than T1. When it is necessary to secure the paper discharge interval 922 for T1, the sending interval T2 is set in advance as indicated by a broken line 923 in the drawing in consideration of the time (T1-T1 ′) that is shortened during reversal. , T2 = T1 + (T1−T1 ′).
[0008]
In addition, when the paper discharge method is switched from reverse paper discharge to straight paper discharge, the length of the paper discharge transport path is significantly shortened, so when sending the last page of reverse paper discharge to the image formation path, the interval timer is used. A time keeping time to be set is lengthened in advance to avoid a collision between recording sheets (see Patent Document 1).
[0009]
In some cases, a post-processing device having a function of folding a recording sheet or binding a plurality of recording sheets with staples is connected to the subsequent stage of the image forming apparatus. In order to perform post-processing such as binding of recording sheets by the post-processing device, it is necessary to lengthen the paper discharge interval from the image forming apparatus to the post-processing device by the time required for the execution. Therefore, when a recording sheet to be post-processed is sent out to the image forming pass, a time measured by adding a time for execution of post-processing in advance is set in the interval timer.
[0010]
In this way, the time to be set in the interval timer is determined based on the status of post-processing, the size of the next recording sheet, the presence / absence of switching of the discharge conveyance path, and the like. However, since information (determination information) necessary for determining the timekeeping time may not be determined yet when the recording paper is sent to the image forming pass, in such a case, it is sufficiently long assuming the worst condition. The timekeeping time is set in the interval timer.
[0011]
For example, if the capture of the image data for the next recording paper is delayed from the time when the recording paper is sent to the image formation pass, the size of the next recording paper and the presence or absence of reverse discharge cannot be determined, and the size condition An interval is set in anticipation of the worst case. If it is set to execute post-processing such as stapling when the last page is ejected, if it is unclear at the time when the recording paper is sent to the image formation pass, the last page The interval is set assuming that
[0012]
[Patent Document 1]
JP 2001-277619 A
[0013]
[Problems to be solved by the invention]
When information necessary for determining the time measured by the interval timer is not determined at the time when the recording paper is sent to the image forming path, a sufficiently long time is set in the interval timer in consideration of the worst condition. However, in practice, such a long interval is often not required, and there is a problem that the timing of sending the next recording sheet to the image forming pass is delayed more than necessary, thereby reducing the productivity of the copying machine. .
[0014]
The present invention is intended to solve the above problems, and the present invention provides a minimum time from when a recording sheet is fed to the image forming path until the next recording sheet can be fed to the image forming path. When counting with the interval timer, productivity is unnecessarily lowered even if the information necessary to determine the timing time to be set in the interval timer is not fixed at the time of sending the recording paper to the image forming pass. It is an object of the present invention to provide an image forming apparatus that does not occur.
[0015]
[Means for Solving the Problems]
The invention according to claim 1 includes an interval timer (121) for measuring a minimum time from when a recording sheet is sent out to the image forming path until the next recording sheet can be sent out to the image forming path,
Timer starting means (122) for setting the time measured until time-up to the interval timer (121) and starting the interval timer (121) in synchronization with the timing of sending the recording paper to the image forming path;
This determination is made when the timer starting means (122) starts the interval timer (121) in a state in which the determination information for setting the timekeeping time has not yet been determined, and when the determination information is subsequently determined. Interval condition changing means (123) for correcting the time taken for the interval timer (121) to time up based on the information;
Have
An image forming apparatus characterized by the above.
[0016]
According to the above invention, even when the timer activation means (122) activates the interval timer (121) in a state where the determination information for setting the timekeeping time has not been confirmed, the determination information is confirmed thereafter. At this time, based on this determination information, the time measured until the interval timer (121) expires is corrected and changed. If the determination information is determined before the time-measurement time set at the start-up time is up, the time up to the time-up can be corrected to a more appropriate length according to the determined determination information. In particular, when the time measured based on the determined determination information has not yet elapsed, the time from when the recording sheet is fed to the image forming pass until the time is up is set before the interval timer (121) is started. This can be the same as the case where the determination information is confirmed, and the decrease in productivity can be eliminated.
[0017]
The interval condition changing means is determined based on the determination information that determines the suitability of the timekeeping time set in the activated interval timer, and when it is inappropriate, the timekeeping time until the interval timer times out is determined by the determination information. You may comprise so that it may correct based on. In addition, if the interval timer is started in a state where the judgment information is not confirmed, when the judgment information is confirmed after that, the time is set to an appropriate time determined by the judgment information without judging whether or not the timing time set previously is appropriate. You may comprise so that it may always correct.
[0018]
According to a second aspect of the present invention, the timer starting means (122) counts time when assuming the determination information that takes the longest time when the interval timer (121) is started in a state where necessary determination information is not fixed. 2. The image forming apparatus according to claim 1, wherein time is set.
[0019]
According to the above invention, when the determination information for setting the time measured by the interval timer (121) is not yet determined at the time of starting the timer, the time measured until the time is up is set assuming the worst condition. Even when the confirmation of the time is greatly delayed, there is no problem that the required paper discharge interval cannot be secured or the recording papers collide with each other.
[0020]
In the invention according to claim 3, one of the determination information includes final page information indicating whether or not the recording sheet sent this time to the image forming pass is the final page,
The interval condition changing means (123) determines whether or not post-processing for the recording paper is necessary based on the last page information, and measures the time until the interval timer (121) times out based on the determination result. To fix
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.
[0021]
According to the above invention, the time counting is corrected in relation to the presence or absence of post-processing for the recording paper that has been sent to the image forming pass this time. For example, if the last page information exists at the end of the print data for a plurality of pages, the last page information may not be acquired yet when the recording paper of the last page is sent to the image forming pass. If it is determined that the page is not the last page, post-processing is not necessary, so the time until correction can be shortened by correcting the time measurement.
[0022]
According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second or third aspect, the size of the recording paper is included in one of the determination information.
[0023]
According to the above-described invention, when the size of the next recording sheet that has not been determined at the time of sending the recording sheet to the image forming pass is subsequently determined, the time until the interval timer (121) times out based on this size To correct. If the size of the next recording sheet is unknown at the time when the large recording sheet is sent to the image forming path in the reverse discharge state, the next recording sheet is changed to a small size, and the discharge interval is shortened. Assuming this, the time keeping time longer by that amount is initially set in the interval timer (121). After that, when the next recording paper is found to be large, it can be seen that there is no need for a margin for reducing the paper discharge interval, so the time until the time is up is shortened by correcting the time measurement. be able to.
[0024]
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, the determination information includes information indicating a discharge / conveyance path of the recording paper. .
[0025]
According to the above invention, when the discharge path for the next recording sheet, which has not been determined at the time of sending the recording sheet to the image forming path, is determined later, the interval timer (121) until the time expires based on this is determined. Time is corrected. For example, if the paper delivery path of the recording paper that is currently sent to the image formation path is reverse delivery, and the delivery path of the next recording paper is unknown at the time of delivery, it changes to straight paper delivery and Assuming that the time is shortened, the time keeping time longer by that amount is initially set in the interval timer (121). Thereafter, when it is determined that the next recording paper is reverse paper discharge, there is no need for a margin for shortening the paper discharge interval, so the time until the time is up can be shortened by correcting the time measurement.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
FIG. 2 shows a cross-sectional configuration of the image forming apparatus 10 according to the embodiment of the present invention. The image forming apparatus 10 is referred to as a so-called digital multifunction device having a copy function for reading a document and forming a duplicate image on a recording paper, a printer function for receiving print data from a personal computer or the like, and outputting a corresponding printed matter. It is a device.
[0028]
The image forming apparatus 10 includes an automatic document feeder 20, a reading unit 30, and a printer unit 40. Further, a post-processing device 90 that performs various post-processings on the recording paper that is formed and output by the image forming apparatus 10 is connected to the subsequent stage. The post-processing device 90 has a function of folding recording sheets and binding a plurality of recording sheets with staples.
[0029]
The automatic document feeder 20 has a function of feeding the documents 2 stacked on the document placing tray 21 one by one to the reading portion of the reading unit 30. The double-sided document has a function of reversing the front and back and sending it to the reading unit 30 after single-sided scanning.
[0030]
The automatic document feeder 20 includes a paper feed roller 22 that sequentially feeds the documents 2 stacked on the document placement tray 21 from the top, and a close contact for allowing the document to pass through a contact glass 31 that is a reading position of the document. A roller 23 and a guide roller 24 for guiding the document fed by the paper feed roller 22 along the contact roller 23 are provided. Further, a switching claw 25 for switching the advancing direction of the document that has passed through the contact glass 31, a reversing roller 26 for reversing the front and back of the double-sided document, and a paper discharge tray 27 for discharging the document that has been read are provided. Yes.
[0031]
The reading unit 30 functions to read a document sent by the automatic document feeder 20 and output corresponding image data. The reading unit 30 includes an exposure scanning unit 35 including a light source 33 and a mirror 34, a line image sensor 36 that receives reflected light from the document and outputs an electrical signal corresponding to the light intensity, and reflects the reflected light from the document. A condensing lens 37 that condenses light on the line image sensor 36 and various mirrors 38 that form an optical path for guiding reflected light from the mirror 34 of the exposure scanning unit 35 to the line image sensor 36 are provided.
[0032]
When reading the document fed by the automatic document feeder 20, the exposure scanning unit 35 moves to a reading position below the contact glass 31 and stops, and reads the document conveyed by the contact roller 23 thereon. It has become. When reading a document placed on the platen glass 32, the exposure scanning unit 35 moves from left to right along the lower surface of the platen glass 32 to read a stationary document.
[0033]
The printer unit 40 has a function of forming an image corresponding to image data on a recording sheet by an electrophotographic process. The printer unit 40 includes a laser unit 42 that outputs laser light that is turned ON / OFF according to image data. In addition, the image forming apparatus includes a photosensitive member 43 on which an electrostatic latent image is formed, a charging device 44 disposed around the photosensitive member 43, a developing device 45, a transfer device 46, a separating device 47, and a cleaning device 48. Yes.
[0034]
The photoconductor 43 has a cylindrical shape and is rotated in a certain direction (the direction of arrow A in the drawing) by a driving unit (not shown). The charging device 44 functions to uniformly charge the photoconductor 43 by corona discharge. An electrostatic latent image is formed on the surface of the photoconductor 43 by scanning the surface of the photoconductor 43 that is uniformly charged in this way with laser light that is turned on and off according to image data. The developing device 45 has a function of developing the electrostatic latent image formed on the surface of the photoreceptor 43 as a toner image.
[0035]
The transfer device 46 functions to electrostatically transfer the toner image on the surface of the photoconductor to the recording paper by applying an electric field, and the separation device 47 functions to separate the recording paper from the photoconductor 43 by charge removal. The cleaning device 48 functions to remove and collect the toner remaining on the photoreceptor 43 after the transfer by rubbing with a blade or the like. The collected toner is returned to the developing device 45 through a path not shown. The fixing device 49 functions to press and heat the toner image on the recording paper to fix it on the recording paper.
[0036]
The first paper feed unit 60 has a plurality of paper feed cassettes 61. These usually contain recording sheets of different sizes and types. The first paper feed roller 62 performs a function of feeding recording sheets stored in the paper feed cassette 61 one by one from the top toward the transport unit 70. The conveyance unit 70 passes the recording sheet sent out from the paper feed cassette 61 through a transfer portion between the photosensitive member 43 and the transfer device 46, and further passes through a fixing device 49 downstream thereof (outside the post-processing device). 90) and a reverse path 70b that reverses the front and back of the recording paper that has passed through the fixing device 49 and then merges with the normal path 70a again upstream of the transfer location. Each of the paths 70a and 70b has a large number of conveying rollers 71 at intervals shorter than the feed direction size of the minimum size recording paper.
[0037]
A second paper feed unit 80 is provided in the transport unit 70 just before (upstream) from the transfer position between the photoconductor 43 and the transfer device 46. The second paper feeding unit 80 has a function of temporarily stopping the recording paper conveyed from the paper feeding cassette 61 at the corresponding portion and sending out the recording paper toward the image forming path when conditions for feeding out are met. . The image forming path is a conveyance path from a position where the second paper feeding unit 80 is provided on the downstream side to a position where it passes through the fixing device 49 via the transfer portion. The second paper feed unit 80 is disposed slightly in front of the second paper feed roller 81 that can be switched between a rotating state and a stopped state, and detects that the recording paper has reached the second paper feed unit 80. 2 paper feed sensors 82.
[0038]
A leading edge detection sensor 72 that detects the leading edge of the recording sheet sent out from the second sheet feeder 80 is disposed downstream of the second sheet feeder 80. The electrostatic latent image is formed by the laser unit 42 based on the timing when the leading edge detection sensor 72 detects the leading edge of the recording paper.
[0039]
On the rear side (downstream) of the fixing device 49, a path switching claw 75 for switching the path of the recording paper is disposed. When the path switching claw 75 is set to the horizontal position indicated by the dotted line in the figure, the paper discharge method is straight paper discharge, and the recording paper after fixing goes straight as indicated by the arrow C and is discharged to the post-processing device 90. When the path switching claw 75 is in the inclined position indicated by the solid line in the drawing, the recording paper advances in the direction indicated by the arrow D.
[0040]
In the case of double-sided printing, the recording paper that has advanced in the direction indicated by the arrow D proceeds directly to the inversion path 70b and is recorded on the back surface. When reverse discharge for single-sided printing is selected, the reverse roller 76 is driven in reverse when the trailing edge of the recording paper that has advanced in the direction indicated by arrow D reaches the reverse roller 76 disposed at the branch point. The As a result, the recording paper advances in the direction indicated by the arrow F, the front and back are reversed, and the paper is discharged to the post-processing device 90. That is, the paper discharge conveyance path downstream of the fixing device 49 has the same configuration as that shown in FIG.
[0041]
FIG. 1 is a block diagram mainly showing an electrical configuration of the image forming apparatus 10. The image forming apparatus 10 is connected to a post-processing apparatus 90 and a computer 5 that is a transmission source of print data. The main control unit 100 performs a function of overall control of the operation of the image forming apparatus 10, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an image memory (not shown). Etc. as the main part.
[0042]
The main control unit 100 has a function as a print controller 101 that develops print data received from the computer 5 or the like into image data (raster image data). In addition, the image data acquired from the print controller 101 or the reading unit 30 is sequentially transmitted to the laser unit 42 of the printer unit 40, and the image control unit 102 functions as an image control unit 102 that manages the flow of image data. The image control unit 102 also has a function of enlarging / reducing or rotating the image. In FIG. 1, the thick dashed arrows indicate the flow of image data.
[0043]
The display operation unit 110 includes a liquid crystal display having a touch panel on the surface and various operation switches, and has a function of performing various guidance displays and status displays to the user, and receiving various operations from the user. ing.
[0044]
The printer unit 40 includes a printer control unit 120 for controlling the operation of the printer unit 40. The printer control unit 120 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like as main parts. It receives various control information from the main control unit 100 and performs the function of controlling the operation of the printer unit 40 in detail according to the received control information.
[0045]
The printer control unit 120 includes an interval timer 121, a timer starting unit 122, an interval condition changing unit 123, a first sheet feeding control unit 124, a second sheet feeding control unit 125, a conveyance control unit 126, and process control. It has a function as means 127.
[0046]
The interval timer 121 is a timer that performs the function of measuring the minimum time from when a recording sheet is sent out to the image forming path until the next recording sheet can be sent out to the image forming path. The timer starting unit 122 has a function of setting a time count (interval) until the time is up in the interval timer 121 and starting the interval timer 121 in synchronization with the timing of sending the recording sheet to the image forming pass. Here, the interval timer 121 is started at the same time when the second paper feed unit 80 feeds the recording paper to the image forming path.
[0047]
The interval condition changing unit 123 functions to change the time measured by the timer starting unit 122 after the interval timer 121 is started. Specifically, when the timer activation means 122 activates the interval timer 121 in a state where the judgment information for setting the time measurement is not finalized, and when the judgment information is confirmed thereafter, based on this judgment information. The function of correcting the time until the interval timer 121 is up is achieved.
[0048]
The determination information includes final page information indicating whether or not the recording sheet sent to the image forming pass when the interval timer 121 is activated is the final page of one printed matter, the presence or absence of post-processing, and the size of the next recording sheet , Information indicating whether the next paper discharge path is straight discharge or reverse discharge is included. Note that the determination information is normally determined when the image data relating to the recording sheet next to the recording sheet sent to the image forming pass when the interval timer 121 is started is completed.
[0049]
The first paper feed control unit 124 functions to control the timing for sending a recording paper of a specified size from the first paper feed unit 60 to the transport unit 70. Here, the recording paper is sent out from the first paper feed unit 60 on condition that the image data for the recording paper sent out this time is fixed. The second paper feed control unit 125 functions to control the temporary stop of the recording paper and the resumption of conveyance (sending to the image forming path) in the second paper feed unit 80. Specifically, the recording paper has arrived from the first paper feed unit 60 or the manual feed unit, and the interval timer 121 started when the previous recording paper is sent to the image forming path has timed out. Under this AND condition, the recording paper is sent out from the second paper supply unit 80 to the image forming path.
[0050]
The conveyance control unit 126 functions to control conveyance of the recording paper in the conveyance unit 70. In addition, it has a function of switching the direction of the path switching claw 75 and the driving direction of the reverse roller 76 to control the paper discharge conveyance path. The process control means 127 manages the operation of the photoconductor 43, the charging device 44, the developing device 45, the transfer device 46, the separation device 47, the cleaning device 48, the fixing device 49, and the like, and controls the execution of the electrophotographic process. Fulfill.
[0051]
In the image forming apparatus 10, when printing a printed material composed of a plurality of pages, the rotation of the photosensitive member 43 is maintained from the start to the end of printing of the printed material, and the electrophotographic process is continuously executed. ing. In addition, if it is known that the next printed material will be printed before the printing of the current printed material is completed, the image forming process related to the next printed material following the last page of the current printed material without stopping the electrophotographic process. Are executed continuously. For example, when the execution of printing of the next printed matter is confirmed before the discharge of the final page is completed, the image forming process is continued without stopping the electrophotographic process.
[0052]
Next, the relationship among the timing for determining the image information during the continuous operation, the timing for feeding the recording paper from the second paper feed unit 80, and the setting status of the interval timer 121 will be described with reference to FIG. In the figure, (1), (2), etc. represent page numbers. When the image information of the first page (1) is determined at time M1, the recording paper relating to the page (1) is fed from the first paper feed unit 60. Since there is no preceding recording paper on page {circle around (1)}, when it reaches the second paper feed unit 80 at time M2, page {circle around (1)} is sent as it is to the image forming pass without being paused. At this time, in the example shown in FIG. 3, the image information for the next page {circle around (2)} has already been determined, and the determination information necessary for determining the time measured by the interval timer 121 has been determined. Based on this, an appropriate time (S1) is set and the interval timer 121 is started.
[0053]
The condition for sending the page (2) from the second paper feed unit 80 to the image forming pass was set when the page (2) reached the second paper feed unit 80 and the page (1) was sent to the image forming pass. The interval timer 121 is timed up, and this AND condition is established at time M3. However, the image information for the next page {circle over (3)} is not yet determined at this point in time, and the timing time to be set in the interval timer 121 that is activated when the page {circle around (2)} is sent to the image forming path. Judgment information for determining is not finalized. Therefore, the timer starter 122 sets the time count (S2) that assumes the worst judgment information for which the time count is the longest, and when the page (2) is sent to the image forming pass (time M3), the interval timer 121 is set. to start.
[0054]
After that, at time M4 before the interval timer 121 times out, the image information for the page (3) is confirmed, and the judgment information necessary for determining an appropriate timing time is confirmed. The time keeping time set in the timer 121 is corrected based on this determination information. That is, since it can be seen that the proper timing time to be set when the page (2) is sent out is S3, the elapsed time (M4-M3) after sending the page (2) is subtracted from S3. The time (S4) is set in the interval timer 121.
[0055]
Thereby, the interval timer 121 is timed up at an appropriate time (M5), and the page (3) is sent out from the second sheet feeding unit 80 to the image forming pass at an appropriate interval time. When the time count is not corrected after the activation of the interval timer 121, the sending of the page (3) (shown as (3) 'in the figure) to the image forming path is delayed more than necessary (time M6), and the image forming apparatus The productivity of 10 is reduced. In the present invention, such a decrease in productivity is avoided by correcting the time measurement.
[0056]
Next, an example in which the recording paper size changes during the continuous printing in the reverse paper discharge mode will be described. Assume that the number of sheets to be continuously printed is 5, and the size changes in the order of “size 1 → size 1 → size 2 → size 1 → size 2”. For size 1, the length of the recording paper in the transport direction is longer than size 2.
[0057]
FIG. 4 is a timing chart showing the relationship between the determination timing of the image information and the set state of the interval timer 121 in the case where the above five sheets are continuously printed. FIG. 5 shows a list of control contents of the second paper feed unit 80 and the interval timer 121 when continuous printing is performed at the timing shown in FIG.
[0058]
Each sheet {circle over (1)} to {circle around (5)} is sent out from the first paper feed unit 60 when the corresponding image information is determined. Since the sheet {circle around (1)} is the first page, the delivery condition to the image forming pass is established only when the sheet {circle around (1)} reaches the second paper feed unit 80. Further, since the image information of the sheet (2) has already been determined when the second sheet feeding unit 80 is activated, the recording sheet size from the sheet (1) to the sheet (2) becomes “size 1 → size 1”. It is determined as judgment information that there is no change. Therefore, the timer starter 122 sets an appropriate time (interval timer value T1) in the interval timer 121 when the recording paper size does not change from “size 1 → size 1”, and supplies the sheet (1) to the second feed. The interval timer 121 is activated when the sheet 80 is sent to the image forming path (time N1).
[0059]
The sheet {circle around (2)} is the time when the interval timer 121 started when the sheet {circle around (1)} is sent to the image forming path and the AND condition that the sheet {circle around (2)} has reached the second paper feed unit 80 is satisfied. At N2, the sheet is sent from the second sheet feeding unit 80 to the image forming path. At this time, the image information of the sheet {circle around (3)} is already determined, and it is determined as judgment information that the recording paper size is changed from “size 1 → size 2” from the sheet {circle around (2)} to the sheet {circle around (3)}. Therefore, the timer starter 122 sets the appropriate time (interval timer value T2) in the interval timer 121 when the recording paper size changes from “size 1 → size 2” to the interval timer 121, and then sets the sheet (2) to the second. The interval timer 121 is activated in synchronization with the timing (time N2) of sending from the paper supply unit 80 to the image forming path.
[0060]
When the recording paper size is switched from size 1 (large) to size 2 (small) in the reverse paper discharge state, the paper discharge interval is shorter than the sending interval to the image forming path, so the interval timer value T2 is , The value in anticipation of that, which is longer than the interval timer value T1.
[0061]
For the sheet (3), the time-up of the interval timer 121 started when the sheet (2) is sent to the image forming path and the time when the AND condition that the sheet (3) has reached the second sheet feeding unit 80 is satisfied. At N3, the image is sent from the second paper feed unit 80 to the image forming path. At this time, the image information of the sheet {circle around (4)} is already determined, and it is determined as judgment information that the recording paper size changes from the sheet {circle around (3)} to the sheet {circle around (4)} “size 2 → size 1”. Therefore, the timer starting means 122 sets an appropriate time (interval timer value T3) in the interval timer 121 when the recording paper size changes from “size 2 → size 1”, and the sheet (3) is second fed. The interval timer 121 is activated in accordance with the timing (time N3) sent from the unit 80 to the image forming path.
[0062]
The interval timer value T3 is a delivery interval necessary for continuous printing of size 2 recording paper. When the size is changed from size 2 to size 1, the paper discharge interval becomes longer depending on the size difference, but the paper interval at the transfer location is determined by the delivery interval to the image forming path. Even when the recording paper size changes from 2 to size 1, the interval timer value T3 for continuous printing of size 2 is used.
[0063]
For the sheet (4), the time-up of the interval timer 121 started when the sheet (3) is sent to the image forming path, and the time when the AND condition that the sheet (4) has reached the second sheet feeding unit 80 is satisfied. At N4, the image is sent from the second paper feed unit 80 to the image forming path. At this time, the image information of the sheet (5), which is the next recording sheet, has not been determined, so the recording sheet size of the sheet (5) is unknown and the determination information is not determined. Therefore, the time keeping time (interval timer value T2max) assuming the worst condition is set in the interval timer 121, and the interval timer is synchronized with the timing (time N4) of sending the sheet (4) from the second sheet feeding unit 80 to the image forming path. 121 is started.
[0064]
Thereafter, at time N5 before the time-up of the interval timer 121, the image information for the page {circle over (5)} is confirmed, and the recording paper size is changed from “size 1 → size 2” from the sheet {circle around (4)} to the sheet {circle around (5)}. To be confirmed as judgment information. Therefore, the interval condition changing unit 123 sets the appropriate time when the recording paper size changes from “size 1 → size 2” until the interval timer 121 times out after the page (4) is sent to the image forming pass. For example, the interval timer value set in the interval timer 121 is changed so as to reach a proper time (interval timer value T2). As a result, the effective interval timer value until the time-out of the interval timer 121 becomes T2, and the sheet (5) is sent out to the image forming path at an appropriate interval according to the recording paper size, thereby preventing an extra delay from occurring. The
[0065]
That is, when correction by the interval condition changing means 123 is not performed, page {circle around (5)} is sent to the image forming pass after T2max time has elapsed (time N7) from the sending of page {circle around (4)} (time N4). On the other hand, when the interval condition changing unit 123 corrects it, the start of sending the page (5) to the image forming path is advanced by (T2max-T2) time, and the productivity of the image forming apparatus 10 is improved accordingly. .
[0066]
FIG. 6 shows a control flow for the second paper feed unit 80 when the printing operation illustrated in FIGS. 4 and 5 is performed. It waits for the sheet (recording paper) to reach the second paper feed unit 80 (step S201; N). When it reaches (step S201; Y), it is determined whether this sheet is the first sheet in the current continuous printing. (Step S202). If it is not the first page, it waits for the time-up of the interval timer 121 activated when the previous page is sent to the image forming pass (step S203).
[0067]
In the case of the first sheet (step S202; Y) or when the interval timer 121 times out (step S203; Y), the sheet is sent to the image forming pass (step S204). If the sheet sent out this time is not the final sheet (step S205; N), an interval timer value for regulating the timing of feeding the next recording sheet is set and the interval timer 121 is started (step S206).
[0068]
As the interval timer value, an appropriate value corresponding to the size of the next recording sheet is set when the next recording sheet size is fixed. Specifically, when the recording paper size changes from size 1 (large) to size 2 (small), T2 is changed. When size 1 does not change from size 1 to T1, T1 changes. When size 2 does not change from size 2 to size 2, or When changing from size 2 to size 1, T3 is set. When the next recording paper size is not fixed, an interval timer value T2max is set in consideration of the worst condition.
[0069]
FIG. 7 shows the flow of operations performed by the interval condition changing means 123. This process is executed when the interval timer 121 is started in a state where the determination information is not fixed, and when the determination information is fixed before the interval timer 121 times out. First, it is determined whether or not the size of the next recording sheet is smaller than the size of the recording sheet sent to the image forming pass when the interval timer 121 is activated (step S301). Then, T2 is obtained as an appropriate interval timer value (step S302).
[0070]
It is determined whether the time T2 has already elapsed since the second paper feed unit 80 was activated last time (step S303). If the time has elapsed (step S303; Y), the interval timer 121 is timed up. Change (step S307). As a result, the interval timer 121 has timed up, the AND condition for the arrival of the recording paper to the second paper supply unit 80 is established, and the sending of the recording paper to the image forming path is immediately started. If the T2 time has not yet elapsed since the last activation of the second sheet feeding unit 80 (step S303; N), the remaining time (T2-T) is obtained by subtracting the elapsed time T of the previous activation from T2. This is set in the interval timer 121 and restarted to change the interval (step S304).
[0071]
If the next recording sheet has not changed to a small size (step S301; N), an appropriate interval timer value is T1. Therefore, it is determined whether or not the T1 time has already elapsed since the second sheet feeding unit 80 was activated last time (step S305), and when it has elapsed (step S305; Y), the interval timer 121 is timed up. The state is changed (step S307). As a result, the interval timer 121 has timed up, the AND condition for the arrival of the recording paper to the second paper supply unit 80 is established, and the sending of the recording paper to the image forming path is immediately started. If the T1 time has not yet elapsed since the last activation of the second sheet feeding unit 80 (step S305; N), the remaining time (T1-T) is obtained by subtracting the elapsed time T of the previous activation from T1. This is set in the interval timer 121 to change the timekeeping time (step S304).
[0072]
Note that if the necessity of post-processing becomes a problem as the determination information for determining the timing time set in the interval timer 121, the necessity of post-processing is determined in step S206 of FIG. When post-processing is not necessary, Ta is set as the interval timer value, and when post-processing is necessary, Tb (Tb> Ta) is set as the interval timer value. Tb is an interval timer value that makes the discharge interval longer than usual by the amount of post-processing execution. If the determination information is not confirmed, an interval timer value assuming that post-processing is performed is set as the worst condition.
[0073]
If there is a problem as to whether the paper discharge conveyance path is reversed paper discharge or straight paper discharge as the determination information for determining the time count set in the interval timer 121, in step S206 in FIG. Judging. That is, Tc is set as the interval timer value when the paper discharge transport path does not change, and Td (Td> Tc) is set as the interval timer value when the paper discharge transport path changes from reverse paper discharge to straight paper discharge. Td is longer than Tc to compensate for the reduction in paper discharge interval due to the change from reverse paper discharge to straight paper discharge. If the determination information is not finalized, an interval timer value that assumes a change from reverse paper discharge to straight paper discharge is set as the worst condition.
[0074]
If a plurality of elements such as recording paper size, post-processing, and paper discharge conveyance path become a problem as determination information, an interval timer value taking into account the plurality of elements is set.
[0075]
FIG. 8 compares the productivity of the image forming apparatus 10 when the time measurement time of the interval timer 121 is changed by the interval condition changing unit 123 and when the time is not changed. When the change by the interval condition changing unit 123 is not performed, as indicated by the solid line 401 in the drawing, the judgment information (image information) at the time (time Te) when the recording paper is sent from the second paper feed unit 80 to the image forming path. If the determination information is not fixed, the productivity is greatly reduced even if the determination information is fixed immediately thereafter. On the other hand, when the decision condition is confirmed, when the interval condition changing unit 123 changes the interval to an appropriate interval, the productivity gradually decreases as the decision information decision timing is delayed, as indicated by a broken line 402 in the figure. . In other words, the best productivity that can be obtained when the determination information is confirmed is always ensured.
[0076]
The embodiments of the present invention have been described with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the present invention can be modified or added without departing from the scope of the present invention. included. For example, in the embodiment, a digital multifunction peripheral has been described as an example of the image forming apparatus. However, a copier, a printer, or the like may be used.
[0077]
【The invention's effect】
According to the image forming apparatus of the present invention, when the minimum time from when a recording sheet is sent out to the image forming path until the next recording sheet can be sent out to the image forming path is measured by the interval timer, an appropriate time measurement is performed. Even when the interval timer is activated and the recording sheet is sent out to the image forming pass in a state where the determination information for setting the time has not been determined, the determination information is added to the determination information when the determination information is subsequently determined. Based on this, the time measured until the interval timer expires is corrected. As a result, if the judgment information is finalized before the time count set at startup time is up, the time until the time up is corrected to an appropriate length according to the finalized judgment information, and image formation productivity is required. It will not drop any more.
[0078]
In particular, if the decision information is confirmed before the time measured based on the decided decision information has elapsed, the time from when the recording paper is sent to the image forming pass until the time is up is set before the interval timer is started. This can be the same as the case where the determination information is confirmed, and the decrease in productivity can be eliminated.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a cross-sectional configuration of the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a timing diagram showing a relationship among image information determination timing, recording paper feed timing from the second paper feed unit, and interval timer setting status during continuous operation.
FIG. 4 shows the relationship between the timing of determining image information and the setting state of the interval timer when continuously printing five sheets whose recording paper size changes in the order of “size 1 → size 1 → size 2 → size 1 → size 2”. FIG.
FIG. 5 is a list showing control contents of a second paper feed unit and an interval timer when continuous printing is performed at the timing shown in FIG. 4;
6 is a flowchart showing control of a second paper feed unit in the printing operation illustrated in FIGS. 4 and 5. FIG.
7 is a flowchart showing the operation of the interval condition changing means in the printing operation exemplified in FIGS. 4 and 5. FIG.
FIG. 8 is a characteristic diagram comparing the productivity of the image forming apparatus when the time measured by the interval timer is changed by the interval condition changing means and when the time is not changed by the interval condition changing means.
FIG. 9 is a conceptual diagram illustrating a paper discharge conveyance path that can be switched between reverse paper discharge and straight paper discharge.
FIG. 10 is an explanatory diagram illustrating a relationship between a paper discharge interval and a sending interval to an image forming path when the recording paper size is changed from large to small in reverse paper discharge.
[Explanation of symbols]
2. Manuscript
5 ... Computer
10 Image forming apparatus
20 ... Automatic document feeder
21. Document tray
22: Paper feed roller
23. Contact roller
24 ... Guide roller
25 ... Switching claw
26. Reverse roller
27 ... Output tray
30: Reading unit
31 ... contact glass
32 ... Platen glass
33 ... Light source
34 ... Mirror
35: Exposure scanning unit
36 ... Line image sensor
37 ... Condensing lens
38. Various mirrors
40 ... Printer section
42 ... Laser unit
43. Photoconductor
44 ... Charging device
45. Developing device
46 ... Transfer device
47. Separation device
48 ... Cleaning device
49. Fixing device
60. First paper feeding unit
61: Paper cassette
62: First paper feed roller
70 ... Conveying section
70a ... Normal route
70b ... inversion path
71 ... Conveying roller
72 ... Tip detection sensor
75 ... Course switching claw
76 ... Reverse roller
80: Second paper feeding unit
81: Second paper feed roller
82 ... Second paper feed sensor
90. Post-processing device
100: Main control unit
101: Print controller
102: Image control unit
110 ... display operation unit
120: Printer control unit
121 ... Interval timer
122. Timer starting means
123: Interval condition changing means
124. First paper feed control means
125: Second paper feed control means
126 ... Conveyance control means
127 ... Process control means
900: Paper discharge conveyance path for reverse paper discharge
901 ... Second paper feeding unit
902 ... Image formation pass
903 ... Reverse path
904 ... Reverse roller
905 ... Reverse path
910 ... Straight paper delivery path

Claims (5)

An interval timer for timing the minimum time from when the recording paper is sent out to the image forming pass until the next recording paper can be sent out to the image forming pass;
Timer starting means for setting the time measured until time-up to the interval timer, and starting the interval timer in synchronization with the timing of sending the recording paper to the image forming path;
When the timer starting means starts the interval timer in a state where the determination information for setting the timekeeping time is not fixed, and the determination information is fixed after that, the interval is based on the determination information. An image forming apparatus comprising: interval condition changing means for correcting a time measured until the timer times out. 2. The timer start unit sets a time count assuming a determination information that makes the time count the longest when the interval timer is started in a state where necessary determination information is not determined. Image forming apparatus. One of the determination information includes final page information indicating whether or not the recording paper sent this time to the image forming pass is the last page,
The interval condition changing means determines whether or not post-processing for the recording paper is necessary based on the last page information, and corrects the time measured until the interval timer expires based on the determination result. The image forming apparatus according to claim 1 or 2. The image forming apparatus according to claim 1, wherein one of the determination information includes a size of a recording sheet. The image forming apparatus according to claim 1, wherein one of the determination information includes information indicating a recording paper discharge conveyance path.

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