JPH04151273A - Device for formation of image - Google Patents

Abstract

PURPOSE:To make prefed sheet usable when jamming is happened as an objective sheet for next printing by providing a sheet-feeding means which is capable of making prefeeding of a recording medium, a monitoring means which monitors the state of supply of the recording medium while printing is in process, and a holding means which holds the recording medium in the state of being supplied. CONSTITUTION:As CPU 16 sends a command from a video interface 24 to an engine control section 25 for prefeeding of a recording sheet, a sheet supply roller 10 is driven, and thereby the sheet is fed from a cassette 9. In the case where a sheet feeding delay timer is counted up before detection on the sheet front end is made with a sheet delivery sensor 14, the engine control section 25 recognizes it as jamming in sheet feeding delay and the CPU 16, responding to this, stops developing of code data for the second page into video data. After the jammed-up sheet is removed by an operator and the jamming is cleared, and when the engine control section 25 detects existence of the sheet with a sheet supply sensor 12, the state of prefeeding of the sheet is kept and printing is made on that sheet for recovery from the jamming.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an image forming apparatus that analyzes print information input from a host or the like and forms an image on a recording medium.

[Prior Art 1] Conventionally, in this type of image forming apparatus, the work of converting code data of an image received from a host computer etc. into pixel data is started, and at the same time, the paper, which is a recording medium, is fed to a predetermined position. , advance paper feeding is performed in which the conversion of code data to pixel data is stopped until the work is completed, and paper is advanced paper fed before the printing of the previous page is completed.
In some cases, the printer is configured to increase the number of sheets printed per unit time (throughput).

[Problem to be Solved by the Invention] However, in the above conventional example, when the paper on which the previous page is being printed becomes jammed while the previously fed paper is stopped at a predetermined position, the previously fed paper is stopped at a predetermined position. Since the paper that has been fed is also judged to be the paper in the conveyance path, when clearing the paper jam state, the above-mentioned jam clearing process to remove the previously fed paper is required, which causes problems such as increasing the burden of clearing the jam. was there.

This invention has been made to solve the above problem, and by excluding the paper that was previously fed when a jam occurred during the printing process of the previous page from the paper that is to be cleared from the jam, the paper that was previously fed is removed. It is an object of the present invention to provide an image forming apparatus capable of feeding paper that is on standby as it is as a paper to be subjected to the next printing process.

[Means for Solving the Problems 1] The image forming apparatus according to the present invention includes a paper feeding unit capable of feeding a recording medium to be the next printing target in advance while analyzing print information, and a paper feeding unit capable of feeding a recording medium to be the next printing target during printing information, and The apparatus is provided with a monitoring means for monitoring the transport state, and a holding means for maintaining the feeding state of the recording medium that has been previously fed by the paper feeder based on the transport state of the recording medium determined by the monitoring means.

[Function] In the present invention, while the recording medium to be the next printing target is pre-fed while the paper feeding means is analyzing printed information and is in a feeding standby state, the monitoring means monitors the conveyance state of the recording medium. Based on the conveyance state of the recording medium by the monitoring means, the holding means can hold the feeding state of the previously fed recording medium and exclude it from the recording media to be cleared from the jam. do.

[Embodiment 1] FIG. 1 is a block diagram illustrating a data processing configuration of an image forming apparatus showing an embodiment of the present invention, and 16 is a CPU.
It has a ROM 19 that stores a control program and a RAM 18 that is used as a register, etc., and receives coded image information (code data) from a host computer etc. via an external interface 17, and performs image processing on the code data. Send it to section 2o. The image processing section 20 stores the code data in the RAM 21, analyzes the code data, reads data from the character font stored in the ROM 22 as necessary, converts the code data into dot image video data, It is stored in the frame memory 23. When one page of video data is stored in the frame memory 23, the CPU 16 sends the data to the engine control unit 25 via the video interface 24.
The video data stored in the frame memory 23 is sequentially sent to the engine control section 25 in synchronization with the main/sub-scanning synchronizing signal from the engine control section 25. C0NT is the controller section, and the above 1
It consists of 6 to 24 mag.

Next, the configuration and engine control of the image forming apparatus will be explained with reference to FIG. 2.

FIG. 2 is a sectional view illustrating the configuration of the image forming apparatus shown in FIG. 1, and the same parts as in FIG. 1 are given the same reference numerals. Note that the image forming apparatus shown is a laser beam printer.

In the figure, 1 is the laser beam printer main body (main body),
2 is a photosensitive drum, and 3 is an optical unit that modulates laser light according to video data sent through a video interface 24, and scans the photosensitive drum 2 with a rotating polygon mirror. Reference numeral 4 denotes a folding mirror that returns the scanned laser beam to the photosensitive drum 2. A charger 5 charges the photosensitive drum 2 uniformly. A developing device 6 develops the electrostatic latent image on the photosensitive drum 2 into a toner image. A transfer device 7 transfers the toner image on the photosensitive drum 2 onto a sheet of paper. 8
is a cleaner that collects toner remaining on the photosensitive drum 2 after transfer. A paper feed roller 10 feeds the paper stored in the cassette 9. Reference numeral 11 denotes a registration roller that stops/transfers the paper fed by the paper feed roller 10 at a timing to be described later. 12 is a paper feed sensor, and registration roller 1
The presence or absence of paper fed from paper 1 is detected.

A fixing device 13 fixes the toner image transferred to the paper by applying pressure and heating. A paper discharge sensor 14 detects the presence or absence of paper discharged from the fixing device 13. 15 is a paper discharge tray.

In the image forming apparatus configured as described above, the recording medium to be the next printing target is pre-fed while the print information is being analyzed by the paper feeding means (in this embodiment, the registration rollers 11, etc.), and the recording medium is placed in a paper feeding standby state. During this time, the monitoring means (in this embodiment, the printer engine control section 25 monitors the outputs of the paper feed sensor 12 and the paper discharge sensor 14) monitors the conveyance state of the recording medium (paper). Based on the conveyance state of the recording medium by the monitoring means, the holding means (printer engine control unit 25) is fed in advance and maintains the feeding state of the recording medium waiting at the position where the registration rollers 11 are disposed. , excluded from the recording media targeted for jam removal.

The operation of the printer engine control section 25 will be explained below.

After the printer engine control unit 25 turns on the power,
Checks the internal status of the printer engine, such as whether the temperature of the fuser 13 is in standby mode and whether paper is loaded in the cassette 9, and displays a video to confirm that the printer is ready to receive print commands or prefeed commands. The CPU 16 is notified via the interface 24. C.P.
U16 starts the printing operation by sending a prefeed command and a print command to the printer engine control unit 25 at a timing to be described later.

When the printer engine control unit 25 receives a print command, the charger 5. By turning on the transfer device 7 and rotating the photosensitive drum 2, the surface potential of the photosensitive drum 2 is initialized, the temperature of the fixing device 13 is raised from the standby state to the printing temperature, and the temperature inside the optical unit 3 (not shown) is increased. Performs a pre-rotation operation to start the rotation of the scanner motor. The pre-rotation is completed, the photosensitive drum 2 is initialized, and the fixing device 13
When the temperature reaches the printing temperature and the rotation of the scanner motor becomes stable, if a prefeed command has not been received in advance, the paper is fed from the cassette 9 by the paper feed roller 10, and the paper feed sensor 12 detects the leading edge of the paper. At the detected timing, paper conveyance by the registration rollers 11 is stopped,
A synchronization signal request signal (VSREQ signal) in the sub-scanning direction is sent to the CPU 16 via the video interface 24, and a synchronization signal (VSYN) in the sub-scanning direction is sent from the CPU 16.
C signal) is sent.

In addition, when a prefeed command is received, the paper has stopped at a predetermined position (the position where the leading edge of the paper is detected by the paper feed sensor 12), so the ■5REQ signal is sent and the C
It waits for the VSYNC signal to be sent from the PU16. When CPLI 16 receives ■5REQ signal, VSY
The NC signal is sent to the engine control unit 25 via the video interface 24, and the video data stored in the frame memory 23 is sequentially sent out in synchronization with the main scanning direction synchronization signal (BD double signal).

The synchronization signal in the main scanning direction is configured to be obtained by detecting laser light by an optical sensor (not shown) disposed outside the photosensitive drum 2 and at an equal distance from the photosensitive drum 2.

When the engine control section 25 receives the V S Y N C signal, the registration roller 11 restarts paper conveyance, turns on the developing device 6, and uses the video data sent out via the video interface 24 in the optical unit 3. The laser beam is modulated and the photosensitive drum 2 is scanned by a polygon mirror to form an electrostatic latent image. The electrostatic latent image is turned into a toner image by the developing device 6, the toner image is transferred by the transfer device 7 to the paper conveyed by the registration roller 11 in synchronization with the leading edge position of the image, and the toner image is transferred to the paper by the fixing device 13. The image is fixed and discharged onto the paper discharge tray 15.

Hereinafter, advance paper feeding processing and paper jam processing will be described with reference to the timing chart shown in FIG.

FIG. 3 is a timing chart showing a printing sequence in the image forming apparatus according to the present invention.

In the figure, timing T indicates the timing at which the CPU 16 starts receiving code data from the host computer via the external interface 17. At timing T2, the CPU 16 receives and receives one page of code data from the host computer, and the image processing unit 20 starts to develop the code data into video data.
By setting the brief feed signal, which is the signal of the video interface 24, to "H level" at this timing T2,
The engine control unit 25 is commanded to perform advance sheet feeding. The engine control unit 25 drives the paper feed roller 10 to feed paper from the cassette 9 when the prefeed signal is at "H level" and paper feeding is possible. Timing T3 is the timing at which the fed paper contacts the registration rollers 11, corrects the skew, and starts transporting the paper by the registration rollers 11. timing T4
stops the paper conveyance by the registration rollers 11 at the timing when it detects that the signal of the paper feed sensor 12 becomes "H level" at the leading edge of the paper conveyed by the registration rollers 11, and instructs the CPU 16 to start feeding the paper in advance. The brief feed signal, which is a signal of the video interface 24 to indicate that the above has been performed, is set to "H level". Timing T5 is the timing at which reception of the second page code data from the host computer is started. Timing T6 is the timing when the image processing unit 20 has finished developing the code data of the first page into video data, and the CPU 16 sets the print signal to “H level” to cause the engine control unit 25 to perform a printing operation. command something. At timing T7, when the engine control section 25 recognizes the "H level" of the print signal and is ready for printing, it sends VSREQ to the CPU 16.
By setting the signal to "H level", a synchronization signal in the sub-scanning direction is requested, and the prefeeding signal is set to "L level". Timing is when the CPU 16 receives the VSREQ signal from the engine control section 25 and outputs the VS
This is the timing to send the YNC signal. timing T
9 is a timing at which the engine control unit 25 receives the VSYNC signal and starts transporting the paper by the registration rollers 11.

The timing T IQ is determined by the CPU 16 at timing T8,
That is, this is the timing at which video data transmission is started after being delayed by a time corresponding to the leading edge margin from the transmission timing of the sub-scanning synchronization signal.

Timing T11 is the timing at which it is detected that the signal of the paper ejection sensor 14 at the leading edge of the paper that has come out of the fixing device 13 has become "H level". At timing T1□, the trailing edge of the paper that has come out from the registration roller 11 is detected by the paper feed sensor 12.
This is the timing when it is detected that the signal has become "L level", and at this timing T1□, the registration roller 11
, and allow advance feeding of the second sheet. timing T
T is the timing when the CPU 16 finishes transmitting the first page of video data, releases the first page of video data from the frame memory 23, and develops the second page of code data into video data. Preliminary paper feeding is performed in the same way as for the first page.

Timing T I3 is the timing at which it is detected that the signal of the paper ejection sensor 14 becomes "L level" at the trailing edge of the paper that has come out of the fixing device 13, and this timing T I4
This will confirm that the printed paper has been properly ejected from the machine. From then on, for the same process as for the first page, the timing T
The second page shows the corresponding timing in the timing TT system.

In the figure, time t is from timing T9 to timing T1.
1, the engine control unit 25 sets a paper feed delay timer for t, 10α1 hours at timing T9, and the paper feed delay timer starts counting before the paper ejection sensor 14 detects the leading edge of the paper. If this happens, it is recognized as a paper feed delay jam. Time t5 is timing T1□
In the time from TI3 to timing TI3, the engine control unit 25 controls tゎ+02 at timing T1□.
A paper discharge delay timer is set, and if the paper discharge delay timer counts up before the paper discharge sensor 14 detects the trailing edge of the paper, it is recognized as a paper discharge delay jam. Time tc is the time from timing T9 to timing TI3, and at timing T8, the engine control unit 25 sets a paper ejection delay timer of tc ten α3 hours, and before the paper ejection sensor 14 detects the paper end. If the conveyance delay timer counts up, it is recognized as a conveyance defective jam. Note that the above α1 to α3 are set to times that have a sufficient margin with respect to the case where the paper is transported normally.

Hereinafter, advance paper feeding processing and paper jam processing will be described with reference to the timing chart shown in FIG.

FIG. 4 is a timing chart showing a printing sequence when a jam occurs on a preceding page in the image forming apparatus according to the present invention.

Since the trailing edge of the paper did not come out from the paper ejection sensor 14 even after tb10a2 hours had passed from timing T1
It notifies U16 that a jam has occurred and that printing on the first page has failed due to the jam.

In response to the occurrence of a jam from the engine control unit 25, the CPU 16 stops developing the code data of the second page into video data and waits for the jam state to be cleared. Timing T15 is the timing at which the operator removes the jammed paper and releases the jam. At this timing T+s, the engine control unit 25 is in advance paper feeding, and when the paper feed sensor 12 detects the presence of paper, it keeps the prefeeding signal at "H level" and enters the advance paper feeding state. is maintained, and when there is no paper in advance paper feeding and there is no paper in the paper feed sensor 12, the brief feed signal is returned to the "L level" and the state returns from the advance paper feeding state to the state in which no paper is being fed. Further, if the advance paper feeding is not in progress, it remains normal. Timing T Ill is CP
After U16 has been cleared from the jam by the engine control unit 25, at the timing to start developing the code data of the first page into video data again, if the briefing signal is at "L level", the pre- Set the feed signal to "H level" and set the prefeed signal to "H level"
If so, it is recognized that the paper is being fed in advance, and the prefeed signal maintains the "L level" state.

Thereafter, timing TT6 to TT, , is timing T6
-Same as T to.

In this way, if a jam occurs in the previous paper while it is being fed in advance, there is no need to remove the paper that was previously fed, and since the state in which the paper was being fed in advance is recognized,
The paper can be used to perform jam-covering printing.

Hereinafter, the advance paper feeding process and the delayed paper discharge jam process will be described with reference to the timing chart shown in FIG.

FIG. 5 is a timing chart showing a printing sequence when a paper jam occurs on a preceding page in the image forming apparatus according to the present invention.

At timing T+8, the jam state is released, and at timing T+7, the CPU 16 receives from the engine control unit 25 that the jam state has been released, and then resets the state to 1 again.
At the timing at which the development of page code data into video data is started, the CPU 16 sets the prefeed signal to "H level" as usual, and instructs the engine control section 25 to perform advance sheet feeding. When the engine control unit 25 is in a state in which advance sheet feeding is maintained at timing TI5, the CPU 16 sets the prefeed signal to "H level" and even if it commands advance sheet feeding, the command is ignored and the state remains as it is. hold. In addition, when the state has returned from the advance paper feeding state to the state where no paper is being fed at timing TI5, the advance paper feeding operation is performed according to the advance paper feeding command from CPtJ 16, and thereafter, one page is fed as shown in FIG. Perform eye jam recovery.

In this way, even if a jam occurs in the previous paper in the advance paper feeding state, the CPU 16, that is, the image control unit, will perform the normal printing sequence regardless of the advance paper feeding state, so that the jam occurs. Normal printing can be performed on the paper that was previously fed.

[Effects of the Invention] As described above, the present invention provides a paper feeding means that can advance the recording medium to be printed next while analyzing print information, and monitors the conveyance state of the recording medium during printing processing. and a holding means that maintains the feeding status of the recording medium that is being fed in advance by the paper feeding unit based on the conveyance status of the recording medium determined by the monitoring unit. If a paper jam occurs during printing for some reason, the paper that was previously fed and remains in the machine can be excluded from the jam release paper, and the remaining paper can be fed as the next paper candidate. can be sent.

Therefore, even if a jam occurs while paper is being fed in advance, the operator only has to clear the jam, which greatly reduces the burden on the operator to clear the paper compared to conventional methods. This has effects such as being able to significantly shorten the time required to start the subsequent printing process.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating a data processing configuration of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a sectional view illustrating the configuration of the image forming apparatus shown in FIG. 1, and FIG. 4 is a timing chart showing a printing sequence in the image forming apparatus according to the invention, FIG. 4 is a timing chart showing a printing sequence when a jam occurs on a preceding page in the image forming apparatus according to the invention, and FIG. 5 is a timing chart showing the printing sequence in the image forming apparatus according to the invention. 3 is a timing chart showing a printing sequence when a discharge jam occurs on a preceding page in the image forming apparatus according to the present invention.

Claims (1)

[Claims] In an image forming apparatus that analyzes input print information to form an image on a recording medium, a paper feeding unit capable of pre-feeding a recording medium to be printed next while the print information is being analyzed;
a monitoring means for monitoring the conveyance state of the recording medium during printing processing; and a holding means for maintaining the feeding state of the recording medium that has been previously fed by the paper feeding means based on the conveyance state of the recording medium determined by the monitoring means. An image forming apparatus comprising: