JP2008209536A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of shortening waiting time for restarting a printing operation even when the image forming apparatus is stopped due to occurrence of paper jamming and so on. <P>SOLUTION: The image forming apparatus is provided with an abnormality detection sensor detecting the occurrence of a predetermined abnormal state occurring in a printing operation state and a mirror rotation maintaining means for maintaining the rotation of a polygon mirror for a predetermined waiting time without changing the rotation state of the polygon mirror forming a developer latent image on a photoreceptor when the occurrence of the abnormality is detected by the abnormality detection sensor in the printing operation state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., which is unique in controlling a polygon mirror that forms a development latent image on a photosensitive member.

FIG. 1 is a conceptual diagram of a conventional image forming apparatus provided with a polygon mirror to which the present invention can be applied and its driving unit, FIG. 2 is a control block diagram thereof, and FIG. 3 is a diagram before and after printing of the image forming apparatus. It is a time chart which shows a control procedure.
In such an image forming apparatus X, an electrostatic static image is formed on the surface of the rotating photosensitive drum 5 by irradiating light from a laser light source (not shown) to the polygon mirror 3 rotating in the exposure apparatus 1. The
A developing roller 7 provided in the vicinity of the photosensitive drum 5 causes the toner stored in the developing device 9 to adhere to the electrostatic image formed on the photosensitive drum 5 to be visualized.
A toner remaining amount sensor 11 for detecting the remaining amount of toner is provided in the developing device 9.

On the other hand, the sheet P accumulated in the sheet feeding cassette 13 is sent out only by the uppermost sheet by the sheet feeding roller 15, and the leading end of the sheet P is inserted into the gripping portion of the registration roller 19 through the sheet guide 17. , The paper feed roller 15 is stopped.
In the paper feed cassette 13, a paper feed cassette paper remaining amount sensor 21 for detecting the remaining amount of paper is provided.

When the registration of the leading edge of the sheet on the registration roller 19 is completed, the sheet conveyance motor 51 (see FIG. 2) for driving the registration roller 19 starts rotating, and the photosensitive drum 5 that rotates at a predetermined timing. The sheet is fed into a transfer portion between the transfer roller 23 and the toner image formed on the surface of the photosensitive drum 5 is transferred onto the sheet.
Immediately before the registration roller 19, there is provided a registration unit conveyance sensor 25 for detecting a sheet entering the gripping portion of the registration roller 19, and at a predetermined timing from the detection of the leading edge of the sheet by the registration unit conveyance sensor 25, The registration roller clutch 55 (see FIG. 2) for rotating the registration roller 19 is engaged as described above, and the rotation of the registration roller 19 is started.

The sheet on which the toner image has been transferred as described above is further fed and passes through a fixing device 29 having a fixing roller 27, and the toner image is fixed on the sheet.
The fixing device 29 is provided with a fixing unit conveyance sensor 31 that detects a sheet passing through the fixing roller 27, and monitors a paper jam in the fixing device 29.
The sheet discharged from the fixing device 29 is discharged to the discharge tray 35 by the discharge roller 33. The paper discharge tray 35 is provided with a paper discharge tray full sensor 37 that detects that a predetermined amount or more of sheets are stacked.

An openable and closable upper cover 41 for taking out a toner cartridge 39 for supplying toner into the developing device 9 is provided on the upper surface of the image forming apparatus X. The opening and closing of the upper cover 41 is in contact with the upper cover 41. It is detected by an open / close detection switch (not shown) provided.
Reference numeral 43 denotes an operation panel for giving various commands to the image forming apparatus X or displaying the state of each part of the image forming apparatus X.

The control system of the image forming apparatus X is configured around a control unit 100 such as a CPU connected to an engine control circuit 90 as shown in FIG. Detects signals from various sensors such as the amount sensor 21, registration unit conveyance sensor 25, registration unit conveyance sensor 25, fixing unit conveyance sensor 31, paper discharge tray full sensor 37, and toner remaining amount sensor 11, and the stable state of the sheet conveyance motor 51. The signal from the circuit for performing the operation, the signal indicating the stable state of the polygon mirror rotation from the polygon mirror driving circuit 59, and the signal relating to the fixing temperature from the fixing heater driving circuit in the fixing device are input.
In addition, a sheet conveying motor 51 that drives the sheet feeding roller 15, the registration roller 19, and the fixing roller 27, a sheet feeding roller clutch 53 that transmits the rotation of the sheet conveying motor 51 to the sheet feeding roller 15, and a resist that transmits to the registration roller 19. The roller clutch 55, the fixing heater driving circuit 57, and the polygon mirror driving circuit 59 are also connected to the engine control circuit 90, and are all controlled by the control unit 100 constituted by the CPU.

In the image forming apparatus X configured as described above, the control from the start of driving of the paper transport motor 51 that rotationally drives the paper feed roller 15 and the like until the paper after fixing is discharged to the paper discharge tray 35 is as follows. Is executed in this way.
FIG. 3 is a timing chart showing a control procedure until the fixed paper is discharged to the paper discharge tray 35.
As shown in the drawing, when an image formation start signal is input, at a time point A, the drive of the paper transport motor 51 is first started. At the same time, a polygon motor drive signal is output to the polygon mirror drive circuit 59. This drive signal is input to the control unit 100, and the control unit 100 determines the stability of the rotation of the paper transport motor 51 and the rotation of the polygon mirror by the polygon mirror drive circuit 59.

When the rotation of the paper transport motor 51 is stabilized at time B and a stability signal is transmitted to the control unit 100, an ON signal is transmitted from the control unit 100 to the paper feed roller clutch 53, and the paper feed roller clutch 53 is turned on. The paper feed roller 15 starts to rotate, and the paper starts to be conveyed toward the registration roller 19. The time from time A to B is about 0.5 seconds.
Thereafter, the front end of the sheet comes into contact with the registration unit conveyance sensor 25 in about 2.5 seconds (time point C). When the registration unit conveyance sensor 25 detects the leading edge of the sheet, the sheet feeding roller clutch 53 is turned off by the control unit 100, and the sheet stops with the leading end inserted into the gripping part of the registration roller 19.
In order to stabilize the rotation of the polygon mirror, it takes about 5 seconds after the polygon mirror drive signal is input. Therefore, about 2 seconds after the sheet transported as described above is detected by the registration unit transport sensor 25. After that, the rotation of the polygon mirror is stabilized.

  When it is determined by the signal from the polygon mirror drive circuit 59 that the rotation state of the polygon mirror is stable, the control unit 100 sends an ON signal to the registration roller clutch 55 at time D and registers the rotation of the paper transport motor 51. This is transmitted to the roller 19 and the rotation of the registration roller 19 is started. As a result, the sheet is sent out from the registration roller 19 and the registration roller clutch 55 is turned off at a time point (E) calculated from the length of the sheet. At time F, the transfer of the transferred paper to the paper discharge tray 35 is completed. It takes about 7.8 seconds from time A to time F, and this is the total printing time for one sheet.

In addition, when a paper jam or the like occurs, no prior literature relating to maintaining the rotation of the polygon mirror for a predetermined time has been found. Further, Patent Document 1 discloses that a solenoid for operating a branching claw of a paper discharge unit is kept on for a predetermined time when a paper jam occurs. However, there is a problem in preventing the transfer paper from being damaged. Therefore, unlike the present invention, it is not intended to shorten the printing time, so it is not considered to be a reference for the present invention.
JP-A-7-291509

The conventional image forming apparatus performs the printing operation as described above. If a paper jam occurs during the printing operation shown in FIG. 3, the conventional image forming apparatus immediately outputs a drive signal to the polygon mirror 3. Turn off. Therefore, when the user performs the work to clear the paper jam and then resumes the printing work again, the work starts from time A in FIG. 3 and requires a total time of 7.8 seconds until time F again. It is.
Of the total printing time, the time until the paper reaches the registration unit conveyance sensor 25 (between time points A and C) is inevitable as described above. Since it is a time just waiting for the image to stabilize, if a paper jam occurs, the rotation from the polygon mirror 3 is not stopped and the rotation state is maintained. You can prevent it. This time is 2 seconds, which is about 25% compared to the total printing time of 7.8 seconds, which is a loss time that can never be overlooked.

  Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the waiting time for resuming the printing operation even when the image forming apparatus is stopped due to a paper jam or the like. It is to provide an image forming apparatus capable of performing the above.

In order to achieve the above object, the present invention provides:
An abnormality detection sensor for detecting the occurrence of a predetermined abnormal state that occurs in the printing operation state;
In the printing operation state, when the abnormality detection sensor detects that an abnormality has occurred, the rotation state of the polygon mirror that forms the development latent image on the photosensitive member is not changed, and is maintained for a predetermined waiting time. Mirror rotation maintaining means;
Since the image forming apparatus is configured so that the rotational state of the polygon mirror is stable from the beginning when the printing operation is resumed after recovering from the abnormal state, printing is performed as in the past. Each time it is restarted, there is no need for useless waiting time for the rotation state of the polygon mirror to be stabilized, and the printing operation can be completed in a short time.

Examples of such a predetermined abnormal state include a no-feed state detected by a paper cassette cassette remaining amount sensor, a registration roller portion detected by a registration unit conveyance sensor, and a fixing detected by a fixing unit conveyance sensor. Possible causes are a paper jam at a predetermined location such as an apparatus part, a paper discharge tray full state detected by a paper discharge tray full sensor, or a developer low state detected by a toner remaining amount sensor, or a plurality thereof. .
In the above case, if the predetermined waiting time can be set for each cause of abnormality, the waiting time is set according to the individual recovery time for each cause of abnormality. If the time is set appropriately and the time is set longer or shorter than necessary, the processing is delayed, or conversely, the polygon mirror stops before the recovery from the abnormal state is completed. There will be no longer.

  According to one aspect of the present invention, an abnormality detection sensor such as a registration unit conveyance sensor that detects occurrence of a predetermined abnormal state that occurs in a printing operation state is provided, and an abnormality is detected by the abnormality detection sensor in the printing operation state. When it is detected that the occurrence of the occurrence of the abnormal state, the rotation state of the polygon mirror that forms a development latent image on the photosensitive member is maintained for a predetermined waiting time without changing the rotation state. The polygon mirror rotation state has been stable since the beginning when the printing operation was resumed from the beginning, and a wasteful waiting time was required only for the polygon mirror rotation state to be stable each time printing was resumed as in the past. The printing operation can be completed in a short time.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a conceptual diagram showing an outline of a conventional image forming apparatus, FIG. 2 is a block diagram of a control system and the like that controls the printing operation of the image forming apparatus, and FIG. 3 is a printing operation of the image forming apparatus. FIG. 4 is a time chart showing the printing operation of the image forming apparatus according to one embodiment of the present invention in time series, and FIG. 5 is one embodiment of the present invention. 5 is a flowchart illustrating a procedure of printing processing executed by a control unit of the image forming apparatus.
As described above, in the conventional image forming apparatus, when a paper jam occurs during the printing operation shown in FIG. 3, the drive signal to the polygon mirror 3 is immediately turned off. Therefore, when the user performs the work to clear the paper jam and then resumes the printing work again, the work starts from time A in FIG. 3 and requires a total time of 7.8 seconds until time F again. It is.
This total time includes the time until the sheet reaches the registration unit conveyance sensor 25 (between time points A and C) and the time waiting for the rotation of the polygon mirror 3 to be stabilized (between time points C and D). .
On the other hand, in this embodiment, even if a paper jam occurs, the rotation of the polygon mirror 3 is not stopped and the rotation state is maintained for a predetermined time.
This is because, for example, in the case of an abnormal state that can be recovered in a relatively short time, such as simple paper jam or no toner, it is better to maintain the rotation state without stopping the rotation of the polygon mirror 3 as described later. This is because, when the printing operation is started again, the time (between time points C and D) waiting for the rotation of the polygon mirror 3 to be stabilized is shortened.
FIG. 4 shows this state in a time chart, and FIG. 5 shows a processing procedure in a flowchart.

There are several cases in which the image forming apparatus stops based on a cause that can be recovered in a relatively short time. For example, as a paper jam, a paper jam at the registration roller 19 and the fixing device 29 may be considered. When a paper jam occurs at the registration roller 19, the registration unit conveyance sensor 25 detects this paper jam and notifies the control unit 100. When a paper jam occurs in the fixing device 29, the fixing unit conveyance sensor 31 detects this and notifies the control unit 100.
Further, the stop of the image forming apparatus X in the state where there is no paper remaining in the paper feed cassette 13 is detected by the paper feed cassette paper remaining amount sensor 21, which is a simple operation in which an operator supplies paper. It recovers in a short time.
Further, when a predetermined amount or more of paper is discharged onto the paper discharge tray 35, the paper discharge tray full sensor 37 detects this. Also in this case, the discharged sheet is recovered in a short time by a simple operation in which the operator removes the discharged sheet.
Similarly, even when the toner remaining amount sensor 11 detects that the toner in the developing device is less than a predetermined value, the operator can quickly recover by a simple operation of opening the upper cover 41 and replacing the toner cartridge. To do.

Of course, there may be a “stop state that does not recover in a short time” in the image forming apparatus, but in this case, in such a case, the polygon mirror 3 is stopped without maintaining the rotation state.
In order for the control unit 100 to automatically determine whether or not the state can be recovered in such a short time, a storage device provided in a part of the engine control circuit or the like is informed of a “stop state that recovers in a short time”. The “sensor to be detected” is stored in advance.

Subsequently, a control procedure of the polygon mirror 3 according to the present embodiment will be described with reference to FIGS. 5, S1, S2,... Indicate control procedure (step) numbers executed by the control unit 100.
As shown at time G shown at the left end of FIG. 4, during the printing operation, a paper jam occurs at the registration roller 19, and the paper transport motor 51 is automatically stopped. Therefore, stable rotation from the paper transport motor 51 is performed. The processing is started when the transmission of the signal to the control unit 100 is stopped and the paper feed roller clutch 53 and the registration roller clutch 55 are also turned off.

At this time G, the control unit 100 identifies a sensor that causes the image forming apparatus X to stop in step S1 shown in FIG. This identification is determined, for example, because the registration unit conveyance sensor 25, which should be in the ON state only when a sheet is being sent, transmits an ON signal to the control unit 100 even though the sheet is not in the sheet conveyance state. The A paper jam in the fixing device 29 is also determined from the fact that the fixing unit conveyance sensor 31 is on when it is not in the sheet conveyance state.
In the following, regarding the paper discharge tray full sensor 37, the paper feed cassette paper remaining amount sensor 21, and the toner remaining amount sensor 11, when an ON or OFF signal is input, it is immediately determined that there is an excess of paper, no paper, or no toner.
When the sensor causing the stop of the image forming apparatus X is specified in this way, the control unit 100 reads the “short” stored in the predetermined storage means provided in the engine control circuit 90 in advance as described above. It is determined whether or not the sensor is a sensor that detects a stop state that recovers in time.

However, as described above, when it is determined that it is not a “sensor for detecting a stop state that recovers in a short time” (NO in S1) stored in a predetermined storage unit as shown in FIG. 100 sends a signal to stop the polygon motor to the polygon mirror drive circuit 59 (S5).
If it is determined in S1 that it is a “sensor that detects a stop state that recovers in a short time” (YES in S1) stored in advance in a predetermined storage means, the rotation of the polygon motor as shown in FIG. In other words, the signal to the polygon mirror drive circuit 59 is maintained unchanged (S2).
At the same time, the control unit 100 sets a predetermined waiting time in a timer (not shown) in the control unit 100 and starts the timer (S3). The waiting time may be uniformly 10 seconds, for example, but it is known that the time required for the restoration work varies somewhat depending on the cause of the stop of the image forming apparatus X. Therefore, the cause of the stop determined in S1 is described above. Different waiting times may be stored in advance depending on the type of the sensor indicating, and the waiting time may be changed depending on the type of sensor.
In the example shown in FIG. 5, a uniform case is handled.

Next, in S4, the control unit 100 determines whether or not the time counted by the timer has reached the set predetermined waiting time.
If it is determined that the set waiting time has elapsed (YES in S4), control unit 100 sends a stop signal to polygon mirror drive circuit 59 to stop the polygon mirror.
If it is determined in S4 that the set waiting time has not yet elapsed (NO in S4), the control unit 100 responds to the sensor that has been turned on that caused the image forming apparatus X to stop. It is determined whether the recovery process to be completed is completed.
If the cause of the stoppage is, for example, a paper jam in the registration roller 19, the control unit 100 determines that the recovery process has been completed by receiving an OFF signal from the registration unit conveyance sensor 25 by recovering the paper jam. .
Regarding a paper jam in the fixing device, it can be determined that the recovery process is completed when the signal from the fixing unit conveyance sensor 31 is turned off.
Regarding the paper discharge tray full sensor 37, the paper feed cassette paper remaining amount sensor 21, and the toner remaining amount sensor 11, it is determined that the state of excess paper, no paper, or no toner has been eliminated by inverting the ON or OFF signal. Is done.
Here, as described above, when an off signal is transmitted from the registration unit conveyance sensor 25 as an example to the control unit 100 (when it is determined that the paper jam processing in the registration unit is completed) (YES in S6), It is then determined whether or not the copy button has been pressed to resume printing (S7).

If it is determined that the copy button has been pressed, the printing operation is started (S8). That is, as shown at time H in FIG. 4, the paper transport motor 51 is driven, and the rotation of the paper transport motor 51 is stabilized after about 0.5 seconds.
At this time, since the polygon mirror 3 maintains the rotation state in S2, a waiting time (2 seconds in FIG. 3) is required until the polygon mirror 3 from time C to D in FIG. Thus, the total printing time until the paper is discharged is shorter by 2 seconds than the conventional case of FIG. 3, that is, 5.8 seconds.

  If it is determined in S6 that the process for the paper jam detected by the registration unit conveyance sensor 25 has not been completed, or if it is determined in S7 that the copy button has not been pressed, the process proceeds to S4. Returning, it is determined whether or not the waiting time set in the timer has elapsed.

In the present embodiment, as described above, an abnormality detection sensor such as the registration unit conveyance sensor 25 that detects the occurrence of a predetermined abnormal state that occurs in the printing operation state is provided. When the occurrence of an abnormality is detected by the above, the rotation state of the polygon mirror that forms the development latent image on the photosensitive member is maintained for a predetermined waiting time without being changed. From the beginning when the printing operation is resumed after recovering from the abnormal state, the polygon mirror rotation state is stabilized, and a wasteful waiting time is necessary only for the polygon mirror rotation state to be stable each time printing is resumed as in the past. The printing operation can be completed in a short time.
Examples of such a predetermined abnormal state include a no-feed state detected by the sheet cassette sheet remaining amount sensor 21, a registration roller portion detected by the registration unit conveyance sensor 25, and a detection by the fixing unit conveyance sensor 31. One or more of a paper jam state at a predetermined location such as a fixing device portion to be performed, a paper discharge tray full state detected by the paper discharge tray full sensor 37, or a developer shortage state detected by the toner remaining amount sensor 11 It can be considered.

  In the above case, if the predetermined waiting time can be set for each cause of abnormality, the waiting time is set according to the individual recovery time for each cause of abnormality. The time is set appropriately and is not set to a time longer or shorter than necessary.

FIG. 10 is a conceptual diagram illustrating an outline of a conventional image forming apparatus. FIG. 6 is a block diagram of a control system and the like that controls a printing operation of a conventional image forming apparatus. 6 is a time chart showing a printing operation of a conventional image forming apparatus in time series. 4 is a time chart showing the printing operation of the image forming apparatus according to the embodiment of the present invention in time series. 6 is a flowchart illustrating a procedure of print processing executed by the control unit of the image forming apparatus according to the embodiment of the present disclosure.

Explanation of symbols

X ... image forming apparatus 1 ... exposure apparatus 3 ... polygon mirror 5 ... photosensitive drum 7 ... developing roller 9 ... developing apparatus 11 ... toner remaining amount sensor 13 ... paper feed cassette 15 ... paper feed roller 17 ... paper guide 19 ... registration roller 21 Paper feed cassette paper remaining amount sensor 23 Transfer roller 25 Registration portion conveyance sensor 27 Fixing roller 29 Fixing device 31 Fixing portion conveyance sensor 33 Paper discharge roller 35 Paper discharge tray 37 Paper discharge tray full sensor 39 ... toner cartridge 41 ... upper cover 43 ... operation panel 51 ... paper feed motor 53 ... feed roller clutch 55 ... registration roller clutch 90 ... engine control circuit 100 ... control unit

Claims (3)

An abnormality detection sensor for detecting the occurrence of a predetermined abnormal state that occurs in the printing operation state;
In the printing operation state, when the abnormality detection sensor detects that an abnormality has occurred, the rotation state of the polygon mirror that forms the development latent image on the photosensitive member is not changed, and is maintained for a predetermined waiting time. Mirror rotation maintaining means;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein the predetermined abnormal state is one or more of a state in which no paper is fed, a paper jam in a predetermined location, a paper discharge tray full state, and a developer shortage state.   The image forming apparatus according to claim 1, wherein the predetermined waiting time is set for each cause of abnormality.

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