JPH09314936A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finish the image processing in an optimum time by implementing the post treatment process of the image formation when both first timing measured by the paper tip detection and second timing measured by the paper rear end detection are satisfied and a print demand signal is not present. SOLUTION: A post treatment process of image formation is implemented when both first timing measured by the timing of the paper tip detection by a detecting means 3 for detecting the tip and the rear end of a conveyed paper with a paper feeding sensor, and a second timing of the paper rear end detection by the detecting means 3 are satisfied and a printing signal is not present with a recording medium conveyed by a paper feeding roller 2c and a conveyance roller 2d. Since the post rotation process can be started at an optimum timing from the rear end detection of the conveyed paper even when the length of the conveyed paper is long, the printing operation can be terminated in minimum necessary time for print finishing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for conveying a recording medium to form an image.

[0002]

2. Description of the Related Art In an image forming apparatus which conveys a recording medium to form an image, a conveying process for finishing the discharge of the recording paper and a process control of the image forming apparatus after finishing the printing for all the printing requests. Therefore, a printing operation end process (hereinafter referred to as post-rotation) is performed for a certain period of time.

Conventionally, the post-rotation is started when there is no print request for the next page at an arbitrary timing when the rear end of the conveyed paper is detected by a sensor provided on the conveying path.

Timing charts of the printing operation in the conventional control are shown in FIGS. 9 (A) and 9 (B).

FIG. 9A is an operation timing chart when the paper feed timing ts1 for a preset paper size and a paper of a prescribed paper size are conveyed.

In FIG. 9, ts1 (sec) is the next page feeding timing measured by the leading edge control from the leading edge detection tk (sec) is the post rotation permission timing counted by the trailing edge control from the trailing edge detection. At this time tk (sec)
Is set to a timing in consideration of the time required to finish the printing operation such as the end of the discharge of the recording paper and the process control in the image forming apparatus. When there is no next page print start request at the time when the timing of tk has passed (print start signal OFF
At that time, that is, when the timing tk shown by the solid line in FIG. 9A has elapsed), the post-rotation process is started.

FIG. 9B is a timing chart of the operation when a paper having a short length in the sub-scanning direction is conveyed.
ts1 and tk have the same settings as in FIG.
At this time, tk <ts1 based on the detection of the leading edge of the paper.
Becomes Therefore, the print operation request signal PRNT becomes tk.
At the timing of <PRNT <ts1, the shift to the post-rotation occurs at tk. For this reason, since the print is accepted (the print start signal is turned ON) during the post-rotation, P is set within the timing of the normal continuous print operation.
Although the RNT is accepted, the post-rotation and pre-rotation processes are performed, and the paper feed for the next page is performed after waiting the paper feed for the time required for these processes.

Further, in a laser beam printer provided with a heat fixing roller capable of rapidly obtaining a high temperature by using a ceramic heater to reduce the heat capacity, a paper having a small size in the main scanning direction, that is, a small width. When paper is passed, heat is not taken away from the part of the heat fixing roller where the paper is not fed, causing the temperature of the heat fixing roller to rise, resulting in uneven fixing of the image or heat. This causes problems such as twisting of the film covering the fixing roller. In order to prevent the above problems and obtain a good image, control is performed to delay the paper feed timing per unit time for a paper having a small width. At this time, (B) of FIG.
The phenomenon described in 1.

[0009]

As described with reference to FIG. 9B, since there is a time timing tk (sec) at which the trailing edge of the conveyed sheet is detected and then the post-rotation is started, there is a time timing tk (sec). When the paper feed permission timing is late, or when the size of the conveyed paper in the sub-scanning direction is short, that is, when the length is short, tk <ts1 and the print request is made within the timing required for normal continuous printing operation. Despite receiving the signal, the printer waits for paper feeding and the printing operation on the next page is delayed.

The present invention has been made to solve the above problems, and it is possible to set an optimum time for a paper size based on which the paper feed timing is determined, regardless of the difference in the actual paper size of the conveyed paper. An object is to obtain an image forming apparatus capable of ending the image forming processing.

[0011]

In order to achieve the above object, the invention of claim 1 is to detect the leading edge and the trailing edge of a conveyed sheet, and to measure the timing from the timing of detecting the leading edge of the sheet by the detecting section. And a control means for executing a post-processing process of image formation when both the first timing and the second timing counted from the timing of the sheet trailing edge detection by the detection means are satisfied and there is no print request signal. It is characterized by having.

Further, the invention of claim 2 is characterized in that, in claim 1, there is a determining means for determining the first timing based on a length of a sheet.

Further, the invention of claim 3 is characterized in that, in claim 2, the determining means inputs the data of the length of the sheet from the outside.

Furthermore, the invention of claim 4 is characterized in that, in claim 2, the determining means measures the length of the sheet based on the timing of the leading edge and trailing edge of the sheet detected by the detecting means. To do.

Furthermore, the invention of claim 5 is characterized in that, in claim 1, there is a determining means for determining the first timing according to the width of the sheet.

Further, the invention of claim 6 is characterized in that, in claim 5, the determining means inputs the data of the width of the sheet from the outside.

Furthermore, the invention of claim 7 is characterized in that, in claim 5, the determining means measures the width of the sheet based on a detection signal from the sheet width detecting means.

Further, the invention of claim 8 is defined by claims 2 to 4.
In any one of the above, the determining means determines the first timing to a value responsive to the letter size when the length of the paper is equal to or smaller than the letter size.

Furthermore, the invention of claim 9 relates to claims 5 to 7.
In any one of the above, the determining means delays the paper feed timing when the width of the paper is smaller than a predetermined value.

Further, the invention of claim 10 relates to claims 1 to 1.
The image forming apparatus according to any one of 9 is one to which an electrophotographic process is applied.

[0021]

FIG. 1 is a sectional view of a laser beam printer showing an embodiment of the present invention.

In FIG. 1, 1 is a laser beam printer main body, 2a is a cassette paper feed port, and 2b is a multi-purpose paper feed port. By driving the paper feed roller 2c and the feed roller 2d, the fed recording medium is fed to feed the paper feed sensor 3
Detects the leading edge and the trailing edge of the paper. Paper width sensor 3b
Detects the length of the conveyed paper in the main scanning direction. Reference numeral 4 denotes a scanner unit, which emits a laser beam modulated by the video data of the image sent through the video interface 13 (see FIG. 2) from the laser emitting unit 4a and reflects it to the polygon motor 4b to generate a horizontal synchronizing signal. A latent image is formed while taking in and scanning the photosensitive drum 5a of the image transfer section 5. The image transfer unit 5 forms an image up to transfer on a recording paper, which is a recording medium to be conveyed, and includes a photosensitive drum 5a, a transfer roller 5b, and other components. Since the image forming process is not directly related to the present invention, the description thereof will be omitted.

A fixing unit 6 has the following 6a and 6b. That is, 6a is a heat fixing roller that covers the ceramic heater, which is a heating body, with a fixing film to apply heat to the recording medium, and 6b is a pressure roller. The fixing unit 6 applies heat and pressure to the recording medium after the transfer process to fix the image.

A paper discharge roller 7 discharges the recording medium passing through the fixing unit 6 to a paper discharge tray 8. The printer engine control unit 9 centrally controls each device based on a control procedure stored in advance.

FIG. 2 is a block diagram of an embodiment of the present invention.

In FIG. 2, the video controller 12 receives coded image information (code data) from the host computer 10 or the like via the external interface 11, converts the code data into dot image video data, and A print command is sent to the engine control unit 9 via the video interface 13, and video data is sequentially sent to the engine control unit 9 in synchronization with the main / sub-scanning synchronization signals from the engine control unit 9.

The DC controller 20 connected to the video controller 12 and the internal video interface 13 is
It has a CPU, a ROM that stores the control procedure of the CPU as shown in FIGS. 4 to 8 described later, and a RAM that has the flags, timers and the like and the work area of the CPU described in FIGS.

The fixing unit 6 has a temperature thermistor 6c, and its value is given to the DC controller 20.
The temperature of is controlled by the DC controller 20. Reference numeral 14 denotes actuators and the like in the printer engine, and reference numeral 15 denotes a transport drive motor for a sheet transport roller, which is controlled by the DC controller 20.

Reference numeral 15 denotes a sensor including the sensors 3 and 3b, which is input to the DC controller 20. The DC controller 20 controls the scanner unit 4 and the image transfer unit 5.

FIGS. 3A and 3B are timing charts showing the operation under the control of this embodiment.

FIG. 3A shows the conveyance paper (in the sub-scanning direction).
7 is an operation timing chart when the length is short.

In FIG. 3A, ts1 (sec)
Is the next page feeding timing measured by the leading edge control from the leading edge detection, ts2 (sec) (ts1 <ts2) is the post-rotation permission timing counted by the leading edge control from the leading edge detection, and tk (sec) is the trailing edge detection from the trailing edge detection. This is the post-rotation permission timing measured by the rear end control. At this time, tk (se
c) is the minimum time required for discharging the paper and ending processing such as process control in the laser beam printer by starting the post-rotation processing after detecting the trailing edge of the conveyed paper by the paper feed sensor 3. Set. When the trailing edge detection is early because the next page feeding timing is long and the length (in the sub-scanning direction) is short, the timing is tk <ts1 <ts2, as shown in FIG. In the printer control of the present invention, the start of the post-rotation processing is permitted only when there is no print start request for the next page at the time when both the timings ts2 and tk have passed, so the signal PRNT for the print start request is tk.
Even when the timing is <PRNT <ts1, it is possible to perform the sheet feeding and the continuous printing operation at the sheet feeding timing without shifting to the post-rotation. When there is no print start request, the post-rotation process is started at the timing of ts2 from tk <ts2.

FIG. 3B is an operation timing chart when the paper size in the sub-scanning direction is long.

In FIG. 3B, ts1 (sec)
Is the next page feeding timing measured by the leading edge control from the leading edge detection. The next page is fed before the trailing edge of the conveyed sheet is detected, so that the sheet can be fed at an early timing. ts2 (sec) is the post-rotation permission timing measured by the tip control from the tip detection, tk (sec)
Is the rear rotation permission timing measured by the rear end control from the rear end detection, and is set to the same time as tk described in FIG. When the trailing edge detection is slow because the next page feeding timing is short and the length (in the sub-scanning direction) is long, the timing is ts1 <ts2 <tk as shown in FIG.

In the printer control of the present embodiment, if there is a print start request signal PRNT before the time tk necessary and sufficient for shifting to the post-rotation after detecting the trailing edge of the conveyed paper, the immediately following page is displayed. When the continuous printing operation is performed and the signal PRNT of the print start request is not present, the printing operation of the printer can be completed in an optimum time by shifting to the post-rotation at the timing of tk.

FIG. 4, FIG. 5 and FIG. 6 are flow charts for explaining the control contents of this embodiment.

FIG. 4 is a flowchart relating to the post-leading-end rotation permission control in the leading-edge control which is started by detecting the leading edge of the conveyed paper by the feed sensor 3.

In FIG. 4, if the tip control timer TS is operating in s101, the process jumps to s105 to perform tip control time monitoring control. If the timer TS is stopped, s1
At 02, the detection of the leading edge of the conveyed paper by the paper feed sensor 3 is monitored. If the tip is detected in s102 (A in FIG. 3A)
1), in s103, the engine controller 9 from the video controller 12 via the video interface 13
Next page feed timing time ts1 determined based on the paper size code of the relevant paper sent, post-tip-control post-rotation permission time ts2 (ts1 <ts2), and other leading-edge control processing time settings. Then, the leading edge control timer TS is started in s104, and proceeds to s105. If the leading edge control timer TS is not ts1 in s105, the process jumps to s108. If TS = ts1 in s105, the presence or absence of a print request for the next page is checked in s106. If there is a print request, next page feed permission is set in s107 (A2 in FIG. 3A). If there is no print request in s106, s
Without performing 107, jump to s108.

If the leading edge control timer TS is not ts2 in s108, the process jumps to s111. TS = in s108
If ts2, the presence or absence of a print request for the next page is checked in s109. If there is no print request in s109, s1
In step 10, the rotation permission flag fs is set after tip control (A3 in FIG. 3A). If there is a print request in s109, the process jumps to s111 without performing s110.

The leading edge control and other processing are performed in s111, the leading edge control timer is checked in s112, and if the leading edge control is not finished, the process returns to s101 and waits until all the leading edge control processing is finished by the timer TS. When the tip control process is completed, the tip control timer TS is stopped in s113 and the tip control is finished.

FIG. 5 is a flowchart relating to the trailing edge rear rotation permission control in the trailing edge control which is started by detecting the trailing edge of the conveyed sheet by the sheet feeding sensor 3.

In FIG. 5, the rear end rearward rotation permission time tk is set in s201. Rear end control timer TK in s202
If is operating, the process jumps to s205 to perform rear end control time monitoring control. If the timer TK is stopped in s202,
In s203, the detection of the trailing edge of the conveyed paper by the paper feed sensor 3 is monitored. If the trailing edge is detected, the trailing edge control timer T is set in s204.
Start K.

If the trailing edge control timer TK = tk is not satisfied in s205, the process jumps to s208. If TK = tk,
In s206, it is checked whether or not there is a print request for the next page.
If there is no print request, the rotation permission flag fk after rear end control is set in s207. If there is a print request, s2
Jump to s208 without performing 07.

The rear end control and other processing are performed in s208, the rear end control timer is checked in s209, and if the rear end control is not finished, the process returns to s202 until the timer TK finishes all the rear end control processes. stand by. When the trailing edge control process is completed, the trailing edge control timer TK is stopped in s210, and the trailing edge control is finished.

FIG. 6 is a flowchart relating to the post-rotation transition monitoring control in the normal rotation state.

In FIG. 6, the flag fs for permitting rotation after tip control is checked in s301, and if it is not set, s30
Jump to 4. If it is set, the flag fk for permitting rotation after rear end control is checked in s302, and if it is not set, s
Jump to 304. If both the flag fs and the flag fk are set, the normal rotation print control ends, and s3
At 03, the process proceeds to the start of post-rotation processing.

As described above, in the present embodiment, the determination of permission to start the post-rotation of the conveyed sheet is made by issuing the print request for the next page after both the timing from the leading edge detection and the timing from the trailing edge detection have passed. By performing post-rotation processing when there is no print request, the print end processing is optimized even if the size of the conveyed paper is different from the paper size for which the paper feed timing is set. You can finish at the timing.

FIG. 7 and FIG. 8 show flow charts of the rear end tip rotation permission ts2 setting control in the above embodiment.

When a unique paper size code is not designated by the video controller 12, as shown in FIG. 7, the paper feed sensor 3 measures the time from leading edge detection to trailing edge detection to determine the paper size. The measurement is performed, and the post-tip rearward rotation permission time ts2 is determined as shown in FIG. FIG. 7 shows a flowchart of paper size measurement and paper size information setting processing. FIG. 8 shows a flowchart of the post-tip rearward rotation permission ts2 setting control.

In FIG. 7, in s401, the paper feed sensor 3 monitors the detection of the leading edge of the recording paper. If the tip is detected, s4
At 02, the paper size timer Tsiz is started. s4
At 03, the paper feed sensor 3 monitors the trailing edge detection of the recording paper.
When the trailing edge is detected, the paper size timer Tsiz is stopped in s404. The value of Tsiz measured in s405 is compared with the maximum letter size value. If the letter size is less than the maximum value, 1 is set in the buffer psizeset in s406. If not, the measured Tsi in s407
The value of z is compared with the maximum value of A4 size. If A4 size maximum value or less, 2 in buffer psizeset in s408
Set. If not, the buffer p in s409
Set 3 in set.

In FIG. 8, at s501, the paper width sensor 3b.
Then, it is checked whether or not the length, that is, the width of the conveyed recording paper in the main scanning direction is less than a certain fixed value. If it is less than, it is determined that the paper is narrow and the paper feed timing ts
When 1 is set to be longer, in s502, the post-tip rotation permission ts2 is set to a small width value (ts1 <ts2). If it is not a small size paper, the video controller 12 is set in s503.
Check the paper size code sent by. If the paper size is designated, the process jumps to s509 to set the front-end / post-rotation permission ts2 according to the paper size. If the paper size is not specified, the buffer psizeset is checked in s504. The buffer psizeset = 1 is checked in s504, and if = 1, rotation is allowed after the tip end t in s505.
Set the letter value to s2. If not = 1 s506
Then, the buffer psizeset = 2 is checked, and if it is = 2, the A4 value is set to the post-tip rotation permission ts2 in s507. = 2 is not satisfied, the end rearward rotation permission ts2 is entered in s508.
Set the legal value to. If the paper size is specified, s5
The paper size code is checked at 09, and if it is a legal code, a legal value is set to the post-tip rearward rotation permission ts2 at s510. If it is not a legal code, the paper size code is checked in s511, and if it is A4, the A4 value is set in the post-tip rotation permission ts2 in s512. If it is not the A4 code, a letter value is set in the front end rearward rotation permission ts2 in s513.

By the above control, when the length of the actually conveyed recording sheet in the sub-scanning direction is shorter than the letter size and the trailing edge detection is fast, the letter value is set to the uniform leading edge rearward rotation permission ts2. When it is detected that the length of the recording sheet in the main scanning direction is short, a small size value is set for the front-end / post-rotation permission ts2 along with the setting of the sheet feeding timing.

[0053]

As described above, according to the present invention,
The image forming process can always be completed in the optimum time regardless of the paper size. Further, according to the present invention, (1) even when controlling the paper feed timing with delay, if there is a print request within the continuous print time even if the length of the conveyed paper is shorter than the specified paper size. Therefore, it is possible to obtain the image forming apparatus capable of performing the continuous printing operation without starting the post-rotation processing.

(2) Even if the length of the conveyed paper is longer than the specified paper size, the post-rotation processing can be started at the optimum timing from the detection of the trailing edge of the conveyed paper, and the printing end processing can be performed. The printing operation can be completed in the minimum required time.

(3) An image forming apparatus with low power consumption can be obtained.

(4) It is possible to extend the life of the photosensitive drum and many other parts.

(5) The above-mentioned operations (1) and (2) can be performed with respect to the paper size on the preset sequence regardless of the length of the actually passed paper, and user-friendly image formation is possible. You can get the device.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating a configuration of a laser beam printer showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an image forming apparatus according to the same embodiment.

FIG. 3 is a view showing a timing chart showing the operation contents of the same embodiment.

FIG. 4 is a flowchart showing an example of control contents of the same embodiment.

FIG. 5 is a flowchart showing another example of control contents of the same embodiment.

FIG. 6 is a flowchart showing another example of control contents of the same embodiment.

FIG. 7 is a flowchart showing another example of control contents of the same embodiment.

FIG. 8 is a flowchart showing another example of control contents of the same embodiment.

FIG. 9 is a diagram showing a timing chart for explaining the operation contents of a conventional laser beam printer.

[Explanation of symbols]

 9 DC controller 20 CPU 3 Paper feed sensor 3b Paper width sensor 2c Paper feed roller 2d Conveying roller 6 Fixing unit TS Front edge control timer TK Rear edge control timer fs Rear edge rear rotation permission flag fk Rear edge rear rotation permission flag

Claims (10)

[Claims] 1. A detection means for detecting the leading edge and the trailing edge of a conveyed sheet, a first timing counted from the timing of the sheet leading edge detected by the sensing means, and a timing counted from the timing of the sheet trailing edge detected by the sensing means. An image forming apparatus comprising: a control unit that executes a post-processing process of image formation when both the second timings are satisfied and there is no print request signal. 2. The image forming apparatus according to claim 1, further comprising a determining unit that determines the first timing based on a length of a sheet. 3. The image forming apparatus according to claim 2, wherein the determination unit inputs the data of the paper length from the outside. 4. The image forming apparatus according to claim 2, wherein the determining unit measures the length of the sheet based on the timing of detecting the leading edge and the trailing edge of the sheet from the detecting unit. 5. The image forming apparatus according to claim 1, further comprising a determining unit that determines the first timing according to a width of a sheet. 6. The image forming apparatus according to claim 5, wherein the deciding unit inputs paper width data from the outside. 7. The image forming apparatus according to claim 5, wherein the determination unit measures the width of the sheet based on a detection signal from the sheet width detection unit. 8. The determining device according to claim 2, wherein the determining unit determines the first timing to a value responsive to the letter size when the length of the paper is equal to or smaller than the letter size. Image forming apparatus. 9. The image forming apparatus according to claim 5, wherein the determining unit delays the sheet feeding timing when the width of the sheet is smaller than a predetermined value. 10. An image forming apparatus according to claim 1, to which an electrophotographic process is applied.