JPH04337764A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 forming an image on a recording medium by electrophotography.

0002

2. Description of the Related Art FIG. 6 is a sectional view of essential parts of an example of this type of image forming apparatus.

In the figure, 1 is a photosensitive drum which is an electrostatic latent image carrier, 2 is a charging roller that uniformly charges the photosensitive drum 1, 3 is a developer that develops the electrostatic latent image, and 4 is a developing device. 5 is a semiconductor laser as a light source; 6 is an optical lens system that focuses the laser beam to form a spot on the photosensitive drum 1; 7 is a laser A rotating polygon mirror that scans the beam on the photosensitive drum 1; 8, the scanned laser beam; 9, a reflecting mirror; 10, a fixing device that fuses the toner image on the paper to the paper; and 11, a paper cassette that loads the paper. , 12 is a paper feed roller that feeds the paper in the paper cassette 11 to the paper transport path, 13 is a registration sensor that detects the leading edge of the paper, and 14 is a sensor that transports the paper and a photosensitive drum when correcting skew by hitting the leading edge of the paper. A registration roller 15 is used to eject the paper that has come out of the fixing device 10. A paper ejection roller 16 is used to detect the presence or absence of paper after the output from the fixing device 10. It is a paper sensor.

Conventionally, in image forming apparatuses that form images on recording media using this type of electrophotography, the image forming sequence is controlled only at a single process speed. This was handled by switching the motor rotation speed.

[0005]

[Problem to be Solved by the Invention] However, in such conventional examples, the scanning density of the laser beam is switched by increasing or decreasing the number of rotations of the rotating polygon mirror 7, so that the scanning density is increased. As a result, the rotation speed of the polygon mirror increases, causing various problems such as wear of the bearing of the scanner motor for driving the rotating polygon mirror 7, collapse of the rotating shaft, rapid decrease in durability, and generation of noise. .

In particular, with current technology, bearings can only be used at a rotation speed of 10,000 revolutions per minute (10,000 revolutions per minute).
000 rpm), and if the rotation speed is higher than that, the configuration of the rotating polygon mirror must be changed significantly.

In order to overcome such inconveniences, switching the process speed has been proposed in Japanese Patent Laid-Open No. 1-224780. When switching the process speed, it is particularly required that there is no interference between the printing process for the paper before switching and the printing process for the paper after switching, and that the switching operation is quick.

The present invention has been made to solve the above-mentioned problems, and the present invention determines and instructs the timing at which process speed switching is possible while monitoring the state of the image forming process being executed, thereby controlling the speed of the recording medium being conveyed. It is an object of the present invention to provide an image forming apparatus capable of increasing the image processing speed by conveying the image at high speed.

[0009]

[Means for Solving the Problems] The image forming apparatus according to the present invention monitors the state of the image forming process being executed for each recording medium and determines the timing at which the image forming process speed can be switched to another process speed. The apparatus is provided with a management means for issuing a determination instruction, and a control means for controlling switching from the image forming process speed set by the setting means to another process speed based on the determination instruction from the management means.

0010

[Operation] In the present invention, the image forming process status being executed for each recording medium is monitored by the management means, and the setting means is set at a speed different from a predetermined image forming process speed until the image forming process is started. The recording medium transport system is switched and set to the process speed, the recording medium is transported at high speed to a predetermined position, and after the image forming process has started, it is switched to the predetermined image forming process speed, and then again after the image forming process has started. The control means controls the setting means to switch and set the recording medium transport system to a process speed different from a predetermined image forming process speed, thereby making it possible to vary the process speed for the recording medium during a series of image forming processes. do.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram illustrating a control configuration of an image forming apparatus according to an embodiment of the present invention.

In the figure, reference numeral 100 receives image code data from an external host computer, develops it into a binary bitmap, communicates with the printer drive unit 101, and collects the internal status of the printer. This is an image control unit that sends signals necessary for printing such as a print request and vertical synchronization to the printer, and outputs developed bitmap image data to the printer in accordance with the timing.

[0013] This image control unit 100 is a host computer or an operation panel 1 operated by a user.
Based on an instruction from 21, a process speed switching instruction can be given to the printer by communication. Reference numeral 101 denotes a printer drive unit that centrally controls each drive unit of the printer according to instructions from the image control unit 100. This printer drive unit 101 controls the temperature of the fixing heater 109, drives/stops the transport motor 110, drives/stops the scanner motor 111, drives/stops each high voltage (primary charger 112, developer 113, transfer device 114), Each roller (paper feed roller 115,
A fuser drive unit 102 and a conveyance motor drive unit 1 are responsible for driving/stopping the registration rollers 116), adjusting the light intensity of the laser 117, sending blinking data, reading input from each paper presence/absence sensor (registration sensor 118, paper discharge sensor 119), etc.
03, scanner motor drive section 104, high voltage drive section 105
, the various roller drive units 106, the laser drive unit 107, the paper sensor input unit 108, etc., respectively.

Reference numeral 120 denotes a process speed switching timing management unit which inputs a process speed switching permission signal to the printer driving unit 101. The printer drive unit 101 switches the rotational speed of the transport motor 110 to either the high speed mode or the low speed mode via the transport motor drive unit 103 in response to a process speed switching permission signal from the process speed switching timing management unit 120. This conveyance motor 110 is connected to the periphery of the photosensitive drum and to each conveyance roller, so that the overall process speed can be changed simply by switching the rotational speed of the conveyance motor 110.

When the process speed switching timing management section 120 receives a process speed switching request from the printer driving section 101, it manages the internal state of the printer and determines whether the process speed switching is possible. As a result, when switching becomes possible, a process speed switching permission signal is output to the printer drive unit 101. Upon receiving this permission signal, the printer drive unit 101 performs a rotation speed switching operation on the conveyance motor drive unit 103. The operations of the printer drive unit 101 and the process speed switching timing management unit 120 will be described below with reference to the flowcharts shown in FIGS. 2 to 4.

In the image forming apparatus configured as described above, the status of the image forming process being executed for each recording medium is monitored by the management means (process speed switching timing management section 120), and the image forming process is started. Until then, the setting means (conveyance motor drive section 103) switches and sets the recording medium conveyance system to a process speed different from the predetermined image forming process speed, conveys the recording medium at high speed to a predetermined position, and after starting the image forming process, , the control means (printer drive unit 101 ) controls the setting means, making it possible to vary the process speed for the recording medium during a series of imaging processes.

The first print sequence process in the image forming apparatus according to the present invention will be described below with reference to the flowcharts shown in FIGS. 2 and 3 and the timing chart shown in FIG.

FIG. 2 is a flowchart showing an example of the first print sequence in the image forming apparatus according to the present invention. Note that (1) to (19) indicate each step.

First, the printer drive section 101 waits for a print signal PRINT from the image control section 100 (1).
, upon receiving the print signal PRINT (timing t1 in FIG. 4), the transport motor is driven at a high speed transport speed (2). Next, the scanner motor 111 is driven (3), and the timing t2 shown in FIG.
~t4, the primary charger 112, the developer 113
, transfer device 114 (4). In this case, since the high process speed has already been set, the high-voltage power supply is applied in the order of the above-mentioned primary charging, development, and transfer, and the pre-multi-rotation control, which is pre-processing of the photosensitive drum 1, is processed at high speed. When it is necessary to change the process conditions due to higher speeds, the high voltage power supply must also be changed. For example, this is a change in the charging frequency, and in development, it is a development bias condition, and when using an alternating current bias, the frequency and voltage are changed. However, in any case, since the apparatus is already capable of setting conditions corresponding to a plurality of process speeds, it can be easily handled.

Next, after the scanner motor 111 stabilizes at a predetermined rotation speed (5), the printer drive section 101 switches the transport motor drive section 103 to the specified process speed at a timing to be described later (FIG. 4). At timing t5) shown in FIG. 2, the conveyance motor 110 is driven at a specified process speed (6), and paper pickup is started and paper feeding is performed (7). Next, the laser beam intensity of the laser 117 is adjusted to a predetermined value (8), and waits for the paper to reach the registration sensor 118 (9). When the leading edge of the paper abuts (timing t7 shown in FIG. 4), a vertical synchronization request signal is output to the image control unit 100 (10). When a vertical synchronization signal is received from the image control unit 100 at timing t8 shown in FIG. 4 (11), the start of laser irradiation to the photosensitive drum is permitted (12).

Next, the registration rollers are started to be driven (13), and the process waits until the paper discharge sensor 119 detects the trailing edge of the paper (14). After the paper ejection sensor 119 detects the trailing edge of the paper, the printer drive unit 101 waits for a time T0 until the paper is completely ejected from the machine (15), and then the printer drive unit 101 causes the transport motor drive unit 103 to move the paper as shown in FIG. At the timing t10 shown in FIG. 4, the switch to the high process speed is performed again, and the transport motor 110 is driven at the high process speed (16), and the timing t11 to t1 shown in FIG.
3, the high voltage is turned off in the order of transfer device 114, developer 113, and primary charger 112 (17), and at timing t14 shown in FIG. 4, the scanner motor 111 is stopped (18).
), the conveyance motor 110 is stopped (19), and printing of one page is completed.

On the other hand, at this time, the process speed switching timing management section 120 executes processing as shown in FIG.

FIG. 3 is a flowchart showing an example of a process speed switching permission processing procedure by the process speed switching timing management section 120 shown in FIG. Note that (1) to (4) indicate each step.

First, it is determined whether the speed change requesting flag from the printer drive unit 101 is set (1), and if the speed change request flag is set, the transport motor 110 is driven in high speed mode. If the answer is NO, wait for the end of the high voltage rise (4), and when the high pressure rises, return to step (3).

On the other hand, if YES in step (2), the speed switching permission bit is set (3), and the printer drive section 101 is notified that the switching is possible, and the process ends. Conversely, if the motor is being driven, it remains in a wait state until it is stopped.

In this way, the printer drive unit 101 is configured as shown in FIG.
While controlling the printing process shown in , the switching permission bit from the process speed switching timing management section 120 is checked, and if the permission flag is set,
The rotation speed for the next drive is instructed to the transport motor drive section 103. Then, the print signal PRI
The rotational speed of the transport motor 110 when receiving the NT is based on the process speed switching instruction.

As described above, in this embodiment, since at least two types of process speed switching means, high speed mode and low speed mode, are provided, initialization processing for the photosensitive drum that does not directly affect recording on the recording medium can be performed. After executing in high-speed mode, recording processing can be executed at a predetermined process speed, and the processing speed can be improved.

FIG. 5 is a flowchart showing an example of the second print sequence in the image forming apparatus according to the present invention. Note that (1) to (23) indicate each step.

First, the printer drive section 101 waits for a print signal PRINT from the image control section 100 (1).
, upon receiving the print signal PRINT, drives the transport motor at a high speed transport speed (2)
. Next, drive the scanner motor 111 (3)
, the primary charger 112, the developer 113, and the transfer device 114 are turned on in this order (4).

Next, after the scanner motor 111 has stabilized at a predetermined rotation speed (5), the printer drive unit 101 switches the transport motor drive unit 103 to a specified process speed at a timing to be described later, and the transport motor 110 is driven at a specified process speed (6), paper pickup is started, and paper is fed (7). Then,
Adjust the laser beam intensity of the laser 117 to a predetermined value (8), wait for the paper to reach the registration sensor 118 (9), and when the paper reaches the registration sensor 118, the BD signal as a horizontal synchronization signal is output. B cannot be obtained normally.
It is determined whether a D error, such as a delay or no output is detected (10), and if YES, the process proceeds to step (22) where the transport motor 1 is activated at a high process speed.
10, executes error processing at the time of DB failure or misprint (23), and ends the process.

On the other hand, if NO in step (10),
When the paper reaches the registration sensor 118 and the leading edge of the paper hits the registration roller, a vertical synchronization request signal is output to the image control unit 100 (11). Then, upon receiving the vertical synchronization signal from the image control unit 100 (12)
, permits the start of laser irradiation to the photosensitive drum (13).

Next, driving of the registration roller is started (14), and a printing failure (misprint) occurs due to, for example, a BD error (for example, a phenomenon in which a normal BD signal suddenly becomes abnormal). Determine whether (1
5), if YES, proceed to step (22) onwards; NO
If so, wait until the paper discharge sensor 119 detects the trailing edge of the paper (16). After the paper ejection sensor 119 detects the trailing edge of the paper, it takes time T until the paper is completely ejected from the machine.
After waiting for 0 (17), printer drive unit 1
01 causes the transport motor drive unit 103 to switch to the high process speed again at the timing described later.
The transport motor 110 is driven at a high process speed (1
8), transfer device 114, developing device 113, primary charger 112
Turn off the high voltage in the order of (19), and then turn the scanner motor 111
(20), and the transport motor 110 is stopped (21).
), finishes printing one page.

[0033] When such an abnormal process occurs, the process time until the next paper feed can be shortened compared to the conventional method by discharging the paper in the high speed mode.

[0034]

As explained above, the present invention provides management that determines and instructs when it is possible to switch from an image forming process speed to another process speed while monitoring the state of the image forming process being executed for each recording medium. and a control means for controlling the switching of the image forming process speed set by the setting means to another process speed based on the determination instruction from the management means. The image forming process can be executed while the process speed is set to either high or low speed, greatly increasing the processing speed especially during non-printing operations, such as during multiple rotations or automatic paper ejection. can be improved.

[0035] Therefore, an excellent effect is achieved in that the step of shortening the first print time and the speeding up of automatic paper ejection can be achieved at the same time without increasing costs.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating a control configuration of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a first print sequence in the image forming apparatus according to the present invention.

FIG. 3 is a flowchart showing an example of a process speed switching permission processing procedure by the process speed switching timing management unit shown in FIG. 1;

FIG. 4 is a timing chart showing an example of a first print sequence in the image forming apparatus according to the present invention.

FIG. 5 is a flowchart showing an example of a second print sequence in the image forming apparatus according to the present invention.

FIG. 6 is a cross-sectional view of essential parts of an example of this type of image forming apparatus.

[Explanation of symbols]

100 Image control section 101 Printer drive unit 103 Conveyance motor drive unit 110 Conveyance motor 118 Registration sensor 119 Paper discharge sensor

Claims (1)

[Claims] 1. A recording medium that develops an electrostatic latent image formed on an electrostatic latent image carrier by blinking a light beam from a light emitting element in accordance with an image signal, and is transported at a predetermined image forming process speed. an image forming apparatus capable of forming an image by transferring and fixing the image onto a recording medium conveying system, the image forming apparatus having a setting means for switching and setting a predetermined image forming process speed and a plurality of process speeds different from the image forming process speed in a recording medium transport system; a management means for determining and instructing the timing at which switching from the image forming process speed to another process speed is possible while monitoring the state of the image forming process being executed for each recording medium; and control means for controlling switching from the image forming process speed set by the setting means to another process speed.