JP2004309519A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of optimum control of a conveyance belt depending on print mode in image formation. <P>SOLUTION: Upon receiving image data, a CPU (central processing unit) 26 transmits a drive start signal to a motor 25. At the same time as the drive of the motor 25, the monitoring of the output of an encoder 19 is started by a speed detection part 22. A speed determination part 23 compares the period of the pulse output of the encoder 19 with a conveyance belt period that is optimum for image formation, and determines whether the present speed of the belt is at a level that printing is possible or not. An image data color distcrimination means 27 verifies whether the image data transmitted is a color image or a monochrome image. In the case of the color image, the image formation is not started until the output of the required speed is confirmed by the speed determination part 23. At the point of time when the output of the required speed is confirmed, an image formation start signal generation part 24 generates an image formation start signal and a series of image formation processes is started. Control may be performed in the same manner according to image quality mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, in particular, a plurality of developing devices are juxtaposed, toner images of respective colors are formed on an image carrier in each developing device, and the toner images are transferred to an endless belt-shaped intermediate transfer member. Further, the present invention relates to a color image forming apparatus configured to retransfer from an intermediate transfer member to a print medium or directly transfer the toner image onto a print medium conveyed by an endless belt.
[0002]
[Prior art]
Conventionally, as an image forming apparatus for outputting this type of color image, a toner image of each color of yellow, cyan, magenta, and black is formed on a photosensitive drum in a developing device of each color, and then the toner images are intermediately transferred. A type in which the image is directly transferred to a print medium via a belt or a conveyor belt and output through a fixing process is used.
[0003]
In such a conventional image forming apparatus, in order to drive the intermediate transfer belt and the conveyance belt at a constant speed, a rib or the like provided on the belt is detected by a sensor, and the conveyance speed of the belt is determined based on the detection result. Is known (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-01-156249 (page 18, upper left column, line 18-same page lower left column, line 11, FIG. 3)
[0005]
[Problems to be solved by the invention]
In the above-described image forming apparatus, the belt such as the intermediate transfer belt is driven at the same time as the image forming process is started, and after a lapse of a certain time from the start of the driving, a portion related to the belt conveyance (the transfer process from the photosensitive drum) is started. ) Is performed.
[0006]
However, the belt speed may not be stable. For example, when the image forming apparatus is left without performing image formation for a long time, or when the life of the image forming apparatus is approaching, the same fixed time as the initial period immediately after the apparatus is manufactured as the stable time from the start of driving. If used, the belt speed is not stable. For this reason, the speed of the belt changes during image formation, and when transferring a plurality of color toner images to the intermediate transfer belt or the print medium, a color shift of each color occurs to adversely affect the image quality. On the other hand, when estimating the stabilization time in advance and performing image formation after the elapse of the estimated fixed time, if the belt speed is stable before the elapse of the certain time, extra time is required for image formation. .
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to solve the problem of color misregistration of a toner image of a plurality of colors due to instability of belt conveyance, and to set a print mode during image formation. An object of the present invention is to provide an image forming apparatus capable of controlling the conveyance belt optimally in accordance therewith, and further broadening the selectivity of giving priority to high image quality and printing speed, and capable of selecting a mode desired by a user.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a plurality of developing devices arranged side by side, forms a toner image of each color on each image carrier in these developing devices, and transfers the toner images to an endless belt-shaped intermediate transfer member. In an image forming apparatus for transferring and retransferring to a print medium or directly transferring onto a print medium conveyed by an endless belt-like transport belt, the endless belt-like intermediate transfer body or the endless belt-like transport belt Belt speed detecting means for detecting the speed of the belt, belt speed determining means for determining that the speed of the intermediate transfer member or the conveyor belt is stabilized based on the detection output of the belt speed detecting means, and the belt speed determining means And an image forming start signal generating means for generating an image forming start timing in accordance with the judgment output.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
(1st Embodiment)
FIG. 1 is a sectional view showing a schematic front vertical sectional structure of a printer which is a representative example of an image forming apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a scanner unit, which includes a semiconductor laser (not shown) and two rotating polygon mirrors. Reference numeral 3 denotes a cartridge for storing the developer and storing waste toner generated when the excess toner on the photoconductor 4 is cleaned. Reference numeral 5 denotes a developing sleeve for developing the electrostatic latent image on the surface of the photoconductor 4 into a toner image. Reference numeral 6 denotes a developing device (hereinafter referred to as a developing cartridge) that collectively includes the cartridge 3, the photosensitive member 4, and the developing sleeve 5, and 6, 7, 8, and 9 denote developing cartridges of yellow Y, magenta M, cyan C, and black BK, respectively. In particular, the order of the colors does not matter.
[0011]
Reference numeral 10 denotes a transfer roller disposed to face the photoconductor 4 to transfer a toner image on the photoconductor 4 developed by each color developing cartridge to a print medium. Reference numeral 11 denotes a transport belt configured by an endless belt for transporting a print medium. In the present embodiment, the transport belt 11 is used as a unit for transporting the print medium. However, a configuration in which an image carrier on the belt is used as a transfer unit can also be used. Reference numeral 12 denotes a sheet feeding unit. Reference numeral 13 denotes a print medium mounted in the paper feed unit 12. Reference numeral 14 denotes a fixing device for fixing the toner image on the printing medium to the printing medium, 15 denotes a fixing roller, and 16 denotes a heater roller for heating the fixing device for fixing.
[0012]
FIG. 2 schematically shows a conveyor belt and a drive system mainly in the belt conveyor of FIG. In FIG. 2, reference numeral 17 denotes a tension roller for keeping the tension of the belt 11 uniform, and reference numeral 18 denotes a driven roller which is rotated by being given a driving force by the transport belt 11. Reference numeral 19 denotes an encoder attached to the shaft of the driven roller 18, which comprises a disk (code wheel) 20 having slits at equal intervals along the circumference and a photo interrupter (light transmission type sensor) 21. As the encoder 19, a reflective optical system, an encoder for reading a magnetic pattern formed in a disk shape, and the like are used.
[0013]
The photo interrupter 21 is disposed so as to sandwich the encoder disk 20. When light of the photo interrupter passes through the slit of the disk, the rotation speed detection signal output from the photo interrupter 21 becomes LOW (low) level. Therefore, when the driven roller 18 is rotated by the driving of the transport belt 11, the disk 20 provided on the roller shaft is rotated, and slits at equal intervals along the circumference are sequentially formed between the light emitting element and the light receiving element of the photo interrupter 21. Sent to For this reason, the rotation speed detection signal output from the photo interrupter 21 has a pulse-like waveform, and the speed of the transport belt 11 can be detected based on how many pulses are detected at regular intervals. Therefore, the higher the resolution of the encoder, the more accurately the rotational speed can be detected.
[0014]
An optical sensor that outputs 1 PULSE (pulse) per rotation of the driven roller 18 may be used for detecting the rotation speed of the transport belt 11. In this case, it is possible to detect the speed of the conveyor belt 11 by measuring the time between PULSE. In addition, as a means for detecting the speed of the conveyor belt 11, there is a method of forming marks and slits on the belt 11 at equal intervals, and reading the marks and slits with an optical sensor.
[0015]
FIG. 3 is a block diagram showing a functional configuration of a signal processing system according to the present embodiment. In FIG. 3, reference numeral 22 denotes a speed detecting unit for monitoring the output of the encoder 19, and reference numeral 23 denotes that a current belt speed monitored by the speed detecting unit 22 with respect to a predetermined belt speed of the conveyor belt (FTB) 11 can be printed. A speed judging unit for judging whether or not the level is a level; 24, an image forming start signal generating unit for forming an image forming start signal based on the judgment result of the speed judging unit 23; 25, a motor as a driving source for driving the transport belt 11; And 26, a CPU (Central Processing Unit) for controlling the image forming apparatus, and 27, an image data color discrimination unit for discriminating the color data of the image data transmitted from the host computer 28.
[0016]
Next, the operation of the above configuration of FIG. 3 will be described. When receiving image data from the host computer 28, the CPU 26 first sends a drive start signal to the motor 25. The motor 25 is controlled to rotate at a predetermined speed. At the same time as the driving of the motor 25, the output monitor of the encoder 19 is started. The speed detector 22 sequentially checks the cycle of the pulse output of the encoder 19. The speed determination unit 23 compares the pulse output period of the encoder 19 with a predetermined conveyance belt period optimal for image formation, and determines whether the current belt speed is at a level at which printing can be performed. Do. The method of determining the speed includes a method of determining the speed based on the number of coincidences of the pulse periods within a certain period, and a method of calculating the average value of the pulse periods within the certain period.
[0017]
Here, the speed determination method will be described.
(1) Method of discriminating the number of coincidences of the pulse period in a certain period
FIG. 4 shows the pulse output of the encoder 19. T is a sampling time, and sampling is repeated at T periods. In this example, five pulses are output within the T period, but the number of pulses is not particularly limited.
[0018]
The period of each pulse is measured for five pulses in the T period. Assuming that each cycle is t1, t2, t3, t4, t5, it is determined whether or not each cycle is the same as TS, which is a stable cycle of the transport belt 11. If the number of coincidences between the pulse period within the T period and the stable period of the TS is, for example, 4 or more, it is determined that the conveyor belt 11 is being driven stably, the speed coincidence is determined, and the speed OK is output. However, the number of matches, which is a criterion, can be arbitrarily set.
[0019]
(2) Method for comparing and discriminating average values of pulse periods during a certain period
Each cycle of five pulses within the sampling time T is measured. Assuming that the respective periods are t1, t2, t3, t4 and t5, the average period Ta is Ta = (t1 + t2 + t3 + t4 + t5) / 5. When Ta calculated here and TS, which is the stable period of the conveyor belt 11, match, the conveyor belt 11 is defined as being driven stably, a speed match is determined, and the speed OK is output.
[0020]
In the above two discrimination methods, the period of the pulse output from the encoder 19 may be any one of a rising edge, a falling edge, and both edges. Further, the sampling of the pulse output of the encoder 19 may be performed by using either a method of updating every fixed period or a method of updating every pulse.
[0021]
The image data color discriminating unit 27 shown in FIG. 3 checks whether the image data transmitted from the host computer 28 is a color image or a monochrome image. If the image data is a color image, the CPU 26 does not start image formation until the speed determination unit 23 confirms the output of the speed OK. When the output of the speed OK is confirmed by the speed determination unit 23, the image formation start signal generation unit 24 generates an image formation start signal, and starts the above-described series of image formation processes.
[0022]
If the image data is a monochrome image, the CPU 26 ignores the output of the speed determination unit 23, generates an image formation start signal in the formation start signal generation unit 24 after a certain time has elapsed from the start of driving of the motor 25, and Starts a series of image forming processes.
[0023]
After generating the image formation start signal, the print medium 13 stored in the paper supply unit 12 is transported to the image forming unit. The transported print medium 13 is attracted to the transport belt 11 and transported to the front edge of the BK (black) developing cartridge 9. Here, the toner image formed on the photoconductor of the BK developing cartridge 9 is transferred onto the print medium 13. From here, the toner images on the photosensitive members of the developing cartridges 8, 7, and 6 are sequentially transferred onto the print medium 13 in accordance with the transport of the transport belt 11, thereby forming a full-color image.
[0024]
If the image data from the host computer 28 is a monochrome image, the CPU 26 conveys the print medium 13 stored in the paper feed unit 12 to the image forming unit before generating the image formation start signal. The transported print medium 13 is attracted to the transport belt 11 and transported to the front edge of the BK developing cartridge 9. Here, the toner image formed on the photoconductor of the BK developing cartridge 9 is transferred onto the print medium 13. Since the image is a monochrome image, the printing medium 13 is directly conveyed to the fixing device 14 according to the conveyance belt 11 and the BK toner image is fixed on the printing medium 13 by the fixing device 14. Is discharged onto a discharge trainer (not shown) outside the apparatus.
[0025]
Next, the flow of the control operation will be further described with reference to the flowchart of FIG. Upon receiving the image data from the host computer 28 (S501), the CPU 26 determines whether the image data is monochrome image data or color image data (S502).
[0026]
If the image data is a monochrome image, an image formation start signal is generated without waiting for the stability of the transport belt 11 (S507), and image formation is started (S508).
[0027]
On the other hand, if the image data is a color image, speed detection of the conveyor belt 11 is started (S503). The cycle of the conveyor belt 11 is measured based on the output pulse of the encoder 19 (S504). If the measured cycle matches the specified cycle (S505), the speed determination is OK (S506). When the speed determination is OK, an image formation start signal is generated (S507), and image formation is started (S508).
[0028]
(Second embodiment)
FIG. 6 is a diagram further illustrating the features of the second embodiment of the present invention. The same functions and components as those of the first embodiment of the present invention shown in FIG. Omitted.
[0029]
In FIG. 6, reference numeral 29 denotes an image quality mode selection unit, which can select at least two modes, for example, a high image quality mode and a low image quality mode. The selection of the image quality mode can be instructed from the host computer 28. Reference numeral 30 denotes a panel operation unit mounted on the image forming apparatus, which allows a user to make various settings. Here, the configuration is such that the user can select the image quality mode from the panel operation unit 30 as well.
[0030]
Next, the operation of the image forming apparatus having the above configuration will be described with reference to FIG.
When receiving the image data from the host computer 28, the CPU 26 first sends a drive start signal to the motor 25, which is the drive source of the conveyor belt 11. The motor 25 is controlled to rotate at a predetermined speed after a certain period of time after receiving the motor drive start signal. At the same time as the driving of the motor 25, the output monitor of the encoder 19 is started. The speed detector 22 sequentially checks the cycle of the pulse output of the encoder 19. The speed determination unit 23 compares the pulse cycle of the encoder 19 with a predetermined conveyance belt cycle optimal for image formation, and determines the speed of the conveyance belt 11. As described in detail in the first embodiment of the present invention, the method of determining the speed includes a method of determining the speed based on the number of coincidences of the pulse periods within a certain period, and a method of calculating the average value of the pulse periods within a certain period. is there. Also, a predetermined period of the transport belt is stored in the memory 31 and is set at various speeds (for example, when an image is formed on a print medium such as OHP (overhead projector) paper, a lower speed is set than that of plain paper. ) Is stored.
[0031]
Here, the image quality mode selection unit 29 checks what the image quality mode specified by the host computer 28 is. In the host computer 28, an image quality mode is selected on a screen by a so-called printer driver. As another means, the image quality mode can be directly selected from the panel operation unit 30 mounted on the image forming apparatus.
[0032]
When the selected image quality mode is the high image quality mode, the CPU 26 does not start image formation until the speed determination unit 23 confirms the output of the speed OK. When the output of the speed OK is confirmed by the speed determination unit 23, the image formation start signal generation unit 24 generates an image formation start signal, and starts the above-described series of image formation processes.
[0033]
If the selected image quality mode is the low image quality mode, the CPU 26 ignores the output of the speed determination unit 23 and the image formation start signal generation unit 24 outputs the image formation start signal Is generated, and the image forming process is started.
[0034]
After the image formation start signal is generated by the image formation start signal generation unit 24, the print medium 13 stored in the paper supply unit 12 of FIG. 1 is transported to the image formation unit. The transported print medium 13 is attracted to the transport belt 11 and transported to the front edge of the BK developing cartridge 9. Here, the toner image formed on the photoconductor 4 of the BK developing cartridge 9 is transferred onto the print medium 13. From here, the toner images on the photoconductors of the developing cartridges 8, 7, and 6 are sequentially transferred onto the print medium 13 according to the conveyance of the conveyance belt 11, and a full-color image is formed.
[0035]
If the image data is in the low image quality mode, the print medium 13 stored in the sheet feeding unit 12 is transported to the image forming unit before the generation of the image formation start signal is performed. The transported print medium is attracted to the transport belt 11 and transported to the front edge of the BK developing cartridge. Thereafter, the toner images of the respective colors are superimposed on the print medium and transported to the fixing device 14 according to the transport belt 11. The toner image is fixed on the print medium 13 and discharged.
[0036]
The above control operation will be further described with reference to the flowchart of FIG.
When image data is received from the host computer 28 (S701), the CPU 26 determines whether the image quality mode information previously received from the host computer 28 is a high image quality mode or a low image quality mode. (S702). Similarly, it is determined whether the image quality mode information selected by the panel operation unit 30 is the high image quality mode or the low image quality mode (S703).
[0037]
If the selected image quality mode is the low image quality mode, the CPU 26 generates an image formation start signal without waiting for the stabilization of the transport belt 11 (S708), and starts image formation (S709).
[0038]
If the selected mode is the high image quality mode, the CPU 26 starts detecting the speed of the conveyor belt 11 (S704). The cycle of the conveyor belt 11 is measured (S705), and if the measured cycle matches the specified cycle (S706), the speed determination is OK (S707). When the speed determination is OK, an image formation start signal is generated (S708), and image formation is started (S709).
[0039]
(Other embodiments)
As described above, the embodiments of the present invention have been described in detail. However, the configurations of the first embodiment and the second embodiment of the present invention described above may be combined. That is, the step of S502 of FIG. 5 may be inserted between the steps of S701 and S702 of FIG. 7, and when the image data is a monochrome image, the processing may shift from S502 to S703.
[0040]
Further, in each of the embodiments of the present invention described above, the generation of the image formation start signal is controlled according to the print mode. However, regardless of the print mode, the speed determination unit waits for the determination of the speed OK and the image formation start signal. Is included in the embodiment of the present invention.
[0041]
In the configuration of FIG. 1 according to an embodiment of the present invention, a plurality of developing devices are juxtaposed, toner images of respective colors are formed on respective image carriers in the developing devices, and the toner images are formed into an endless belt shape. Although the image forming apparatus that directly transfers the image onto the print medium conveyed by the conveying belt has been illustrated, the present invention is not limited to this, and a plurality of developing devices are juxtaposed, and each color is formed on each image carrier in these developing devices. The present invention can be similarly applied to an image forming apparatus which forms a toner image of the same type, transfers the toner image to an endless belt-shaped intermediate transfer body, and re-transfers it to a print medium.
[0042]
Further, the present invention may be applied to a computer system including a plurality of devices, or may be applied to a printing device including a single device.
[0043]
According to the present invention, a software program (in this embodiment, a program corresponding to the flowcharts shown in FIGS. 5 and 7) for realizing the functions of the above-described embodiments is supplied to a system or apparatus directly or remotely. This is also achieved by a computer of the system or apparatus reading and executing the supplied program. In that case, the form need not be a program as long as it has the function of the program.
[0044]
Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. That is, the claims of the present invention include the computer program itself for realizing the functional processing of the present invention.
[0045]
In that case, the program may be in any form, such as an object code, a program executed by an interpreter, and script data supplied to an OS (Operating System), as long as the program has the function of the program.
[0046]
As a recording medium for supplying the program, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card ( IC memory card), ROM, DVD (DVD-ROM, DVD-R) and the like.
[0047]
In addition, as a method of supplying the program, a browser of a client computer is used to connect to a homepage on the Internet, and from this homepage, the computer program itself of the present invention or a compressed file including an automatic installation function is downloaded to a recording medium such as a hard disk. Can also be supplied. Further, the present invention can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. In other words, a WWW server that allows a user to download a program file for realizing the functional processing of the present invention on a computer is also included in the claims of the present invention.
[0048]
In addition, the program of the present invention is encrypted, stored in a recording medium such as a CD-ROM, distributed to users, and downloaded to a user who satisfies predetermined conditions by downloading key information for decrypting from a homepage via the Internet. The present invention can also be realized by executing the encrypted program by using the key information and installing the program on a computer.
[0049]
The functions of the above-described embodiments of the present invention are implemented when the computer executes the read program, and the OS or the like running on the computer executes actual processing based on the instructions of the program. The functions of the above-described embodiments of the present invention can also be realized by performing part or all of the processing described above.
[0050]
Further, after the program read from the recording medium is written into the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, the function expansion board or the A CPU or the like provided in the function expansion unit performs part or all of actual processing, and the functions of the above-described embodiments of the present invention are also realized by the processing.
[0051]
[Embodiment 1]
A plurality of developing devices are juxtaposed, a toner image of each color is formed on each image carrier in these developing devices, the toner image is transferred to an endless belt-shaped intermediate transfer member, and re-transferred to a print medium, or In an image forming apparatus that directly transfers onto a print medium conveyed by an endless belt-shaped conveyance belt, a belt speed detection unit that detects a speed of the endless belt-shaped intermediate transfer body or the endless belt-shaped conveyance belt, A belt speed determining unit that determines that the speed of the intermediate transfer body or the transport belt is stabilized based on a detection output of the belt speed detecting unit, and an image forming start timing according to the determination output of the belt speed determining unit. An image forming apparatus comprising: an image forming start signal generating unit that generates the image forming start signal.
[0052]
[Embodiment 2]
The image forming apparatus according to the first embodiment further includes an image determination unit configured to determine whether the image data is a color image or a monochrome image based on the image data on which the image is to be formed. Means for determining a priority of a determination output of the belt speed determination means with respect to a timing of generating the image formation start signal in accordance with a determination result of the image determination means.
[0053]
[Embodiment 3]
The image forming apparatus according to the first or second embodiment further includes an image quality selection mode selection unit that can select an image quality after image formation, and wherein the image formation start signal generation unit is an image quality selection mode selection unit. An image forming apparatus according to claim 1, wherein a priority of a determination output of said belt speed determination means relating to a timing of generating said image formation start signal is determined according to a selected image quality mode.
[0054]
[Embodiment 4]
In the image forming apparatus according to the second embodiment, when a full-color image is confirmed by the image determination unit, the image formation start signal generation unit determines the intermediate transfer body or the An image forming apparatus, wherein the image forming start signal is not generated until it is confirmed that the speed of the conveyor belt is stable.
[0055]
[Embodiment 5]
In the image forming apparatus according to the second embodiment, when a monochrome image is confirmed by the image determination unit, the image formation start signal generation unit determines the intermediate transfer member or the intermediate transfer member based on a determination output of the belt speed determination unit. An image forming apparatus, wherein the image forming start signal is generated when a predetermined time has elapsed even if it is not confirmed that the speed of the conveyor belt is stable.
[0056]
[Embodiment 6]
In the image forming apparatus according to the third embodiment, when a high image quality mode is selected by the image quality selection mode selection unit, the image formation start signal generation unit performs the intermediate transfer based on a determination output of the belt speed determination unit. An image forming apparatus, wherein the image formation start signal is not generated until it is confirmed that the speed of the body or the conveyor belt is stabilized.
[0057]
[Embodiment 7]
In the image forming apparatus according to the third embodiment, when a low image quality mode is selected by the image quality selection mode selection unit, the image formation start signal generation unit determines the intermediate transfer based on a determination output of the belt speed determination unit. An image forming apparatus, wherein the image forming start signal is generated when a predetermined time has elapsed even if it is not confirmed that the speed of the body or the conveyor belt is stable.
[0058]
[Embodiment 8]
The image forming apparatus according to the third embodiment, wherein a user can arbitrarily select a print image quality through the image quality selection mode selection unit.
[0059]
[Embodiment 9]
In the image forming apparatus according to the first embodiment, the belt speed detecting unit that detects a speed of the transport belt is configured to output a speed of the transport belt based on an output of an encoder attached to a roller that is driven by driving the transport belt. An image forming apparatus characterized by detecting the following.
[0060]
[Embodiment 10]
In the image forming apparatus according to the first embodiment, the belt speed detecting unit that detects a speed of the transport belt reads at least one or more detection marks formed on the transport belt to transfer the transport belt. An image forming apparatus for detecting a speed of a belt.
[0061]
[Embodiment 11]
In the image forming apparatus according to the first embodiment, the belt speed determination unit compares the detection output of the belt speed detection unit with a predetermined period set in advance to thereby determine the speed of the intermediate transfer body or the conveyance belt. An image forming apparatus that determines that the image is stable.
[0062]
[Embodiment 12]
A plurality of developing devices are juxtaposed, a toner image of each color is formed on each image carrier in these developing devices, the toner images are transferred to an endless belt-shaped intermediate transfer member, and re-transferred to a print medium, or In an image forming method of an image forming apparatus for directly transferring onto a print medium conveyed by an endless belt-shaped conveyance belt, a belt speed for detecting a speed of the endless belt-shaped intermediate transfer body or the endless belt-shaped conveyance belt A detecting step, a belt speed determining step for determining that the speed of the intermediate transfer member or the transport belt is stabilized based on the output detected in the belt speed detecting step, and a determination output in the belt speed determining step. An image forming start signal generating step of generating an image forming start timing by using the image forming method.
[0063]
Embodiment 13
A plurality of developing devices are juxtaposed, a toner image of each color is formed on each image carrier in these developing devices, the toner image is transferred to an endless belt-shaped intermediate transfer member, and re-transferred to a print medium, or A computer-readable storage medium storing a control program for controlling an image forming apparatus that directly transfers a print image onto a print medium conveyed by an endless belt-shaped conveyance belt, wherein the control program is an endless A belt speed detecting step for detecting the speed of the belt-shaped intermediate transfer body or the endless belt-shaped transport belt; and a speed of the intermediate transfer body or the transport belt based on an output detected in the belt speed detecting step. A belt speed determining step of determining that the image forming has been performed, and an image forming start timing according to the determination output in the belt speed determining step. Characterized in that to execute the image formation start signal generating step of forming on a computer storage medium storing a control program.
[0064]
[Embodiment 14]
A plurality of developing devices are juxtaposed, a toner image of each color is formed on each image carrier in these developing devices, the toner image is transferred to an endless belt-shaped intermediate transfer member, and re-transferred to a print medium, or A computer-executable control program for controlling an image forming apparatus that directly transfers onto a print medium conveyed by an endless belt-shaped conveyance belt, the control program comprising: A belt speed detecting step for detecting a speed of the transfer belt, which is a transfer body or an endless belt, and determining that the speed of the intermediate transfer body or the transfer belt is stabilized based on an output detected in the belt speed detection step. A belt speed determination step, and an image formation start signal for generating an image formation start timing according to the determination output in the belt speed determination step Control program characterized and a growth step.
[0065]
【The invention's effect】
As described above, according to the present invention, image formation starts at the time when the speed of the belt itself is stabilized at the time of driving the belt with respect to the change in the circumferential length of the conveyance belt with time and the change in the tension, so that the belt conveyance is unstable. The deterioration of the color misregistration of the toner images of a plurality of colors is eliminated.
[0066]
Further, in the present invention, it is determined whether or not the image data is monochrome, and the image forming speed is prioritized when printing a monochrome image, or the image forming speed is prioritized when the image quality is low, so that the printing mode can be set during image forming. Optimum control of the transport belt can be performed accordingly.
[0067]
Further, in the present invention, the high image quality mode and the low image quality mode are provided, and the mode can be selected by the user, so that it is possible to control the transport belt optimally according to the mode desired by the user. Therefore, according to the present invention, the selectivity of giving priority to high image quality and giving priority to printing speed is expanded, and it becomes possible to select a mode desired by the user.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic front vertical cross-sectional structure of a printer as a representative example of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a configuration of a transport belt and a drive system of the image forming apparatus according to the first exemplary embodiment of the present invention.
FIG. 3 is a block diagram illustrating a circuit configuration for controlling a conveyance belt of an image forming system according to the first embodiment of the present invention.
FIG. 4 is a conceptual diagram illustrating a method for detecting the speed of the conveyor belt according to the first embodiment of the present invention.
FIG. 5 is a flowchart illustrating a processing procedure of a control system that controls the image forming apparatus according to the first embodiment of the present invention.
FIG. 6 is a block diagram illustrating a circuit configuration of a control system that controls a conveyance belt of an image forming system according to a second embodiment of the present invention.
FIG. 7 is a flowchart illustrating a processing procedure of a control system that controls an image forming apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
1 Scanner unit
2 rotating polygon mirror
3 cartridges
4 Photoconductor
5 Developing sleeve
6 Y (yellow) developing cartridge
7 M (magenta) developing cartridge
8 C (cyan) developing cartridge
9 BK (black) developing cartridge
10 Transfer roller
11 Conveyor belt
12 Paper feed unit
13 Print media
14 Fixing unit
15 Fixing roller
16 Heater roller
17 tension roller
18 driven roller
19 Encoder
20 Code Wheel
21 Photo interrupter
22 Speed detector
23 Speed judgment unit
24 Image formation signal generation unit
25 motor
26 CPU
27 Image Data Color Discriminator
28 Host computer
29 Image quality mode selector
30 Panel operation unit
31 memory

Claims (1)

A plurality of developing devices are juxtaposed, a toner image of each color is formed on each image carrier in these developing devices, the toner images are transferred to an endless belt-shaped intermediate transfer member, and re-transferred to a print medium, or In an image forming apparatus which directly transfers onto a print medium conveyed by an endless belt-shaped conveyance belt,
Belt speed detecting means for detecting the speed of the endless belt-shaped intermediate transfer member or the endless belt-shaped transport belt,
Belt speed determination means for determining that the speed of the intermediate transfer member or the transport belt is stabilized based on the detection output of the belt speed detection means,
An image forming apparatus comprising: an image forming start signal generating unit that generates an image forming start timing according to a determination output of the belt speed determining unit.

Images