JPH11258886A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain both subjects to prevent the life of an image forming unit from being uselessly shortened and to prevent the reduction of the productivity, even though both subjects are antithetical, as for a tandem type image forming device. SOLUTION: As for the image forming device, the image is formed under a color printing mode using plural image carriers, or a monochromatic printing mode using one image carrier. In this case, the device is provided with an inputting means for inputting whether a life priority mode is selected, or a productivity priority mode is selected, a detecting means for detecting whether an image to be formed is a color image or a monochromatic black image, and an image forming means (S35), as for the image forming means, in the case the life priority mode is selected (S33: No), the image is formed under the color printing mode when the image to be formed is a color one (S34→S36) and the image is formed under the monochromatic printing mode when the image to be formed is the monochromatic black one (S34→S35), and in the case the productivity priority mode is selected (S31: Yes), the image is formed under the color printing mode (S35).

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 such as a printer, a copying machine and a facsimile capable of forming a color image, and more particularly to a technique for switching an image forming mode between a color image formation and a monochrome image formation. About.

[0002]

2. Description of the Related Art In recent years, with the explosive spread of personal computers and digital cameras, opportunities for outputting and copying color documents, color photographs, and the like have increased rapidly. Further, since it is preferable that the speed at which an image is formed by a printer, a copying machine or the like is slightly higher, it is desired to develop a full-color image forming apparatus having a higher speed at which an image is formed.

A tandem type full-color image forming apparatus has a relatively high image forming speed.
It is becoming mainstream now. This is achieved by arranging a plurality of image forming units including a photoreceptor drum and a transfer unit along a transport belt that transports a transfer material such as transfer paper, and forming each color toner image with each image forming unit. The image is transferred by being superimposed on a transfer material, and a full-color image can be formed with one pass of paper.

[0004] When an image of only black is formed using such a tandem-type image forming apparatus, an image forming unit for forming a toner image other than black does not contribute to image formation. Also, in general, the photosensitive drum and the cleaner member of the image forming unit are always in direct contact with each other, so that the photosensitive drum is worn only by the rotation of the photosensitive drum, and the rotation time of the photosensitive drum affects the life of the image forming unit. It is not an exaggeration to say that they are heavily involved.

Therefore, it is desirable to stop the rotation of the photosensitive drum of the image forming unit which does not contribute to image formation. However, in the conventional tandem-type image forming apparatus, the photosensitive drums of all the image forming units are always in contact with the transport belt, and all the photosensitive drums are driven by the transport belt to smoothly drive the transport belt. , The rotation of the photosensitive drum cannot be selectively stopped.

Therefore, when an image consisting only of black is formed, the life of the image forming unit that does not contribute to image formation is shortened unnecessarily, and the amount of toner other than black is unnecessarily reduced. Conventional techniques for solving such problems include:
JP-A-3-288173, JP-A-6-10277
No. 6 and JP-A-6-258914. According to these techniques, when a color image is formed, an operator selects a mode (hereinafter, referred to as a “color print mode”) in which an operator can form both a color image and a black-only image in advance. When forming an image by the method and forming an image of only black,
By selecting a mode for forming an image of only black (hereinafter, referred to as “single color print mode”), the photosensitive drum of the image forming unit for forming a toner image other than black is separated from the conveyance belt, and the separated photosensitive drum is separated. The rotation of the body drum is stopped, and an image is formed only by the image forming unit that forms a black toner image.

[0007]

However, in the above-described conventional image forming apparatus, the operator must determine whether the image to be formed is a color image or a black-only image, which is troublesome. In the case of continuously forming a color image to be formed and a black-only image continuously, the only option is to select a color print mode. Therefore, when forming a black-only image, the monochrome print mode cannot be implemented.

Therefore, if the image to be formed is detected as a color image or a black image only, and the print mode is automatically switched accordingly, the image can be formed properly, and The life of the image forming unit that does not contribute is not shortened unnecessarily. However, on the other hand, in the case where a mixed color image and an image of only black are continuously formed, when the print mode is automatically switched, frequent switching occurs frequently. In comparison, the processing time is lengthened by an amount proportional to the number of times of switching, causing a drop in productivity.

[0009] It is a contradictory problem that the life of the image forming unit is not unnecessarily shortened and that the productivity is not reduced, and it is urgently necessary to achieve both of these at the site of use. In view of the above, the present invention has been made to solve the problem by focusing on the fact that it is possible to judge whether to give priority to not shortening the life of the image forming unit unnecessarily or not reducing the productivity, depending on the situation at the time of use. It is a thing.

[0010]

In order to solve the above problems, the present invention provides two image forming modes, an image forming mode using a plurality of image carriers and an image forming mode using one image carrier. An image forming apparatus for forming an image by switching between a first mode and a second mode, and a detecting unit for detecting whether an image to be formed is a color image or a monochrome image. In the first mode, the frequency of switching between the two image forming modes according to whether the image to be formed is a color image or a monochromatic image and in the second mode, the frequency of switching between the two image forming modes is as follows in the first mode. And switching means for switching.

Further, the present invention provides a first image forming mode using a plurality of image carriers and a second image forming mode using one image carrier.
An image forming apparatus for forming an image in one of the two image forming modes, an input unit for inputting a first mode or a second mode, and at least a first mode Detecting means for detecting whether the image to be formed is a color image or a monochrome image in the case of the first mode, and forming and forming an image in the first image forming state when the image to be formed is a color image in the first mode The image forming apparatus further includes a forming unit that forms an image in the second image forming state when the image is a monochromatic image, and forms an image in the first image forming state when the image is in the second mode.

The detecting means further detects whether the image to be formed is a color image or a monochrome image even in the second mode, and the forming means determines whether the image to be formed is the one in the first mode. When a color image is formed, an image is formed in the first image forming mode. When the image to be formed is a monochromatic image, an image is formed in the second image forming mode. In the second mode, when the image to be formed is a color image. An image is formed in the first image forming mode, and when the image to be formed is a monochromatic image, the image is formed in one of the image forming modes depending on whether the previously formed image is a color image or a monochromatic image. It can also be.

Further, the image forming apparatus stands by in one of a first image forming mode and a second image forming mode, and the detecting means further includes a second mode and a second image forming mode. Even when the image forming apparatus is on standby, the image forming apparatus detects whether the image to be formed is a color image or a monochrome image.
In the mode, when the image to be formed is a color image, an image is formed in the first image forming mode, and when the image to be formed is a monochrome image, the image is formed in the second image forming mode. When waiting in the image forming mode of
When the image is formed in the second image forming mode and the image forming apparatus is in the second mode and in the second image forming mode, the image is formed in the second image forming mode when the image to be formed is a monochromatic image. When the image to be formed is a color image, the image may be formed in the first image forming mode.

Further, the image forming apparatus may further comprise an automatic document reading means for automatically transferring a document placed at a predetermined position and forming an image to be read while forming the image to be read. Use determining means for determining whether or not the current mode is the second mode when the use determining means determines to use.

Further, the image forming apparatus further comprises: a document reading means for reading a document placed at the document reading position as an image to be formed; and a use determining means for determining whether to use the document reading means. Wherein the input means inputs the current mode as the first mode when the use determining means determines that the first mode is to be used.

Further, the image forming apparatus further comprises: acquiring means for acquiring image information from the outside to be information of an image to be formed, and determining whether or not the acquiring means has acquired the image information from the outside. The input means may input the current mode as the first mode when the input source determining means determines that the current mode is the first mode.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described below using a tandem type digital color copying machine (hereinafter simply referred to as "copying machine") as an example. <Structure> FIG. 1 is a diagram showing the overall structure of a digital color copying machine according to the present embodiment.

The copying machine shown in FIG. 1 has an automatic document feeder 10 for automatically feeding a document placed at a predetermined position automatically.
An image reader unit 20 reads an image of a conveyed document, and a printer unit 40 prints and reproduces the image read by the image reader unit 20 on a recording sheet such as copy paper. The automatic document feeder 10 includes a document feed tray 11 on which a document is set, and a document
1 includes a paper feed roller 12, a separation roller 13 for assisting in document removal, a separation pad 14, a document transport belt 15 for transporting the document, and a document discharge tray 16 for discharging the read document.

The image reader unit 20 includes a platen glass 21 on which a document is placed when reading, a scanner 22 for irradiating the document and outputting reflected light, mirrors 26 and 27 for guiding the reflected light to a condenser lens 28, and a mirror 26. Slider 25 that holds and operates 27, condenser lens 2 that collects reflected light
8. The light condensed by the condenser lens 28 is converted into red (R), green (G), and blue (B) (hereinafter simply referred to as “R”,
A charge-coupled device (Charge-Coupled-De) that converts an electrical signal for each of the “G” and “B” components
services, hereinafter "CCD". 29), a white plate 30 for shading correction, and a scanner motor M1 for driving the scanner 22 and the slider 25.

Here, the shading correction is to eliminate the irradiation unevenness of the exposure lamp 23 and the sensitivity unevenness of the CCD 29, and the white light 30 placed on the end of the platen glass 21 at the time of the pre-scan is actually applied to the exposure lamp 23. Is reflected by the CCD 29, and the reflected light is converted into an electric signal by the CCD 29, and is compared with a standard value stored in advance to calculate a correction value. The electric signal at the time of scanning is corrected by the correction value.

The scanner 22 includes an exposure lamp 23 for irradiating a document and a mirror 24 for guiding the reflected light to a mirror 26. An operation panel 31 is provided on the front surface of the image reader unit 20, and accepts operations from the operator and various settings, and displays the setting status and the like. Printer section 40
Is a device for forming an image on a recording sheet by using a well-known electrophotographic technique. An optical system 50 for optically forming an image, an image processing system 60 for forming an image on a recording sheet, and a CCD 29 are provided. Control unit 10 that controls optical system 50, image processing system 60, and the like based on the converted electric signal.
0, a fixing unit 64 for thermally fixing the formed image and a paper feed system 70 for conveying the recording sheet.

The control unit 100 converts the electric signals for each of the R, G, and B components into cyan (C), magenta (M), yellow (Y), and black (K) (hereinafter simply referred to as “C”, respectively).
"M", "Y", and "K") are converted into density data of each reproduced color, and are converted into drive signals of laser diodes, respectively, and the laser diodes for each reproduced color are optically modulated and driven. Then, it is determined whether the corresponding original is a color image or a black-only image.

Further, the entire apparatus is controlled, the print mode is determined, and switching is controlled. Here,
It is assumed that C, M, Y, and K are added as subscripts to the numbers of the components related to each of the reproduced colors C, M, Y, and K, respectively. The optical system 50 includes a laser diode (not shown) provided for each image forming unit, and a polygon mirror 5 for deflecting laser light emitted from each laser diode.
1. fθ lenses 52C and 52M for condensing each laser beam,
52Y, 52K and a folding mirror for guiding each of the collected laser beams to the corresponding image forming unit.

The paper feed system 70 feeds paper feed cassettes 71 to 74 on which recording sheets are set, pickup rollers 75 to 78 for taking out the recording sheets from each paper feed cassette, recording sheet detection sensors SE1 to SE6, and conveys the recording sheets. It includes a timing roller 79, a timing clutch 84 for controlling the rotational drive of the timing roller 79, and a recording sheet discharge tray 65 from which printed recording sheets are discharged.

The recording sheet detection sensors SE1 to SE6 are:
These sensors are provided to detect a recording sheet and detect a paper jam (hereinafter, referred to as “jam”) or the like. Each of the sensors detects a recording sheet conveyed to each conveyance path, and outputs a detection signal to the control unit 100. To send to. The control unit 100
If a recording sheet to be detected is not detected after a predetermined time has elapsed, it is determined that a jam has occurred.

FIG. 2 is a diagram showing a detailed configuration of the image processing system 60. The image processing system 60 shown in FIG. 2 includes image forming units 61C, 61M, 61Y, 61K and a transfer unit 82. Here, it is assumed that the recording sheet is conveyed from right to left in each drawing.
Hereinafter, the right side of each figure is referred to as an upstream side, and the left side is referred to as a downstream side.

The image forming unit 61C includes a photosensitive drum 61
1C, a charger 612C, a developing device 613C, and a cleaner 614C. Similarly, the image forming unit 61M
Represents a photosensitive drum 611M, a charging charger 612M,
Developing unit 613M, cleaner 614M and transfer blade 6
2M, the image forming unit 61Y includes a photosensitive drum 61
1Y, a charging charger 612Y, a developing device 613Y, a cleaner 614Y, and a transfer blade 62Y. The image forming unit 61K includes a photosensitive drum 611K, a charging charger 612K, a developing device 613K, and a cleaner 614K.

Photosensitive drums 611C, 611M, 611
For Y and 611K, an electrostatic latent image is written by the laser light emitted from the optical system 50 to form a toner image, and the toner image is transferred to a recording sheet. Charger 61
2C, 612M, 612Y, and 612K are arranged around each photoconductor drum and charge each photoconductor drum before an electrostatic latent image is written.

Developing units 613C, 613M, 613Y, 6
13K forms a toner image from the electrostatic latent image and visualizes it. Cleaner 614C, 614M, 614Y, 614K
Removes toner remaining on each photosensitive drum after transfer. The transfer unit 82 includes a transport belt 81, a driving roller 822, an auxiliary roller 823, a driven roller 824, a tension roller 825, a cleaner roller 826, a tension spring 828, a belt cleaner 83, a transfer blade 62C, 62M, 62Y, 62K, a spring 63C,
63M, 63Y, 63K, spring 827, plate cam 8
291, a rotating shaft 8292, a swing frame 829, and a guide 80.

The transport belt 81 is stretched by a drive roller 822, an auxiliary roller 823, a driven roller 824, a tension roller 825, and a cleaner roller 826, and transports a recording sheet. The driving roller 822 is rotated by driving a stepping motor (not shown), and
1 is driven.

The auxiliary roller 823, the driven roller 824, the tension roller 825, and the cleaner roller 826 are driven as the transport belt 81 is driven. The tension spring 828 urges the tension roller 825 outward to apply a constant tension to the transport belt 81. The cleaner roller 826 and the belt cleaner 83 sandwich the transport belt 81 between them, and remove residual toner, paper dust, and the like attached to the surface of the transport belt 81.

The transfer blades 62C, 62M, 62Y and 62K are respectively disposed at positions facing the respective photosensitive drums with the conveyance belt 81 interposed therebetween, and apply a toner image formed on each photosensitive drum by electrostatic force to a recording sheet. A voltage having a potential opposite to that of the charge of the toner particles is applied. The springs 63C, 63M, 63Y and 63K are provided with respective transfer blades 62C, 62M, 6
2Y and 62K are urged upward, and the tips of the transfer blades urged upward press the transfer belt 81 against the photosensitive drums facing each other.

In this way, the transfer belt 81 is pressed against the photosensitive drum to prevent transfer unevenness in the main scanning direction. The spring 827 is
The swing frame 829 is urged upward. Plate cam 8291
Is rotated by a driving device (not shown) such as a motor around a rotating shaft 8292, and a lower peripheral surface thereof is
29, the swing frame 829 is pressed down.

The swing frame 829 includes a driven roller 824.
Can be moved up and down with the rotation axis of the plate cam 8 as a fulcrum.
Since it is pressed down by the lower peripheral surface of 291, it is vertically driven to swing by the rotation of the plate cam 8291. A driving roller 822, a stepping motor (not shown) for rotating the driving roller 822, transfer blades 62C, 62M, 62Y, springs 63C, 6
3M and 63Y are attached, all of which swing together with the swing frame 829. Here, these swinging portions are collectively referred to as a swinging unit 821.

A notch 8293 is provided on the side surface of the swing frame 829 so that the swing unit 821 does not come into contact with the rotating shaft 8292 even if it swings up and down. In addition, in order to control the swing unit 821 to stop at predetermined upper and lower positions, the rotation position of the plate cam 8291 or the height of the swing frame 829 is determined by a sensor (a photo sensor, a magnetic sensor, a sound wave sensor, A position detection sensor such as a microswitch, which is detected by a not-shown).

The guide 80 swings following the swing of the swing unit 821 about the rotation axis of the timing roller 79 as a fulcrum, and transfers the recording sheet from the timing roller 79 to the transport belt irrespective of the position of the swing unit 821. Guide to 81. The auxiliary roller 823 and the driven roller 82
4. Cleaner roller 826, tension spring 82
8, the belt cleaner 83, the transfer blade 62K, the spring 63K, and the rotating shaft 8292 are connected to the image forming unit 61C,
It is attached to the same main body frame together with 61M, 61Y and 61K, and their positional relationship does not change even if the swing frame 829 swings.

FIG. 3 is a diagram showing a detailed configuration of the image processing system 60, and shows a state where the swing unit 821 is stopped at a predetermined lower position. When an image is formed in the color print mode, as shown in FIG.
21 stops at the predetermined upper position, and the transport belt 81 is kept horizontal, so that the transport belt 81 is pressed against all the photosensitive drums 611C, 611M, 611Y, and 611K. Therefore, all the photosensitive drums are driven to form a color image. However, even when only a black image is formed, a photosensitive drum which is not involved in image formation is required to smoothly drive the transport belt 81. Drive.

On the other hand, when an image is formed in the single-color print mode, the swing unit 821 stops at a predetermined lower position as shown in FIG. 3, and the transport belt 81 upstream of the auxiliary roller 823 tilts downward. Therefore, the conveyor belt 81 is pressed against the photosensitive drum 611K and is pressed against the photosensitive drums 611C and 611C.
11M and 611Y. Accordingly, the photosensitive drums 611C, 611M, and 6 that form toner images other than black
The driving of 11Y is stopped, and only the photosensitive drum 611K for forming a black toner image is driven to form a black-only image.

FIG. 4 is a diagram showing a detailed configuration of the control unit 100. The control unit 100 shown in FIG. 4 includes an image signal processing unit 102, a document discrimination unit 103, an image memory 104, a laser diode driving unit 105, a ROM 106, a CPU 101
And a RAM 107. Image signal processing unit 102
Performs analog / digital conversion and shading correction on the electrical signals for each of the R, G, and B components transmitted from the CCD 29 of the image reader unit 20, and sends the signals to the document discriminating unit 103 in page units. The data is converted into density data of each of the reproduced colors C, M, Y, and K by the correction processing and transmitted to the image memory 104.

The document discriminating unit 103 includes the image signal processing unit 10
Based on the electric signal subjected to the analog / digital conversion and the shading correction by 2, it is determined whether the corresponding original is a color image or a black-only image, and the result is sent to the CPU 101 as color information. The image memory 104 stores the density data of each reproduction color converted by the image signal processing unit 102, and when the CPU 101 requests reading of a certain storage position, the density data of each reproduction color at the storage position requested to be read. To the laser diode driver 10
5

The laser diode drive unit 105 converts the density data of each reproduced color sent from the image memory 104 into a drive signal for the laser diode, and drives each laser diode for each reproduced color with light modulation. ROM1
Reference numeral 06 stores a program necessary for control. CPU1
01, based on a program stored in the ROM 106, accepts operations and various settings by the operator from the operation panel 31, displays the setting status, etc.
It controls the operation of each unit such as the image reader unit 20, the printer unit 40, etc., monitors jams, and controls the entire apparatus. The document number is also transmitted to the RAM 107 in association with the number of pages of the document, the storage position of the density data of each reproduced color (the address of the image memory 104), and the color information determined by the document determination unit 103. Further, reading of the storage position of the density data of each reproduction color corresponding to the image to be formed is performed by the image memory 104.
Request to. The print mode is determined based on each mode selected by the operator and the color information transmitted by the document determination unit 103, and switching of the print mode is controlled.

The RAM 107 is a work area when the program is executed, and includes the number of pages associated with the CPU 101,
The storage position and color information are stored in an internal management table.
FIG. 5 is a diagram showing the operation panel 31. Operation panel 3
Reference numeral 1 is provided on the front surface of the image reader unit 20, receives operations from an operator and various settings, and displays the setting status and the like.

The operation panel 31 has a number input section 311 for inputting the number of copies and the like, a number display section 312 for displaying the number of copies and the like, a print start key 313 for instructing to start copying, and a print stop for instructing to stop copying. Key 314, color mode selection key 315 for selecting a color mode, black and white mode selection key 31 for selecting a black and white mode
6. A productivity priority mode selection key 317 for selecting the productivity priority mode, a life priority mode selection key 318 for selecting the life priority mode, and selection indicators 319 for indicating which mode is selected. .

In this case, the life priority mode is automatically selected when the power is turned on, when the power is reset, when a predetermined time elapses, or the like. <Operation> The document set on the document feed tray 11 is transported by the document transport belt 15 to a predetermined document reading position on the platen glass 21 and scanned by the scanner 22 of the image reader unit 20 and then again transported to the document transport belt. The document 15 is conveyed and discharged to a document discharge tray 16.

When the automatic document feeder 10 conveys the document to the document reading position on the platen glass 21, the scanner 22
Scans the original while moving in the direction of the arrow in FIG. 1 by driving the scanner motor M1. Slider 2 at the same time
The mirrors 26 and 27 held as a pair at 5 move in the same direction at half the speed of the scanner 22 by driving the scanner motor M1. By these operations, the optical path length from the document surface to the condenser lens 28 is maintained at a constant length.

The reflected light output by irradiating the original with the scanner 22 is guided to a condenser lens 28 by mirrors 26 and 27, condensed by a condenser lens 28, and is charged by a CCD 29 for each of R, G, and B components. The signal is photoelectrically converted into a signal and the control unit 1
00 is sent to the image signal processing unit 102. CPU10
1 requests the reading of the storage position of the density data of each reproduction color corresponding to the image to be formed, the image memory 104 sends out the density data of each reproduction color at the storage position requested to be read, and drives the laser diode. The unit 105 converts the laser diodes into drive signals for the respective laser diodes, and drives the laser diodes for each of the reproduced colors with light modulation to emit laser light.

The laser light emitted from each laser diode is reflected by the mirror surface of a polygon mirror 51 rotated by driving a polygon motor (not shown), and is condensed by fθ lenses 52C, 52M, 52Y and 52K. Are guided to the corresponding image forming units by the folding mirrors, and the photosensitive drums 611C, 611M, 611Y, 6
An electrostatic latent image is written by exposing and scanning the surface of 11K in the main scanning direction. This electrostatic latent image is developed by a developing device 613C,
Each toner image is formed by 613M, 613Y, and 613K to be visualized and sequentially transferred to the same recording sheet.

The recording sheet is fed from the selected one of the paper cassettes 71 to 74 by the corresponding pickup rollers 75 to 78, and is fed by the timing roller 79 and the transport belt 81 to the photosensitive drum 611C.
611M, 611Y and 611K are sequentially conveyed to the transfer positions, and the transfer blades 62C and 62C are transferred at each transfer position.
M, 62Y, and 62K electrostatic photoconductive drums 611
The toner images formed on C, 611M, 611Y, and 611K are sequentially transferred to the recording sheet, are thermally fixed in the fixing unit 64, and are discharged to the recording sheet discharge tray 65.

At this time, the image forming operation on each photosensitive drum is executed at a timing at which the image of each color is superimposed and transferred to the same position on the recording sheet to be conveyed. FIG.
FIG. 5 is a flowchart illustrating a process for controlling a recording sheet feeding interval when an image is continuously copied using the automatic document feeder 10 or the like. Hereinafter, a process for controlling the sheet feeding interval of the recording sheet when the image is continuously copied will be described with reference to FIGS. 1 to 4 and 6. Here, it is assumed that the CPU 101 performs all controls such as reception of various settings, various displays, control of individual operations of each unit, and monitoring of jams in parallel. Operation, document reading operation, data correction processing operation, operation to determine whether the document is a color image or a black-only image, image forming operation, recording sheet operation, etc. are performed in parallel. , The density data of each reproduced color is stored, and the number of pages of the document, the storage position of the density data of each reproduced color, and the color information are stored in the management table. It is also assumed that the processing for controlling the feeding of the recording sheets sequentially conveys the recording sheets from an appropriate sheet feeding cassette to the position of the recording sheet detection sensor SE2.

(1) To set an initial value, an instruction to disengage the timing clutch 84 and stop the rotation of the timing roller 79 is issued to a timing clutch control unit (not shown) (step S1). The timing clutch control unit receives this instruction, disconnects the timing clutch 84, and stops the rotation of the timing roller 79. (2) Wait until the print mode switching flag becomes "0" (step S2). Incidentally, the print mode switching flag is reset to "0" when the processing operation for controlling the print mode switching is completed.

(3) Referring to the management table stored in the RAM 107, it is determined whether or not there is information on a document to be copied next (step S3). If there is no document information to be copied next, the process waits until new information is stored. (4) If there is information on the original to be copied next,
With reference to the management table stored in M107 and the mode indicated by each selection display lamp 319 of the operation panel 31, it is set for the recording sheet that is currently being copied or is in the standby state (first first sheet). The print mode (hereinafter, referred to as “current print mode”) and the print mode set for the recording sheet to be copied next (hereinafter, referred to as “next print mode”) are compared.

When the current print mode is the color print mode and the next print mode is the monochrome print mode, the print mode switching flag is set to "1" and the paper feed waiting time T is set to t1 (steps S4 to S).
7). If the current print mode is the monochrome print mode and the next print mode is the color print mode, the print mode switching flag is set to "2" and the paper feed waiting time T is set to t2 (step S4, steps S8 to S10). ).

If the current print mode and the next print mode are the same, the paper feed waiting time T is set to t3 (steps S4, S5, S11) or (steps S4, S8, S11). In the next print mode, the selection display lamps 31 on the operation panel 31 are used.
When 9 indicates the color mode, it is the color print mode, and when it indicates the monochrome mode, it is the monochrome print mode. Therefore, in these cases, the current print mode and the next print mode are the same unless the mode indicated by each selection display lamp 319 of the operation panel 31 is changed during continuous copying. Is not set.

The next print mode is the color print mode when the selection indicator lamps 319 indicate the life priority mode and the color information of the next document to be copied in the management table indicates a color image. When the color information indicates an image of only black, the print mode is the single color print mode. Therefore, the print mode is changed to the print mode according to the color information, and the print mode is switched to the print mode according to the color information.

The next print mode is a color print mode regardless of whether the color information indicates a color image or a black-only image, when each selection display lamp 319 indicates the productivity priority mode. Or, if the current print mode is the color print mode (step S5)
Is similarly a color print mode, but if the current print mode is a monochromatic print mode (step S8), the color print mode is set when the color information indicates a color image, and the color print mode is set when the color information indicates a black image only. Becomes a single color print mode. Therefore, the mode is always the color print mode, or the mode is switched from the monochrome print mode to the color print mode, but not from the color print mode to the monochrome print mode.

In this case, the print mode switching flag is stored in the RAM 107, and the paper feed waiting time T is
The set time of the internal timer of U101 is set. (5) The CPU 101 starts counting time using an internal timer (step S12). (6) Wait until the internal timer times out (step S13).

(7) If the internal timer has timed out, wait until the recording sheet detection sensor SE2 detects the conveyed recording sheet (step S14). (8) An instruction to connect the timing clutch 84 to rotate the timing roller 79 is issued to the timing clutch control unit (not shown) (step S15). The timing clutch control unit receives the instruction, connects the timing clutch 84, and sends out the recording sheet from the timing roller 79 toward the transport belt 81.

(9) Wait until the trailing edge of the recording sheet has passed the jam detection sensor SE2 (step S16). Here, the output when the recording sheet detection sensor SE2 detects the recording sheet is turned on, and the output when the recording sheet is not detected is turned off, and an off edge falling from on to off is detected. (10) The trailing edge of the recording sheet is the recording sheet detection sensor SE
2 is detected, after a lapse of a predetermined time from the detection, an instruction to disengage the timing clutch 84 and stop the rotation of the timing roller 79 is issued to the timing clutch control unit (not shown). The process returns to step S3 to determine whether there is information on the original to be read (step S17). Here, the predetermined time is calculated in advance based on an interval between the recording sheet detection sensor SE2 and the timing roller 79 and a conveyance speed of the recording sheet so that a rear end of the recording sheet passes through the timing roller 79 in advance. , And are held in the timing clutch control unit.

As described above, the recording sheet feeding interval is controlled by the feeding waiting times t1 to t3. FIG. 7 is a diagram illustrating a flowchart of a process for controlling switching of the print mode. Hereinafter, processing for controlling the switching of the print mode will be described with reference to FIGS. 1 to 4 and FIG. Here, the processing for controlling the recording sheet feed interval described above is performed in parallel, and the print mode switching flag is set to “1” or “2” during the continuous copying. When the mode is set, or when the mode indicated by each selection display lamp 319 is changed by the operator from the operation panel 31 during standby, for example, when the mode is changed from the color mode to the monochrome mode, the print mode switching flag is set to “1”. When the print mode switching flag is changed to "2" when the monochrome mode is changed to the color mode,
Shall be set.

(1) The print mode switching flag is reset to set an initial value (step S20). (2) Wait until the copying of one image is completed (step S21). For example, the sum of the distance from the position of the recording sheet detection sensor SE2 to the transfer position of the photosensitive drum 611K and the length of the recording sheet in the conveyance direction is divided by the conveyance speed of the recording sheet to determine the time required for the recording sheet to pass. The predetermined time elapses after it is determined in advance that the sheet has passed the recording sheet detection sensor SE2, or the recording sheet detection sensor SE3 disposed downstream of the transfer position of the photosensitive drum 611K. Is detected, the recording sheet passes through the transfer position of the photosensitive drum 611K,
It can be determined that copying has been completed.

(3) When copying of one image is completed,
Or, during standby, the print mode switching flag is “0”
Is determined (step S22). If it is "0", it is not necessary to switch the print mode, and the process returns to the beginning. (4) If not "0", it is determined whether the print mode switching flag is "1" (step S2).
3).

(5) If it is "1", the swing unit 8 in the upper position shown in FIG. 2 to switch the print mode from the color print mode to the single color print mode.
21 is swung downward to change the state to the lower position shown in FIG. 3 (step S24). (6) When the print mode is not “1”, the print mode is “2”. In order to switch the print mode from the monochrome print mode to the color print mode, the swing unit 821 in the lower position shown in FIG. It is moved to change to the state of the upper position shown in FIG. 2 (step S25).

(7) After these switching operations are completed, the print mode switching flag is reset to "0" (step S26). In this case, since the swing unit 821 is swung after the copy of the previous image is completed, the vibration of the swing drive does not adversely affect the copy of the previous image. .

Further, by controlling the sheet feeding interval of the recording sheet according to the sheet feeding waiting time t1 or t2, the vibration of the swinging drive or the like does not adversely affect the copying of the next image. The paper feed waiting times t1 to t3 are determined to values that do not hinder image formation. In particular, at times t1 and t2, the swing unit 8 is used to switch to the corresponding print mode.
It is necessary to determine such a value that the vibration or the like does not adversely affect the image formation even if the oscillating drive 21 is driven. Specifically, if the swing operation of the swing unit 821 is not completed before an image is formed on the next recording sheet, the transfer position becomes unstable and transfer misregistration and color misregistration easily occur. The values of the paper feed waiting times t1 and t2 are determined so as to avoid this.

In this embodiment, when an image is successively copied on the previous recording sheet and the next recording sheet in the same print mode, the heating time required for the next heat fixing and each part are required for each processing. The paper feed waiting time t3 is determined in consideration of the time and the like. When the image is copied in the color print mode and the image is continuously copied in the single color print mode, the swing unit is used in order to prevent transfer and color shifts from occurring. When the swinging operation from the upper side to the lower side of 821 is completed, the leading end of the next recording sheet is closer than the black transfer position by the distance of the peripheral surface from the black image writing position to the black transfer position in the image transfer direction. By determining the paper feed waiting time t2 such that the image quality is kept as low as possible while maintaining the image quality, the image is copied in the single color print mode and the color print is continuously performed. For the case of copying an image not causing transfer shift or color shift over de swing unit 821
When the swinging operation from the lower side to the upper side is completed, the leading end of the next recording sheet is the distance from the leading color transfer position to the circumferential surface from the leading color image writing position to the leading color transfer position in the image transfer direction. By determining the paper feed waiting time t1 so as to be just ahead, a decrease in productivity is suppressed as much as possible while ensuring image quality.

In the present embodiment, the image forming units 61C, 61M, 61Y, and 61K have exactly the same structure in consideration of reduction in manufacturing cost, ease of maintenance, and the like. Although L3 has the same value, the image forming units do not necessarily have to have the same structure, and the distance L2 and the distance L3 do not have to have the same value.

When the swinging operation of the swinging unit 821 from the upper side to the lower side is completed, the CPU 101 sets the photosensitive drums 611C, 611M, and 61 not involved in image formation.
The rotation drive of 1Y is stopped to prevent abrasion of the cleaner member. When the swinging operation of the swinging unit 821 from below to above is completed, the CPU 101 rotates the photosensitive drums 611C, 611M, and 611Y to prepare for color copying.

In the case where the same print mode is continuously executed, the sheet interval X3 may be determined to be different for each print mode. Also, even during the swinging operation of the swing unit 821, the transport belt 81 maintains a constant speed, so that the productivity is not reduced. Detailed Description of Determination of Print Mode FIG. 8 is a diagram illustrating an example of a process of determining a print mode based on the mode and color information indicated by each selection display lamp 319 selected by an operator or the like.

(1) If each selection display lamp 319 indicates the productivity priority mode or the color mode, an image is formed in the color print mode (steps S31, S32,
S35). (2) If each selection display lamp 319 indicates the monochrome mode, an image is formed in the single-color print mode (step S).
33, S36).

(3) When each of the selection display lamps 319 indicates the life priority mode, an image is formed in either print mode in accordance with the color information generated for each document by the document discrimination unit 103 in order to prioritize the life. It is determined whether or not to perform (Steps S34 to S36). FIG. 9 is a diagram illustrating another example of the process of determining the print mode based on the mode and color information indicated by each selection display lamp 319 selected by the operator or the like.

(1) When each selection display lamp 319 indicates the productivity priority mode, it is determined which print mode is the current print mode (steps S41 to S42). (2) If the current print mode is the single-color print mode, the document discrimination unit 103 determines which print mode to form an image according to the color information generated for each document (steps S45 to S47). .

(3) If the current print mode is the color print mode, an image is formed in the color print mode (step S46). (4) If each selection display lamp 319 indicates the color mode, an image is formed in the color print mode (steps S43 and S46). (5) If each selection display lamp 319 indicates the monochrome mode, an image is formed in the single-color print mode (step S).
44, S47).

(6) When each of the selection display lamps 319 indicates the life priority mode, the original discriminating unit 103 determines which print mode to form an image according to the color information generated for each original ( Steps S45 to S47). Here, the number of pages of the document, the storage position of the density data of each reproduction color (the address of the image memory 104), and the document discrimination unit 10
The color information determined by 3 is stored in the management table in the RAM 107 in association with the CPU 101, so that the print mode to be executed for each document can be easily determined by referring to the management table.

Therefore, when each of the selection display lamps 319 indicates the life priority mode, the image can be formed by automatically switching the print mode for each document without the need for the operator to judge the life. Can be prioritized. Further, when each of the selection display lamps 319 indicates the productivity priority mode, the time required for comprehensively forming an image is shortened by the time required for switching the print mode, so that productivity can be prioritized.

In the present embodiment, when each selection display lamp 319 indicates the productivity priority mode, the next print mode is always the color print mode, or
The process is switched from the single-color print mode to the color print mode but not from the color print mode to the single-color print mode. However, the process for indicating the productivity priority mode is not limited to these two, and the life priority mode Any processing may be used as long as the frequency of switching the print mode is made lower than that in the case where the priority is given to the productivity as much as possible. For example, a rule for switching the print mode, such as "switch the print mode when the color information indicates a single color image for three consecutive sheets", is determined in advance, and the print mode is changed according to the previous print mode or color information. May be determined. <Modifications> Although the present invention has been described based on the embodiments, the present invention is, of course, not limited to the above-described embodiments, and the following modifications are conceivable.

(1) In the present embodiment, a part of the transfer unit 82 is moved downward in the single-color print mode, so that the photosensitive drum 611C, which is not involved in image formation,
Although 611M and 611Y are separated from the conveyor belt, any type may be used as long as the photosensitive drum and the conveyor belt are separated from each other.
11C, 611M, and 611Y may be moved upward.

(2) In this embodiment, when each of the selection display lamps 319 indicates the productivity priority mode, the color information of the document to be copied next stored in the management table is recorded for each recording sheet. Although the print mode to be checked and executed is determined, it is not always necessary to determine for each recording sheet when a plurality of copies of the same original are continuously made.
The print mode may be determined only for the first sheet of the same document, and thereafter, the image may be copied in the print mode determined for the first sheet.

In this case, it is not necessary to determine the print mode for the second and subsequent sheets of the same original, and since it is known that the print mode cannot always be switched, it is possible to stop all related control. it can. (3) In this embodiment, a copying machine has been described as an example. However, the present invention is not limited to a copying machine, and may be any image forming apparatus that can form a color image. It may be a printer, a color fax or the like.

(4) In the present embodiment, it is described that the original is a color image or a black-only image. However, the present invention is not limited to only a black-only image, and may be any single-color image. The document may be a color image or a monochrome image. Similarly, "the color information of the document indicates whether the image is a color image or a monochrome image" may be used. The use of the automatic document feeder 10 is determined by the setting of the user or by sensing that a document is set on the document feed tray 11 by a sensor (not shown) or the like. If it is determined that the number 10 is to be used, it is considered that the user is pursuing the productivity, and the productivity priority mode is preferentially executed regardless of the mode indicated by each selection display lamp 319, or The sex priority mode may be automatically selected.

Also, without using the automatic document feeder 10,
If it is determined whether or not the user has placed the document directly at the document reading position by setting the user or sensing the document with a sensor (not shown), etc., In consideration of the fact that the user does not pursue much productivity, the life priority mode is preferentially executed regardless of the mode indicated by each selection display lamp 319, or the life priority mode is automatically selected. May be used.

Further, as in the case of using as a facsimile, it is determined whether or not the information of the image to be formed is obtained from the outside. In consideration of not waiting, the life priority mode may be preferentially executed regardless of the mode indicated by each selection display lamp 319, or the life priority mode may be automatically selected.

[0082]

As described above, according to the present invention,
In the case of the first mode, the two image forming modes are switched according to whether the image to be formed is a color image or a monochrome image. Therefore, the operator does not need to determine whether the image to be formed is a color image or a monochrome image. Further, even when a mixed color image and a single color image are continuously formed, the image forming mode is switched to an image forming mode according to an image to be formed, so that unnecessary wear of the image carrier can be prevented. In the case of (1), since the frequency of switching the image forming mode is lower than that in the first mode, the time for forming an image can be shortened accordingly.

Therefore, the life of the image carrier is given priority or
Either one of the priorities for productivity is selectively possible. According to the present invention, in the first mode, when the image to be formed is a color image, an image is formed in the first image forming mode, and when the image to be formed is a monochromatic image, the second image formation is performed. Since the image is formed in the mode, it is not necessary for the operator to determine whether the image to be formed is a color image or a single color image, and the mixed color image and the single color image are continuously formed. Also, since an image is formed in an image forming mode according to an image to be formed, useless wear of the image carrier can be prevented. In the case of the second mode, an image is formed in the first image forming mode. It is not necessary to switch the image forming mode at all during the formation, and the time for forming the image can be shortened accordingly.

Therefore, the life of the image carrier is given priority or
Either to prioritize productivity can be selectively performed. According to the present invention, in the first mode, when the image to be formed is a color image, an image is formed in the first image forming mode, and when the image to be formed is a monochrome image, the second image is formed.
When the image is formed in the image forming mode, the operator does not need to judge whether the image to be formed is a color image or a single-color image, and the mixed color image and the single-color image are continuously formed. However, since the image is formed in an image forming mode corresponding to the image to be formed, useless wear of the image carrier can be prevented. In the second mode, the first image is formed when the image to be formed is a color image. An image is formed in one of the image forming modes, and in the case of a single-color image, an image formed in one of the image forming modes according to whether a previously formed image is a color image or a single-color image is formed. And the time for forming an image can be shortened accordingly.

Therefore, whether the life of the image carrier is given priority or
Either one of efficiency can be given priority to productivity. According to the present invention, in the first mode, when the image to be formed is a color image, an image is formed in the first image forming mode, and when the image to be formed is a monochromatic image, the second image formation is performed. Since the image is formed in the mode, it is not necessary for the operator to determine whether the image to be formed is a color image or a single color image, and the mixed color image and the single color image are continuously formed. Also, since an image is formed in an image forming mode according to an image to be formed, useless wear of the image carrier can be prevented, and when the image forming apparatus is in the second mode and in the first image forming mode, the first mode is used. When an image is formed in the image forming mode and the image forming apparatus is in the second mode and is in the second image forming mode, the second mode is used when forming a single-color image.
When an image is formed in the same image forming mode and a color image is formed, the image is formed in the first image forming mode. Therefore, the image forming mode is not switched unless absolutely necessary. The time required to form the image can be shortened to the utmost, and the time required to form an image can be reduced, and in some cases, unnecessary wear of the image carrier can be prevented.

Therefore, whether the life of the image carrier is given priority or
Either to give the highest priority to productivity is selectively possible. Further, according to the present invention, when the automatic document reading means is used, the current mode is set to the second mode, so that when the user uses the automatic document reading means which is considered to pursue productivity. Can prioritize productivity.

Further, according to the present invention, when the original reading means is used, the current mode is set to the first mode. Therefore, when the original reading means which is considered to have a relatively long time is used, the image is read. The life of the carrier can be prioritized. Further, according to the present invention, when information of an image to be formed is acquired from the outside, the current mode is set to the first mode. When image information is acquired from the outside, the life of the image carrier can be prioritized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of a digital color copying machine according to an embodiment.

FIG. 2 is a diagram showing a detailed configuration of an image processing system 60.

FIG. 3 is a diagram showing a detailed configuration of the image processing system 60, and shows a state in which a swing unit 821 is stopped at a predetermined lower position.

FIG. 4 is a diagram showing a detailed configuration of a control unit 100.

FIG. 5 is a diagram showing an operation panel 31.

FIG. 6 is a diagram illustrating a flowchart of a process of controlling a recording sheet feeding interval when an image is continuously copied.

FIG. 7 is a diagram illustrating a flowchart of a process for controlling switching of print modes.

FIG. 8 is a diagram illustrating an example of processing for determining a print mode.

FIG. 9 is a diagram illustrating another example of a process for determining a print mode.

[Explanation of symbols]

Reference Signs List 10 automatic document feeder 20 image reader 317 productivity priority mode selection key 318 life priority mode selection key 61C, 61M, 61Y, 61K image forming unit 611C, 611M, 611Y, 611K photoconductor drum 81 transport belt 82 transfer unit 821 swing Moving unit 8291 plate cam 100 control unit 101 CPU 102 image signal processing unit 103 document discrimination unit 104 image memory 106 ROM 107 RAM

Claims (7)

[Claims] 1. An apparatus for forming an image by switching between two image forming modes, an image forming mode using a plurality of image carriers, and an image forming mode using a single image carrier. Input means for inputting whether the mode is the first mode or the second mode; detecting means for detecting whether the image to be formed is a color image or a monochrome image; and, in the case of the first mode, the image to be formed is color. A switching unit that switches between two image forming modes according to whether the image is a monochrome image or a monochrome image, and that sets a switching frequency between the two image forming modes in the second mode to less than that in the first mode. Image forming device. 2. An image forming apparatus comprising: a first image forming mode using a plurality of image carriers; and a second image forming mode using a single image carrier. An input device for inputting whether a mode is a first mode or a second mode, and a detection for detecting whether an image to be formed is a color image or a monochrome image in at least the first mode Means for forming an image in a first image forming state when an image to be formed is a color image, and forming an image in a second image forming state when the image to be formed is a monochrome image An image forming apparatus for forming an image in a first image forming state in the second mode. 3. The detecting means further detects whether an image to be formed is a color image or a monochrome image even in the second mode, and the forming means forms the image in the first mode. When the image to be formed is a color image, an image is formed in the first image forming mode. When the image to be formed is a monochrome image, an image is formed in the second image forming mode. When the image to be formed is in the second mode, the image is formed. When the image is a color image, an image is formed in the first image forming mode, and when the image to be formed is a single-color image, one of the image forming modes depends on whether the previously formed image is a color image or a single-color image. The image forming apparatus according to claim 2, wherein the image is formed by: 4. The image forming apparatus waits in one of a first image forming mode and a second image forming mode, and the detecting unit further includes a second mode and a second mode. Even when the image forming apparatus is on standby, the image forming apparatus detects whether the image to be formed is a color image or a single color image. An image is formed in one image forming mode, and when an image to be formed is a monochromatic image, an image is formed in the second image forming mode, and the image forming apparatus is in the second mode and is in a standby state in the first image forming mode. Forms an image in the first image forming mode and waits in the second mode and in the second image forming mode. When the image to be formed is a monochromatic image, the second image forming Form an image as it is, and when the image to be formed is a color image 3. The image forming apparatus according to claim 2, wherein the image forming apparatus forms an image in a first image forming mode. 5. The image forming apparatus further comprises: an automatic document reading means for reading an original placed at a predetermined position while automatically transporting the original to form an image to be formed; and the automatic document reading means. And a use judging means for judging whether or not the current mode is the second mode when the use judging means judges to use. The image forming apparatus according to any one of claims 1 to 4, 6. The image forming apparatus further includes: a document reading unit that reads a document placed at a document reading position and sets an image to be formed; and a use determining unit that determines whether to use the document reading unit. 5. The apparatus according to claim 1, wherein the input unit inputs the current mode as the first mode when the use determining unit determines to use the current mode. 6. Image forming device. 7. The image forming apparatus further comprising: an acquiring unit that acquires information of an image from outside and sets it as information of an image to be formed; and determines whether the acquiring unit acquires information of the image from outside. The input means inputs the current mode as the first mode when the input source determining means determines that the current mode is the first mode. The image forming apparatus according to any one of claims 1 to 4,