JP4621009B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a black and white color image forming apparatus such as an electrophotographic copying machine or a printer.

  In recent years, image forming apparatuses such as electrophotographic apparatuses are required to have high speed, high functionality, and high reliability in both monochrome and color, and various types of printers have been put on the market.

  In color machines, demand is growing year by year, such as customers who purchase new color machines and replacements from monochrome.

  The color machine has a configuration in which a plurality of different color image forming units are arranged in series and a transfer sheet is conveyed by a belt-shaped conveyance unit, and a toner image is sequentially transferred in a multiple manner (hereinafter referred to as an inline method). Recently, color printers have become mainstream because color images can be formed at high speed.

  In the color mode, the color machine transfers and fixes toner images of a plurality of colors Y, M, C, and Bk on a recording sheet to form a color image. On the other hand, in the monochrome mode, only the Bk toner image is transferred and fixed on the recording paper to form a monochrome image. In this type of image forming apparatus, when the process speeds of the monochrome mode and the color mode are the same, the productivity of the monochrome mode and the color mode is the same. In order to promote replacement of a monochrome machine with a color machine, it is necessary to significantly improve the productivity of the monochrome mode as compared with the color mode, and it is necessary to increase the process speed in the monochrome mode. Such an apparatus has already been proposed (see, for example, Patent Document 1). And it has already been put on the market as a black and white combined color image forming apparatus, and this encourages customers to increase their purchasing motivation such as replacement of a monochrome image forming apparatus with a color image forming apparatus.

Further, it is also known that a color machine, unlike a monochrome machine, performs color image correction control such as density control in a multi-rotation operation before power-on (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-177283 Japanese Patent Laid-Open No. 10-039716

  As described above, in the monochrome combined color machine, there is a problem in that it takes a long time for the monochrome machine to be able to print after being turned on. Further, as other color image correction control, there is also control such as registration correction for optimizing the printing position when overlapping each color image. Because of this control, even in devices where the image formation speed in monochrome mode is faster than in color mode, such as a black-and-white color machine, multiple rotation operations before power-on, after door opening / closing The previous multi-rotation operation is performed at a color image forming speed in order to perform color image correction control, and there is a problem that the waiting time is long.

  The present invention has been made paying attention to the above-mentioned problems, and its purpose is to become familiar with monochrome machines by shortening the control sequence time after power-on or from door open / close until printing is possible. However, it is intended to solve the problem that the waiting time of the color machine is long for the customer group and to provide an image forming apparatus with high productivity. Another object of the present invention is to provide a color image forming apparatus that further promotes the replacement of a monochrome machine with a color.

This invention solves the said subject by providing the following structures.
(1) A plurality of image forming units each having an image carrier for carrying a toner image, and a toner image carried on each image carrier of the plurality of image forming units, a transfer material, or a plurality of image formations Density correction based on a detection result obtained by detecting a toner image formed on the transfer unit by the transfer unit and transferred to the transfer unit that transfers the transfer material to the transfer unit. And a control unit for performing the cleaning of the toner image, an image forming speed in a full color mode for forming a color image, or an image forming speed in a monochrome mode for forming a black and white image having a higher image forming speed than in the full color mode. An image forming apparatus comprising: a cleaning unit configured to detect the temperature and humidity of the image forming apparatus; The second stage is calculated based on the detection result detected by the detection means before the power is turned off, and is calculated based on the first moisture amount stored in the storage means and the detection result detected by the detection means when the power is turned on. When the difference between the first moisture amount and the second moisture amount is equal to or greater than a predetermined value, the conveying unit is cleaned at the image forming speed in the monochrome mode. Thereafter, the density correction is performed at the image forming speed in the full color mode, and after the density correction is completed, the transport unit is cleaned again at the image forming speed in the monochrome mode, and the first moisture amount and the When the difference from the second moisture amount is less than a predetermined value, the image forming apparatus performs only cleaning of the conveying unit at the image forming speed in the monochrome mode and does not perform the density correction.

  As described above, according to the present invention, the time from when the power is turned on until printing is possible, and the time until printing is possible when the door is opened / closed is greatly reduced by the control sequence. Depending on the respective use conditions at the image forming speed, high productivity can be obtained and user satisfaction can be improved.

  Examples of the present invention will be described below.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

  The image forming apparatus according to the present exemplary embodiment has a configuration in which process stations 8M, 8C, 8Y, and 8K as first, second, third, and fourth image forming units are stacked in a substantially vertical direction (substantially in a gravitational direction). It has. Each of the process stations 8M to 8K forms magenta, cyan, yellow, and black images.

  Each of the process stations 8M to 8K includes a process cartridge and an exposure device. Each process cartridge includes φ30 photosensitive drums 9M, 9C, 9Y, and 9K as image carriers, and chargers 10M, 10C, 10Y, and 10K as charging means, and developers (toners) of the above-described colors that develop a latent image. A developing device 12M, which is a developing means including developing sleeves 12M1, 12C1, 12Y1, and 12K1, which are developer carriers that are supported on the surface of the photosensitive drums 9M to 9K. 12C, 12Y, and 12K, and cleaners 14M, 14C, 14Y, and 14K, respectively. The exposure unit includes 11M, 11C, 11Y, and 11K for each process station.

  The developing units 12M, 12C, 12Y, and 12K of the present embodiment are of a non-contact developing type, and the developing sleeves 12M1, 12C1, 12Y1, and 12K1 that are developer carrying members of the developing units 12M to 12K are the photosensitive drums 10M to 10M. A developing bias in which a rectangular AC voltage and a DC voltage are superimposed is applied between the photosensitive drums 10M to 10K and the developing sleeves 12M1 to 12K1 at the time of development. . The apparatus used in the present embodiment has an environmental sensor (not shown), and the sensor detects temperature and relative humidity and implements control for selecting an appropriate bias according to the environment.

  Further, along each of the process stations 8M to 8K, a transfer conveyance belt 7 having an inner peripheral length of 650 mm constituting a transfer material carrying / conveying means for carrying and transferring the transfer material 1 is disposed. The transfer conveyance belt 7 is stretched around a φ20 driving roller 5, a φ20 driven roller 6, and a φ20 belt stretching roller 20 as belt driving means, and rotates in the direction of arrow A.

  The apparatus used in this embodiment has two types of modes, a full color mode and a monochrome mode. In the full color mode, printing is performed at an image forming speed of a process speed of 85 mm / sec. In the monochrome mode, an image of 170 mm / sec is printed. Printed at the forming speed. At this image forming speed, a color print is output at 13 PPM, a monochrome print is output at 26 PPM, and monochrome enables higher productivity than color.

  The exposure unit is an optical system composed of a two-beam semiconductor laser, a plurality of lenses, and a four-sided rotary polygon mirror, and the exposure units 11M, 11C, and 11Y do not have speed switching means. On the other hand, the exposure unit 11k has a rotating polygon mirror speed of 2 and can be switched to a high speed rotation of 16000 rotations in the full color mode and 32000 rotations in the monochrome mode. The semiconductor lasers of the exposure units 11M, 11C, 11Y, and 11K have two beams as described above.

  First, the operation in the full color mode will be described with reference to FIG.

  As described above, the image forming speed is a low speed of 85 mm / sec. When the photosensitive drum 9M is uniformly charged by the charger 10M in the first process station 8M, a laser beam corresponding to magenta image information is irradiated to form an electrostatic latent image. The magenta toner of the developing device 12M is transferred to the electrostatic latent image by the developing bias, and a magenta toner image is formed on the photosensitive drum 9M.

  On the other hand, the recording paper 1 serving as a transfer material in the paper feeding unit 2 is taken out one by one by the pickup roller 16 and fed to the transfer conveyance belt 7 through the paper passing path 4, and the suction roller 18 serving as the suction means. By the action, it is adsorbed and supported on the transfer conveyance belt 7. The recording paper 1 is conveyed to the transfer portion T1 in time with the magenta toner image on the photosensitive drum 9M, and the magenta toner image is transferred onto the recording paper 1 by the action of the transfer device 13M.

  In the second to third process stations 8C, 8Y, and 8K, the cyan toner image, the yellow toner image, and the black toner image are placed on the photosensitive drums 9C, 9Y, and 9K in the same manner as the first process station 8M. As the recording paper 1 is formed and conveyed by the transfer conveyance belt 7 to the transfer portions T2, T3, T4 of the second to fourth process stations 8C, 8Y, 8K, the transfer units 13C, 13Y, 13K Due to the action, the toner images of the respective colors are overlaid and transferred.

  The recording paper 1 onto which the toner images for four colors have been transferred at the fourth process station 8K at the most downstream side is conveyed to the fixing unit 15, where the toner image is fixed and discharged to the discharge unit 3. .

  Residual toner is removed from each of the photosensitive drums 9M to 9K after transfer by cleaners 14M to 14K, respectively, and used for the next image formation.

  Next, the case where the image output, that is, the monochrome mode is performed only by the fourth process station 8K at the most downstream will be described with reference to FIG.

  In the monochrome mode, the image forming speed is performed at a high speed of 170 mm / sec as described above. When image output is performed only at the fourth process station 8K on the most downstream side, the driving of the developing units 12M, 12C, and 12Y of the first to third process stations 8M, 8C, and 8Y on the upstream side is stopped. Specifically, the rotational driving of the developing sleeves 12M1 to 12K1 is stopped. At this time, the photosensitive drums 9M to 9Y of the first to third process stations 8M, 8C, and 8Y that do not perform image formation come into contact with the transfer conveyance belt 7 and are driven at the same high image forming speed as in the monochrome mode. Thus, the recording paper 1 functions as a transport roller for transporting the recording paper 1 to the fourth process station 8K that performs image output.

  FIG. 5 is a control block diagram of the present embodiment. Such a control mode has the same configuration in each of the process stations 8M, 8C, 8Y, and 8K, and therefore the first process station 8M will be described as an example. Although not shown in FIG. 4, one control unit 37 is provided in the image forming apparatus. The photosensitive drum 9M and the developing unit 12M are driven by a drive motor 34 that is a variable speed as a driving unit. The photosensitive drum 9M is driven by a driving motor 34 via a driving gear 35, and the developing device 12M is driven by a driving motor 34 via a clutch 36 capable of releasing driving transmission. And the drive control of the drive motor 34 and the clutch 36 is performed by the control part 37 which is a control means. The drive motor 34 can switch the speed in the monochrome mode and the full color mode. Even if one drive motor 34 is provided for each of the process stations 8M to 8K or one for each of the plurality of process stations, all the process stations 8M are provided. One may be provided for ˜8K. In the present embodiment, the drive motor 34 and the drive gear 35 constitute an image carrier drive unit 38 of the image carrier drive means, and the drive motor 34 and the clutch 36 constitute a development drive unit 39 corresponding to the development drive means.

  Next, a control sequence (hereinafter referred to as an initial sequence) from when the power is turned on until printing is possible (hereinafter referred to as ready) will be described.

  Each task executed in the initial sequence is described in Table 1 below.

  Table 1 shows the working time of each task, excluding the belt cleaning work.

  First, in task 1, the presence or absence of CRG is detected. Each process cartridge is provided with a tag (non-contact communication device) (not shown), and the presence or absence of the cartridge can be detected.

  In task 2, residual paper is detected by JAM or the like in the apparatus. This is detected by a sensor (not shown) provided in the paper conveyance path.

  Task 3 is detection of an environmental change by an environmental sensor. The environmental information before power-on is stored in a memory (not shown) in the apparatus, and compared with the information, it is determined whether environmental fluctuations exceed a threshold value. The environmental sensor includes a temperature sensor and a relative humidity sensor, and calculates an absolute water content from the information. The absolute water content is the weight of water present in 1 m 3, for example, 1.06 g at 15 ° C. and 10% RH, and 21.74 g at 30 ° C. and 80% RH. The total water content is stored every 30 minutes in a memory (not shown) of this apparatus, and only when there is a difference of 3 g or more from the absolute water content value stored before the power is turned off. The density control of task 6 described later is executed.

  In task 4, when the density control is executed, the image forming speed is the speed in the color mode, which is a low speed of 85 mm / sec. If it is determined that density control execution is unnecessary, the image forming speed in the monochrome mode is operated at a high speed of 170 mm / sec. The motor speed is switched to achieve these speeds.

  In Task 5, since there is a possibility that the toner surface remains on the belt surface due to JAM or the like at the determined speed, cleaning for two belt rounds is performed.

  In task 6, density control is executed. In the density control, the reflectance of the belt itself is detected by an optical sensor (not shown) arranged in the vicinity of the driving roller 5 in FIG. 4 on the first round of the belt, and the patch pattern as shown in FIG. Are printed on the belt for four colors M, C, Y, and K, the deviation from the appropriate density is calculated from the amount of reflected light, and density correction is performed.

  In task 7, the patch pattern printed on the belt is cleaned.

  Task 8 performs temperature control to make the fixing temperature ready for printing.

  The control flow of the above task is shown with the flowchart of FIG.

  In this flowchart, assuming that task 1 to task 3 are STEP1, the time required for STEP1 is 1.2 sec. The time required for the speed switching is 0.6 sec. The time required for density control and belt cleaning is 15.3 sec.

  In this embodiment, when it is determined that execution of density control is not necessary, speed switching is performed, and switching to the speed in the monochrome mode, which is faster than the image forming speed in the normal color mode, is performed for belt cleaning. The required time is 7.7 sec compared to 14.9 sec, and the time from power-on to ready without executing density control is 9.4 sec, whereas the time required when the speed is not switched is 16.5 sec. The time can be reduced by about 43%. As a result, even when the density control execution is not necessary, it has become possible for the user who has been waiting for a certain time to greatly reduce the time.

  These can also be applied to apparatuses using other image correction controls. It can also be applied to control in door opening / closing. Needless to say, the present invention can also be applied to an intermediate transfer system other than the apparatus used in this embodiment.

(Second embodiment)
A further improved example will be described.

  Since the apparatus is the same as that of the first embodiment, description thereof is omitted.

  An initial sequence from when the power is turned on until printing is ready will be described.

  Since each task is the same as in the second embodiment, a description thereof will be omitted.

  In this embodiment, even when the density control is executed, the belt cleaning before and after the density control is performed at the speed in the monochrome mode so as to shorten the time.

  Next, actual control is shown in the flowchart of FIG.

  The difference from the first embodiment is that a speed switching task is input before and after execution of density control.

  As a result of inputting these controls into the apparatus and measuring the time, even when density control is performed, the belt cleaning is performed by switching to a higher speed and a speed in the monochrome mode. The time was 6 seconds, and 31% of the time was shortened compared to 48.9 seconds when the speed was not changed during belt cleaning. As a result, even when the density control is executed or not executed, it is possible to significantly reduce the time for the user who has been waiting for a certain time.

  These can also be applied to apparatuses using other image correction controls. It can also be applied to control in door opening / closing. Needless to say, the present invention can also be applied to an intermediate transfer system other than the apparatus used in this embodiment.

Flow chart showing the control of the first embodiment Flowchart showing the control of the second embodiment Diagram showing patch pattern The figure which shows the apparatus used for the 1st and 2nd Example Control block diagram used in the first and second embodiments

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording paper 2 Paper feed part 3 Discharge part 4 Paper path 5 Drive roller 6 Driven roller 7 Transfer conveyance belt (transfer material conveyance means)
8M, 8C, 8Y, 8K process station (image forming means)
9M, 9C, 9Y, 9K Photosensitive drum (image carrier)
12M, 12C, 12Y, 12K Developer (Developer)
13M, 13C, 13Y, 13K Transfer device (transfer means)
18 Adsorption roller 20 Belt stretch roller

Claims (1)

A plurality of image forming means each having an image carrier for carrying a toner image;
A transfer unit that transfers a toner image carried on each image carrier of the plurality of image forming units to a transfer material or a conveying unit that conveys the transfer material to the plurality of image forming units ;
A control unit that performs density correction based on a detection result of detecting a toner image formed by the image forming unit and transferred onto the conveying unit by the transfer unit;
Cleaning means for cleaning the toner image at an image forming speed in a full color mode for forming a color image, or an image forming speed in a monochrome mode for forming a black and white image at a higher image forming speed than in the full color mode;
An image forming apparatus comprising,
A detecting means for detecting the temperature and humidity of the image forming apparatus;
The control means calculates based on the detection result detected by the detection means before turning off the power, and calculates based on the first moisture amount stored in the storage means and the detection result detected by the detection means when the power is turned on. 2 is compared with the amount of water,
When the difference between the first moisture amount and the second moisture amount is equal to or larger than a predetermined value, the image in the full color mode is cleaned after cleaning the conveying unit at the image forming speed in the monochrome mode. The density correction is performed at the forming speed, and after the density correction is completed, the conveying unit is cleaned again at the image forming speed in the monochrome mode,
When the difference between the first moisture amount and the second moisture amount is less than a predetermined value, only the transport unit is cleaned at the image forming speed in the monochrome mode, and the density correction is not performed. An image forming apparatus.

Images