JP2008158075A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for suppressing the occurrence of fog even under a low temperature and low humidity environment by allowing a user not to set an incorrect print mode, and automatically determining a print mode. <P>SOLUTION: The image forming apparatus suppresses fog on smooth paper such as gloss paper by using a medium sensor, detecting the surface of the paper, and changing a circumferential speed difference of an OPC-transfer member in response to the detection results. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile machine that forms an image by an electrophotographic method or an electrostatic recording method.

  A tandem direct transfer multicolor image forming apparatus that forms a multicolor image by transferring toner formed on a plurality of photosensitive drums onto a transfer material conveyed by a conveyor belt as an electrophotographic image forming apparatus. It has been put into practical use.

  In the conventional multicolor image forming apparatus described above, the plurality of photosensitive drums are individually charged by the charging unit, and the electrostatic latent images are individually formed on the plurality of photosensitive drums by the exposure unit. The toner negatively charged by the developing means is formed on the plurality of photosensitive drums and directly transferred to the transfer material P conveyed by the conveyor belt.

  The above-mentioned tandem direct transfer multi-color image device requires only one transfer, so it is inherently superior to character scattering, for example, compared to a method that performs transfer twice using an intermediate transfer member. There is an advantage that a clear image can be obtained.

For example, Patent Document 1 and Patent Document 2 can be cited as conventional examples.
Japanese Patent Laid-Open No. 2001-5310

  By the way, in the above-described tandem direct transfer multicolor image device, in the combination of the negatively charged OPC and the reversal development method that are generally used, the distribution of the toner tribo (the amount of charge per unit mass of the toner) of the toner image is somewhat. In addition to the negative polarity toner having the original charging polarity, positive polarity toner (hereinafter referred to as reversal toner) also exists. However, since the reversal toner is developed in the non-latent image portion on the photosensitive drum, it is transferred to the non-image portion area of the transfer material P and causes a deterioration in image quality (hereinafter, this problem is referred to as “fogging”). ).

  In the conventional technique, in order to prevent the fog reversal toner generated on the photosensitive drum from being transferred to the non-image area of the transfer material P in the transfer process, a peripheral speed difference is provided between the photosensitive drum and the conveyance belt. In addition, the transfer of fog toner is suppressed. However, in the prior art, the peripheral speed difference between the photosensitive drum and the conveyor belt is changed depending on the print mode selected by the user on the printer driver. Therefore, if the user makes an incorrect setting on the printer driver, However, there is a problem that the color shift, which is a negative effect of the peripheral speed difference, is worsened.

  Also, with the conventional technology, since the peripheral speed difference is given even in a low-temperature and low-humidity environment (absolute water content of 5 g / m3 or less), there is a problem that the level of `` fogging '' becomes worse than when the peripheral speed difference is not provided. there were.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of automatically determining a print mode without causing a user to set an incorrect print mode and suppressing occurrence of “fogging” even in a low temperature and low humidity environment. And

  In order to solve the above problems, the present invention has the following means.

  1. A plurality of image forming units having at least an image carrier, charging means for charging the image carrier to a predetermined polarity, and a developing device for visualizing an electrostatic latent image formed on the image carrier with a developer And the transfer material and transfer member for transferring the developer and the smoothness capable of detecting the smoothness of the transfer material by adsorbing the transfer material and passing through each image forming unit. In the image forming apparatus having the property detecting means, from the detection result of the smoothness detecting means, the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer conveying material The movement speed difference Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) is changed.

  2. From the detection result of the smoothness detection means, when the smoothness of the transfer material is high, the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s of the transfer material 2. The image forming apparatus according to 1, wherein the moving speed difference Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) is increased.

  3. A plurality of image forming units having at least an image carrier, charging means for charging the image carrier to a predetermined polarity, and a developing device for visualizing an electrostatic latent image formed on the image carrier with a developer. And the transfer material and transfer member for transferring the toner by adsorbing the transfer material and passing through each image forming unit, and the smoothness capable of detecting the smoothness of the transfer material In the image forming apparatus having the detection means and the temperature / humidity detection means capable of detecting temperature / humidity, the surface of the image carrier according to the detection results of both the smoothness detection means and the temperature / humidity detection means. The moving speed difference Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) between the moving speed v1 [mm / s] and the moving speed v2 [mm / s] of the transfer material is changed. Features.

  4. The detection result of the temperature / humidity detection means shows that the moving speed difference Δv12 [%] (Δv12 = (v1-v2) / v2 * 100) is reduced in a low-temperature and low-humidity environment and moved in an environment other than a low-temperature and low-humidity environment. 4. The image forming apparatus according to 3, wherein the speed difference Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) is increased.

  The smoothness detecting means described in 5.1 to 4 includes a reading means for reading an image of a predetermined area on the surface of the transfer material as an image, and a plurality of photoelectric conversion elements having the predetermined area on the surface of the transfer material in the reading means. An imaging lens that forms an image, a plurality of photoelectric conversion elements that output a voltage according to the amount of received light, an AD conversion circuit that converts the output voltage to digital, and a means for outputting an image in a predetermined area as digital information And a video reading apparatus having a function of calibrating the target image data using the imaged result.

  6. Movement speed difference Δv12 [%] between the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer material (Δv12 = (v1−v2) / v2 The image forming apparatus according to 1 to 5, wherein an absolute value of * 100) is within 5 [%].

  7. The size relationship between the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer carrier is v1 ≦ v2. Image forming apparatus.

  8. It has an automatic discrimination mode capable of detecting the type of transfer material from the detection result of the smoothness detecting means and automatically selecting a print mode according to the result. 7. The image forming apparatus according to 7.

As explained above, according to this explanation,
A plurality of image forming units having at least an image carrier, a charging unit that charges the image carrier to a predetermined polarity, and a developing device that visualizes an electrostatic latent image formed on the image carrier with a developer; A transfer conveying material and a transfer member for transferring toner by adsorbing the transfer material and passing through each image forming unit, and smoothness detection means capable of detecting the smoothness of the transfer material And an image forming apparatus having a temperature / humidity detection means capable of detecting temperature / humidity,
According to the detection results of both the smoothness detecting means and the temperature / humidity detecting means, the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer conveying material By changing the movement speed difference Δv12 [%] (Δv12 = (v1-v2) / v2 * 100), it is possible to prevent incorrect setting of the print mode and improve the “fogging” level even under low temperature and low humidity. it can.

Examples of the present invention will be described below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto.
<Embodiment 1>
FIG. 1 shows an example of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG. 1 is an electrophotographic four-color full-color laser printer having four image forming stations (image forming units), and FIG. 1 is a longitudinal sectional view showing a schematic configuration thereof. The image forming apparatus according to the present invention may be an electrophotographic laser printer, an electrophotographic copying machine, a facsimile, or the like, and an electrostatic recording printer, copying machine, facsimile, or the like. It may be.

  In the image forming apparatus according to the present embodiment, an image is formed on the transfer material P by forming an image using a developer (hereinafter referred to as toner), transferring the toner image onto the transfer material P, and fixing the image. As an endless belt member used in, a transfer material transfer member that is stretched around a plurality of rollers 13, 14, 15, and 16 and circulates in a predetermined direction (in the direction of arrow R11 in FIG. 1) at v2 [mm / s]. A belt 11 is used.

  A laser printer (hereinafter referred to as “image forming apparatus”) shown in FIG. 1 includes four image forming stations (image forming units) in order from the bottom along the conveyance direction of the transfer material P inside the image forming apparatus main body 100. ) Sa, Sb, Sc, Sd. In this order, yellow, cyan, magenta, and black toner images are formed. These image forming stations Sa, Sb, Sc, Sd are provided with process cartridges 7a, 7b, 7c, 7d, respectively. Each process cartridge 7a, 7b, 7c, 7d has a drum as an image carrier. 1a, 1b, 1c, and 1d are disposed in the shape of an electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”). Hereinafter, when it is not necessary to distinguish colors, a, b, c, and d are omitted, and generic names such as “image forming station S”, “process cartridge P”, and “photosensitive drum 1” are used. I write. This also applies to other members.

  The photosensitive drums 1a, 1b, 1c, and 1d are rotationally driven at a predetermined peripheral speed v1 [mm / s] in a counterclockwise direction in FIG. 1 by driving means (not shown). Around the photosensitive drums 1a, 1b, 1c, and 1d, charging devices (primary charging devices) 2a, 2b, 2c, and 2d, exposure devices 3a, 3b, 3c, and 3d, and a developing device are sequentially arranged in the rotation direction. 4a, 4b, 4c, 4d, transfer rollers (transfer members, transfer devices) 12a, 12b, 12c, 12d, cleaning devices 6a, 6b, 6c, 6d and the like are arranged.

  The charging devices 2a, 2b, 2c and 2d uniformly charge the surfaces of the photosensitive drums 1a, 1b, 1c and 1d. The exposure devices (scanner units) 3a, 3b, 3c, and 3d form electrostatic latent images by irradiating the charged photosensitive drums 1a, 1b, 1c, and 1d with laser beams based on image information. . The developing devices 4a, 4b, 4c, and 4d develop toner images by attaching toner to the electrostatic latent images formed by the exposure devices 3a, 3b, 3c, and 3d. The transfer rollers 12a, 12b, 12c, and 12d transfer the toner images formed on the photosensitive drums 1a, 1b, 1c, and 1d to the transfer material P. The cleaning devices 6a, 6b, 6c, and 6d remove toner (residual toner) remaining on the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d after the transfer.

  Here, as shown in FIG. 1, the photosensitive drums 1a, 1b, 1c, 1d, the charging devices 2a, 2b, 2c, 2d, the developing devices 4a, 4b, 4c, 4d, and the cleaning devices 6a, 6b, 6c, 6d. Is integrally formed as a cartridge to form process cartridges 7a, 7b, 7c, and 7d. These process cartridges 7a, 7b, 7c and 7d are further divided into a photosensitive drum unit 50a and a developing unit 45a as shown in a yellow process cartridge 7a. The former photosensitive drum unit 50a is a unit having a photosensitive drum 1a, a charging device 2a, and a cleaning device 6a, while the developing unit 45a is a unit having a developing device 4a (see FIG. 1).

  Hereinafter, the photosensitive drum 1 will be described in detail.

  The photosensitive drum 1 is configured by coating an organic optical semiconductor layer (OPC photosensitive layer) on an outer peripheral surface of an aluminum cylinder having a diameter of 30 mm, for example. Both ends of the photosensitive drum 1 are rotatably supported by a support member (not shown), and a driving force from a drive motor (not shown) is transmitted to one end so that the photosensitive drum 1 in FIG. It is driven to rotate counterclockwise.

  The charging device 2 includes a charging roller (conductive roller) formed in a roller shape, and a charging bias application power source (not shown). The charging device 2 brings the charging roller into contact with the surface of the photosensitive drum 1 and applies a charging bias to the charging roller by the above-described charging bias application power source so that the surface of the photosensitive drum 1 has a uniform polarity and potential. (Uniformly) charged. In the present embodiment, the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d are uniformly charged negatively by the charging devices 2a, 2b, 2c, and 2d.

  The exposure devices 3a, 3b, 3c, 3d are arranged on the left side of the respective photosensitive drums 1a, 1b, 1c, 1d in FIG. 1, and image light corresponding to image signals is scanned by a laser diode (not shown). Irradiated to polygon mirrors 9a, 9b, 9c, 9d rotated at high speed by a motor (not shown). The image light reflected by the polygon mirrors 9a, 9b, 9c and 9d selectively exposes the surfaces of the charged photosensitive drums 1a, 1b, 1c and 1d through the imaging lenses 10a, 10b, 10c and 10d. An electrostatic latent image is formed. In the present embodiment, the electrostatic latent image is formed by removing the charge of the portion irradiated with the image light.

  Each of the developing devices 4a, 4b, 4c, and 4d has a toner container that stores toner of each color of yellow, cyan, magenta, and black. As shown in the yellow toner container 41a, the developing device 4a (see FIG. 1) feeds the toner in the toner container 41a to the toner supply roller 43a by the feed mechanism 42a, and rotates clockwise (in the direction of arrow Z) in FIG. The rotating toner supply roller 43a and the developing blade 44a pressed against the outer peripheral surface of the developing roller 40a are applied to the outer peripheral surface of the developing roller 40a rotating in the arrow Y direction, and charge is applied to the applied toner. Then, a developing bias is applied by a developing bias applying power source (not shown) to the developing roller 40a that is opposed to and in contact with the photosensitive drum 1a on which the electrostatic latent image is formed, thereby forming the electrostatic latent image on the photosensitive drum 1a. A negative toner is attached to the toner image and developed as a toner image. The developing devices 4b, 4c, and 4d for other colors (cyan, magenta, and black) have the same configuration and operation as the yellow developing device 4a.

A transfer device 5 is disposed on the right side of the process cartridges 7a, 7b, 7c, and 7d in FIG. The transfer device 5 has a transport belt (an electrostatic transfer belt as a transfer material transport member) 11 as an endless belt member that circulates (rotates) so as to be in contact with the photosensitive drums 1a, 1b, 1c, and 1d. is doing. The conveyor belt 11 is composed of a film-like member having a volume resistivity of 10 ⁶ to 10 ¹³ Ω · cm and a thickness of 50 to 300 μm. In the present embodiment, the conveyor belt 11 is made of PI (polyimide). The conveyor belt 11 is wound around four rollers 13, 14, 15, and 16 that are arranged in parallel to each other, and is arranged in the vertical direction as a whole. The conveyance belt 11 rotates in a state where the transfer material P is electrostatically adsorbed on the outer peripheral surface at a portion located between the roller 13 and the roller 14 in FIG. As a result, the transfer material P is sequentially transported to the above-described photosensitive drums 1a, 1b, 1c, and 1d at the transfer positions, and the toner images on the photosensitive drums 1a, 1b, 1c, and 1d are transferred as described below. The images are sequentially transferred by the rollers 12a, 12b, 12c, and 12d.

  Inside the transport belt 11, four transfer rollers 12a, 12b, 12c, and 12d are disposed at positions corresponding to the photosensitive drums 1a, 1b, 1c, and 1d, respectively. These transfer rollers 12a, 12b, 12c, and 12d are in contact with the back side of the conveyance belt 11, and the conveyance belt 11 is sandwiched between the photosensitive drums 1a, 1b, 1c, and 1d. As a result, first, second, third, and fourth transfer portions (transfer nip portions) are formed between the photosensitive drums 1a, 1b, 1c, and 1d and the conveyor belt 11. In the present embodiment, a positive transfer bias is applied to the transfer rollers 12a, 12b, 12c, and 12d by a transfer bias application power source (not shown), thereby negative polarity on the photosensitive drums 1a, 1b, 1c, and 1d. The color toner images are sequentially transferred onto the transfer material P in the first to fourth transfer portions.

  Residual toner remaining on the photosensitive drums 1a, 1b, 1c, and 1d without being transferred to the transfer material P when the toner image is transferred is removed by the cleaning devices 6a, 6b, 6c, and 6d. The yellow cleaning device 6a has a cleaning blade 60a that is in contact with the surface of the photosensitive drum 1a and removes residual toner on the surface of the photosensitive drum 1a. Residual toner removed from the surface of the photosensitive drum 1a by the cleaning blade 60a is sequentially sent to a waste toner chamber 53a provided behind the cleaning frame 51a by the toner feeding mechanism 52a.

  As shown in FIG. 1, the image reading sensor 130 that detects the smoothness of the surface of the transfer material P is located downstream of the registration roller pair 19. FIG. 3 shows the configuration of the image reading sensor in this embodiment. As shown in FIG. 3, the image reading sensor 130 has a reflection LED 132 as a light irradiation means, and a CMOS area sensor 131 as a reading means. At this time, the sensor 131 has a lens 133 as an imaging lens, which may be a CCD sensor. . Light using the reflecting LED 132 as a light source is applied to the surface of the transfer material P. The reflected light from the transfer material P is condensed through the lens 33 and imaged on the CMOS area sensor 31. Thereby, the surface image of the transfer material P is read.

  In the present embodiment, the LED 32 is arranged so that the LED light irradiates the surface of the recording medium 101 obliquely at a predetermined angle as shown in FIG.

  In FIG. 1, a detachable feeding cassette 17 is disposed at the bottom of the image forming apparatus main body 100. A plurality of transfer materials P (for example, plain paper, envelopes, transparent films) are stored in the feeding cassette 17 in a stacked state. The transfer material P in the feeding cassette 17 is separated and fed one by one by the driving rotation of the feeding roller 18 (half moon roller) at the time of image formation, and the leading end abuts against the registration roller pair 19, and then the image reading sensor. After being conveyed to the place of 130, it is temporarily stopped, and the image reading sensor 130 reads the surface image of the transfer material P, and simultaneously forms a loop. Thereafter, the rotation of the conveyance belt 11 and the image writing position on the photosensitive drums 1 a, 1 b, 1 c, and 1 d are synchronized, and the sheet is supplied to the conveyance belt 11 by the registration roller pair 19. The transfer material P supplied toward the conveyance belt 11 is brought onto the surface of the conveyance belt 11 by an adsorption roller (leakage toner charging member) 22 as an adsorption member arranged further upstream than the photosensitive drum 1a on the most upstream side. Adsorbed.

  A fixing device 20 is disposed further downstream (upward) of the most downstream image forming station Sd. The fixing device 20 fixes the toner images of a plurality of colors transferred to the transfer material P. The fixing device 20 is in contact with a rotating fixing roller (heating roller) 23 and applies heat and pressure to the transfer material P by being in pressure contact therewith. And a pressure roller 24. That is, the transfer material P transferred so that the toner images of the respective colors on the photosensitive drums 1a, 1b, 1c, and 1d are sequentially overlapped is sandwiched between the fixing roller 23 and the pressure roller 24 when passing through the fixing device 20. While being conveyed, it is heated and pressurized to fix the toner images of a plurality of colors on the surface.

  The image forming operation in the above-described image forming apparatus is as follows. The photosensitive drums 1a, 1b, 1c, and 1d in the process cartridges 7a, 7b, 7c, and 7d are rotated counterclockwise in accordance with the image formation timing, and are uniformly charged by the charging devices 2a, 2b, 2c, and 2d. The The charged photosensitive drums 1a, 1b, 1c, and 1d are exposed according to image signals (image information) by the exposure devices 3a, 3b, 3c, and 3d to form an electrostatic latent image. At this time, a portion that is not exposed becomes a dark portion (high potential portion), and the potential (dark portion potential) is defined as VD. On the other hand, the exposed portion becomes a bright portion (low potential portion), and the potential (bright portion potential) is set to VL. The developing devices 4a, 4b, 4c, and 4d attach toner to the bright portions of the electrostatic latent images described above, and respectively yellow, cyan, magenta, and black toner images on the photosensitive drums 1a, 1b, 1c, and 1d. Form.

  On the other hand, the transfer material P supplied from the feeding cassette 17 to the conveying belt 11 by the feeding roller 18, the registration roller pair 19 and the like is sandwiched between the suction roller 22 and the conveying belt 11, and the surface (outer periphery) of the conveying belt 11 is interposed. And is electrostatically attracted to the surface of the conveyor belt 11 by applying a voltage between the conveyor belt 11 and the suction roller 22. At this time, a positive voltage is applied from the suction roller 22 side, and the roller (suction counter roller) 14 is grounded. The roller 14 is longer than the suction roller 22 in the longitudinal direction. As a result, the transfer material P is stably adsorbed to the transport belt 11 and is transported to the fourth transfer section on the most downstream side.

  The transfer material P adsorbed on the surface of the conveyance belt 11 in this way is sequentially conveyed to the first to fourth transfer portions of the respective colors by the rotation of the conveyance belt 11 in the direction of the arrow R11, and each photosensitive drum 1a, 1b, 1c. , 1d and the transfer rollers 12a, 12b, 12c, 12d, the toner images on the photosensitive drums 1a, 1b, 1c, 1d are sequentially transferred by an electric field (transfer electric field) formed between the transfer rollers 12a, 12b, 12c, 12d.

  The transfer material P onto which the four color toner images have been transferred is separated from the conveying belt 11 by the curvature of the roller (belt driving roller) 13 and is carried into the fixing device 20. The transfer material P is heated and pressed by the heating roller 23 and the pressure roller 24 in the fixing device 20, and the four color toner images are fixed on the surface. The transfer material P after the toner image is fixed is discharged by the discharge roller pair 25 onto the discharge tray 26 formed on the upper surface of the image forming apparatus main body 100 with the image surface facing downward. On the other hand, the residual toner remaining on the surface of the photosensitive drums 1a, 1b, 1c, and 1d after the toner image is fixed is removed by the cleaning devices 6a, 6b, 6c, and 6d, and used for the next image formation. Thus, the four-color full-color image formation is completed.

  Next, means for reducing “fogging” in the transfer process will be described. By providing a speed difference between the moving speed of the photosensitive drum and the moving speed of the conveying belt, the toner is subjected to dynamic stimulation and becomes physically easy to move. As a result, the reversal toner remains on the drum without being transferred to the transfer material P, and only the negative toner in the image portion is transferred to the transfer material P, so that “fogging” can be suppressed and a high-quality print can be obtained. it can.

  In addition, since it is essentially important to give a dynamic stimulus to the reversal toner on the photosensitive drum, it is better to increase the moving speed of the conveyor belt than the moving speed of the photosensitive drum where the reversal toner exists. It has the effect of suppressing fog.

  A conceptual diagram of the above mechanism is shown in FIG.

  From Fig. 2, the fog on the transfer material P is about 4% when the drum, the moving speed, and the moving speed of the conveyor belt are 0%. As a result, the “fogging” on the paper is reduced. In addition, as described above, increasing the moving speed of the conveyor belt relative to the moving speed of the photosensitive drum (in Fig. 2, the sign of% on the horizontal axis is in the negative direction) is effective in reducing `` fogging '' on paper. There is.

  A moving speed difference Δv12 [%] between the moving speed v1 [mm / s] of the photosensitive drums 1a, 1b, 1c, and 1d and the moving speed v2 [mm / s] of the conveyor belt 11 in this embodiment will be described.

The moving speed difference Δv12 [%] is defined by the following equation.
Δv12 [%] = (v1-v2) / v2 * 100
In the present embodiment, the moving speed difference Δv12 is changed by changing the moving speed v1 of the photosensitive drums 1a, 1b, 1c, and 1d.

  The moving speed v1 of the photosensitive drums 1a, 1b, 1c, and 1d is controlled by the CPU 74 controlling the rotational drive of a DC motor (not shown) that is a driving source of the photosensitive drums 1a, 1b, 1c, and 1d.

  If the moving speed difference between the photosensitive drum and the conveyor belt is too large, excessive transfer force is generated when the transfer material P conveyed by the conveyor belt comes into contact with the photosensitive drum, and the position deviates from the original transfer printing position. Since there is a high possibility of printing, the amount of deviation of the printing position for each color station becomes large (hereinafter, this phenomenon is referred to as “color deviation”). Therefore, it is necessary to set a moving speed difference that can reduce “fogging” within a range in which “color misregistration” does not deteriorate.

  In general, the levels of “fogging” and “color shift” vary depending on the type of transfer material P. When the surface of the transfer material P is smooth, the level of “fogging” is poor, and the influence on “color shift” with respect to the absolute value of the moving speed difference Δv12 is small. Conversely, when the surface is not smooth, the level of “fogging” is good, and the influence on “color shift” with respect to the absolute value of the moving speed difference Δv12 is large. Therefore, the change in the moving speed v1 of the photosensitive drums 1a, 1b, 1c, and 1d should be determined by the smooth state of the paper.

  Table 1 shows the results of confirmation of the dependence of the “fogging” and “color shift” levels on the moving speed difference Δv12 for the two types of transfer materials P in this example.

尚、表1における「カブリ」、「色ずれ」レベルの判定基準は以下の通りである。
1：発生が認められないレベル
3：実用上問題にならない程度のレベル
5：目立つレベル
本検討結果によると、表面が平滑でない普通紙の場合、移動速度差Δv12をつけると、「カブリ」レベルは良化するものの、「色ずれ」レベルは悪化する。普通紙の場合、移動速度差Δv12が0%の時でも、「カブリ」レベルは実用上問題にならない程度のレベルであるため、「色ずれ」レベルを悪化させないためにも、移動速度差Δv12をつけないほうが良い。

The determination criteria for the “fogging” and “color shift” levels in Table 1 are as follows.
1: Level where occurrence is not recognized
3: A level that does not cause any practical problems
5: Conspicuous level According to the results of this study, when the paper has a non-smooth surface and the moving speed difference Δv12 is applied, the “fogging” level is improved, but the “color shift” level is deteriorated. In the case of plain paper, even when the movement speed difference Δv12 is 0%, the “fogging” level is a level that does not cause a problem in practice. Therefore, in order not to deteriorate the “color shift” level, the movement speed difference Δv12 is It is better not to put it on.

  On the other hand, in the case of smooth paper, the moving speed difference Δv12 that achieves both “fogging” and “color misregistration” is −1 to −3%, so it is desirable to add the moving speed difference Δv12.

  In the conventional technology, the user determines whether the transfer material P is plain paper or smooth paper, and the type of the transfer material P is set on the printer driver. With this method, if the user mistakenly sets the type of the transfer material P, for example, if plain paper is mistakenly set as smooth paper, printing is performed with the moving speed difference Δv12 attached, and the plain paper “ The level of “color shift” gets worse. On the other hand, if smooth paper is mistakenly set as plain paper, the moving speed difference Δv12 is printed at 0%, which causes a problem that the “fogging” level deteriorates.

  In the present invention, the image reading sensor 130 automatically determines the smoothness of the surface of the transfer material P, the plain paper is printed in the plain paper mode, and the smooth paper has the auto mode in which it is printed in the smooth paper mode. Therefore, the type of the transfer material P is not erroneously set, and as a result, a print satisfying both “fogging” and “color misregistration” can be obtained for both plain paper and smooth paper.

In the above-described embodiment, the moving speed difference Δv12 is changed by changing the moving speed v1 of the photosensitive drums 1a, 1b, 1c, and 1d. The same effect as the example can be obtained.
<Embodiment 2>
Next, an image forming apparatus according to a second embodiment of the present invention will be described. The same components as those of the image forming apparatus of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The present embodiment is characterized in that the moving speed difference Δv12 is not applied under the low temperature and low humidity environment, and the moving speed difference Δv12 is applied under the other environment, based on the detection result of the atmosphere environment detecting means.

  Humidity in the air if the absolute moisture content inside or outside the image forming device is 5g / m3 or higher in a high temperature and high humidity environment (eg 30 ° C / 80% RH) or normal environment (eg 23 ° C / 60% RH) Therefore, when the number of prints increases, the toner tribo attenuates, the toner deteriorates, and the reversal toner increases. As a result, the reverse toner is dominant in “fogging”. As to the means for suppressing the fog that is dominant by the reversal toner, as described in the prior art and Embodiment 1, the moving speed v1 [mm / s] of the photosensitive drums 1a, 1b, 1c, and 1d and the conveying belt 11 The moving speed difference Δv12 [%] from the moving speed v2 [mm / s] is attached.

  However, in a low-temperature and low-humidity environment (for example, 15 ° C / 10% RH) with an absolute moisture content of 5 g / m3 or less, because the humidity in the air is low, among the toners that have deteriorated due to an increase in the number of puddings, there are few reversal toners. Instead, the number of nonpolar toners having no polarity is relatively large. As a result, “fogging” that occurs in a low-temperature and low-humidity environment is not dominated by reversal toner, but becomes “non-polar fog” in which non-polar toner dominates, resulting in high-temperature and high-humidity environments (for example, 30 ° C / 80% RH) and normal This property is different from “reversal fog” in which reversal toner generated in an environment (for example, 23 ° C./60% RH) is dominant.

  As described in the first embodiment, the moving speed difference Δv12 [%] between the moving speed v1 [mm / s] of the photosensitive drums 1a, 1b, 1c, and 1d and the moving speed v2 [mm / s] of the conveyor belt 11 is obtained. When the toner is turned on, the toner is subjected to dynamic stimulation, and becomes easy to move faithfully by the transfer electric field. As a result, the reversal toner remains on the drum without being transferred to the transfer material P, so that “reversal fog” can be suppressed as shown in FIG.

  However, since the nonpolar toner has no polarity, it does not react to the transfer electric field even if the moving speed difference Δv12 is applied, and it becomes easier to transfer the transfer material P by the dynamic scraping force by adding the moving speed difference Δv12. “Non-polar fog” gets worse.

  FIG. 4 shows the results of examining the dependence on the moving speed difference Δv12 of “non-polar” fog under low temperature and low humidity with an absolute water content of less than 5 g / m 3 in this example.

  Unlike the result of “inverted fog” in FIG. 2, “non-polar fog” is deteriorated by adding the moving speed difference Δv12, and the best fog is obtained when the moving speed difference Δv12 is 0%.

  Therefore, in a low-temperature and low-humidity environment where the absolute moisture content is less than 5 g / m3 where “non-polar fog” occurs, the movement speed difference Δv12 is not applied, and in an environment where the “inverted fog” occurs where the absolute moisture content is 5 g / m3 or more. It is desirable to set a speed difference Δv12.

  Also in this example, similarly to the first embodiment, the moving speed difference Δv12 is given only to smooth paper from the detection result of the image reading sensor 130. In addition, in this embodiment, the moving speed difference Δv12 is set as shown in Table 2 from the results of the temperature and humidity sensor.

以上のように上述した本実施形態においては、映像読取センサに加えて、画像形成装置内外の雰囲気温湿度の検知手段を有し、その検知結果に応じて、低温低湿下では移動速度差Δv12をつけず、それ以外の環境下では移動速度差Δv12をつけることで「カブリ」レベルを良好なレベルで抑制することができる。

As described above, in the above-described embodiment, in addition to the image reading sensor, the image forming apparatus has an ambient temperature / humidity detection unit inside and outside, and according to the detection result, the movement speed difference Δv12 is set under low temperature and low humidity. In other environments, the “fogging” level can be suppressed at a favorable level by adding the moving speed difference Δv12.

  In the above-described embodiment, the movement speed difference Δv12 is changed by changing the movement speed v1 of the photosensitive drums 1a, 1b, 1c, and 1d. The same effect as the embodiment can be obtained.

  Embodiments 1 and 2 have been described above.

1 is a diagram illustrating an example of an image forming apparatus according to the present invention. It is a figure which shows a fog reduction mechanism. It is a figure which shows the structure of the image | video reading sensor in this embodiment. It is a figure which shows the speed difference dependence of the fog in low temperature and low humidity.

Explanation of symbols

1a, 1b, 1c, 1d Photosensitive drum 2a, 2b, 2c, 2d Charging device 3a, 3b, 3c, 3d Exposure device 4a, 4b, 4c, 4d Developing device 6a, 6b, 6c, 6d Cleaning device 7a, 7b, 7c , 7d Process cartridge 11 Conveyor belt (endless belt member)
12a, 12b, 12c, 12d Transfer roller 13, 14, 15, 16 Roller 22 Adsorption roller (toner charging member)
100 Image forming apparatus main body

Claims (8)

A plurality of image forming units having at least an image carrier, a charging unit that charges the image carrier to a predetermined polarity, and a developing device that visualizes an electrostatic latent image formed on the image carrier with a developer; Smoothness detection capable of detecting the transfer material and transfer member for transferring the developer and the smoothness of the transfer material by adsorbing the transfer material and passing through each image forming unit An image forming apparatus comprising:
From the detection result of the smoothness detecting means, the moving speed difference Δv12 [%] (Δv12 = (Δv12 =)) between the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer carrier. An image forming apparatus characterized by changing (v1-v2) / v2 * 100). From the detection result of the smoothness detecting means, the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer carrier when the smoothness of the transfer material is high 2. The image forming apparatus according to claim 1, wherein the moving speed difference Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) is increased. A plurality of image forming units having at least an image carrier, a charging unit that charges the image carrier to a predetermined polarity, and a developing device that visualizes an electrostatic latent image formed on the image carrier with a developer; A transfer conveying material and a transfer member for transferring toner by adsorbing the transfer material and passing through each image forming unit, and smoothness detection means capable of detecting the smoothness of the transfer material And an image forming apparatus having a temperature / humidity detection means capable of detecting temperature / humidity,
According to the detection results of both the smoothness detecting means and the temperature / humidity detecting means, the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer conveying material The moving speed difference Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) is changed. As a result of detection by the temperature and humidity detection means, the moving speed difference Δv12 [%] (Δv12 = (v1-v2) / v2 * 100) is reduced in a low temperature and low humidity environment, and the moving speed difference is different in an environment other than a low temperature and low humidity environment. 4. The image forming apparatus according to claim 3, wherein Δv12 [%] (Δv12 = (v1−v2) / v2 * 100) is increased.   The smoothness detecting means according to claim 1 includes a reading means for reading a predetermined area on the surface of the transfer material as an image, and a predetermined area on the surface of the transfer material in the reading means. An imaging lens that forms an image on the conversion element, a plurality of photoelectric conversion elements that output a voltage according to the amount of received light, an AD conversion circuit that converts the output voltage to digital, and an image in a predetermined area is output as digital information An image forming apparatus comprising: an image reading apparatus having a function of photographing the surface of the transfer material and calibrating target image data using the photographing result.   Difference in moving speed Δv12 [%] between the moving speed v1 [mm / s] of the image carrier surface and the moving speed v2 [mm / s] of the transfer conveying material (Δv12 = (v1−v2) / v2 * 100 6. The image forming apparatus according to claim 1, wherein an absolute value of) is within 5%.   7. The magnitude relationship between the moving speed v1 [mm / s] of the surface of the image carrier and the moving speed v2 [mm / s] of the transfer material is v1 ≦ v2. Image forming apparatus.   The automatic discrimination mode capable of detecting a type of a material to be transferred from a detection result of the smoothness detecting means and automatically selecting a print mode according to the result is provided. 7. The image forming apparatus according to 7.

Images