JP2011059190A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that in an image forming apparatus in which an intermediate transfer body, a transfer conveying body or a photoreceptor belt is used as an image carrier, a belt is damaged or backing members (an opposing means and an opposing member) are stuck to the belt and further, to enable high reliable, easy and accurate density control, position control, etc. <P>SOLUTION: The image forming apparatus includes a contact/separation mechanism 50 for a sensor opposing member as an opposing means contact/separation means freely bringing a sensor opposing member 49 and the back surface of an intermediate transfer belt 10 into contact with each other or separating them from each other. The contact/separation mechanism 50 for the sensor opposing member includes a sensor opposing shaft 48, a drive motor 51 as a drive source connected to one end of the sensor opposing shaft 48 and a home position sensor not illustrated, detecting the home position of the sensor opposing member 49. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, a plotter, or a multifunction machine having a plurality of functions, and more particularly, an intermediate transfer member, a transfer carrier, or a photosensitive belt as an image carrier. The present invention relates to an image forming apparatus to be used.

When forming an image with a copying machine using an electrophotographic system, a toner image of each color of a cyan (C) image, a magenta (M) image, a yellow (Y) image, and preferably a black (K) image is used. A full color image is formed by forming the image on the image carrier and transferring the toner image of each color on the sheet material at the transfer position of each image carrier. In an image forming process using an electrophotographic system, the characteristics of the photoconductor and the developer change with time and also in the usage environment. Further, the positional deviation of the toner image also occurs.
In other words, the image density tends to fluctuate due to fluctuations in the characteristics of the photosensitive member and developing device due to the number of image formations, manufacturing variations, and usage environment. Therefore, density control and position control are performed prior to normal image formation. In particular, since the above-described color image forming apparatus is required to maintain a delicate color balance, more accurate density and position control is required for each of M, C, Y, and K.

  In order to prevent such changes in toner image density and misalignment, an optical sensor is disposed opposite to the belt surface as an image carrier (intermediate transfer member) in a broad sense. In order to examine the change in the toner image, a reference toner image correction pattern is usually drawn in advance, the toner image correction pattern is detected by a plurality of optical sensors, and the toner image is corrected based on the result.

  However, the actual intermediate transfer belt has irregularities in the main scanning direction and the sub-scanning direction (sheet material movement direction), and there is a problem that the toner image correction pattern cannot be detected accurately. In order to solve this problem, for example, a technology that enables accurate toner image detection using a backing member having a simple structure that can correct belt deformation has been proposed (see, for example, Patent Document 1).

However, in the technique described in Patent Document 1, since the backing member always contacts and slides on the rotating belt, the belt may be damaged or the backing member may stick to the belt. There is a problem that density control and position control of a toner image cannot be performed.
The above-described problem similarly exists in an image forming apparatus that uses a transfer carrier or a photosensitive belt as an image carrier in a broad sense, in addition to an image forming apparatus that uses an intermediate transfer member.

  Therefore, the present invention has been made in view of the above-described circumstances, and particularly in an image forming apparatus in which an intermediate transfer member, a transfer carrier, or a photosensitive belt is used as an image carrier, the belt is scratched, To improve and solve the problem that the backing member (opposing means / opposing member) sticks to the belt, and thus to realize and provide an image forming apparatus capable of highly reliable, easy and accurate density control and position control. Main purpose.

In order to solve the above-described problems and achieve the above-mentioned object, the invention according to each claim employs the following characteristic means / invention-specific matters (hereinafter referred to as “configuration”).
According to the first aspect of the present invention, an endless belt-shaped image carrier that carries a toner image, a transfer unit that transfers the toner image on the image carrier to a sheet-like recording medium, and the image carrier. At least one toner image detecting means arranged to detect a toner image on the image carrier, and at least arranged to contact the image carrier opposite to the toner image detector across the image carrier. An image forming apparatus comprising one opposing means includes an opposing means contacting / separating means for allowing the opposing means and the image carrier to contact and separate.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus includes a cleaning unit that cleans the toner image detection unit, and a drive source that drives the facing unit contacting / separating unit drives the cleaning unit. It is the same as the driving source to be operated.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the facing unit contacts the image carrier only when a toner image is detected by the toner image detecting unit.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the facing unit is disposed only at a position facing the toner image detecting unit via the image carrier. It is provided.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the toner image detecting means and the opposing means are more in the moving direction of the image carrier than the transfer means. It is arranged on the upstream side.

  A sixth aspect of the present invention is the image forming apparatus according to any one of the first to fifth aspects, further comprising a transfer unit contacting / separating unit that allows the transfer unit and the image carrier to be contacted and separated. The driving source for driving the facing unit contacting / separating unit is the same as the driving source for driving the transferring unit contacting / separating unit.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the image carrier is an intermediate transfer member.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image carrier is a transfer conveyance body.

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the image carrier is a photosensitive belt.

According to the present invention, a novel image forming apparatus can be realized and provided by solving the above problems. The effects for each claim are as follows.
According to the first aspect of the present invention, the facing means and the endless belt-like image carrier can be contacted and separated by the facing means contacting / separating means, so that the endless belt-like image carrier is damaged, Since sticking can be prevented, it is possible to perform highly reliable, easy and accurate density control and position control.

  According to the second aspect of the present invention, the cleaning unit can be driven in synchronism with and interlocking with the opposing unit contacting / separating unit, so that the toner image detecting unit can be detected without being contaminated. At the same time, those drive sources can be reduced to one.

  According to the third aspect of the present invention, the opposing means contacts the endless belt-like image carrier only when the toner image detecting means detects the toner image through the opposing means contacting / separating means. Since it is possible to minimize the contact time of the opposing means to the carrier, it is possible to more reliably prevent scratches and sticking to the endless belt-like image carrier. Thus, accurate density control and position control can be performed.

  According to the fourth aspect of the present invention, the opposing means should be detected by the toner image detecting means by being disposed only at a location facing the toner image detecting means via the endless belt-like image carrier. It is possible to correct unevenness or the like of only the endless belt-shaped image carrier, and it is possible to minimize the contact point of the facing means to the endless belt-shaped image carrier. Since scratches and sticking to the image carrier can be prevented more reliably, it becomes possible to perform density control and position control more reliably, easily and accurately.

  According to the fifth aspect of the present invention, since the facing means and the endless belt-like image carrier can be contacted and separated by the facing means contacting / separating means, an image during normal image formation may be disturbed. 5. The invention according to claim 1, wherein the toner image detecting means and the facing means are arranged upstream of the transfer means in the moving direction of the endless belt-like image carrier. The effect of.

  According to the sixth aspect of the present invention, with the above configuration, it is sufficient that the facing means is in contact with the endless belt-like image carrier only when the toner image is detected by the toner image detecting means, and is synchronized with the facing means contacting / separating means. It is possible to drive the transfer means contacting / separating means in conjunction with each other and to reduce the number of drive sources to one.

According to the invention described in claim 7, the effect of the invention described in any one of claims 1 to 6 can be obtained in the image forming apparatus in which the image carrier is an intermediate transfer member.
According to the invention described in claim 8, the effect of the invention described in any one of claims 1 to 4 can be obtained in the image forming apparatus in which the image carrier is a transfer carrier.
According to the ninth aspect of the present invention, the effect of the first aspect of the present invention can be obtained with an image forming apparatus in which the image carrier is a photosensitive belt.

1 is a schematic front sectional view of an image forming apparatus showing Embodiment 1. FIG. FIG. 3 is a perspective view of a main part of a sensor facing member contacting / separating mechanism according to Embodiment 1. It is a side view explaining the shape and dimension of a sensor facing member. FIG. 6 is a diagram illustrating a toner shape factor SF-1 used in the image forming apparatus of the present embodiment. FIG. 6 is a diagram illustrating a toner shape factor SF-2 used in the image forming apparatus of the present embodiment. FIG. 6 is a perspective view of a main part showing a first modification of the first embodiment. FIG. 10 is a simplified front view of a main part showing a second modification of the first embodiment. 6 is a schematic front sectional view of an image forming apparatus showing Embodiment 2. FIG. 5 is a schematic front sectional view of an image forming apparatus showing Embodiment 3. FIG.

  Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. In each embodiment and the like, components (members and components) having the same function and shape are described once unless they are confused, and the description thereof is omitted by giving the same reference numerals. When quoting and explaining constituent elements such as published patent gazettes, the reference numerals are shown in parentheses to distinguish them from those of the embodiments. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following embodiments and the like are examples of the best embodiment of the present invention and do not limit the scope of the claims.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram illustrating a color image forming apparatus according to the first embodiment. In the present embodiment, an example in which an endless belt-like image carrier that carries a toner image is used as an intermediate transfer member, and more specifically, an intermediate transfer belt 10 is used as an intermediate transfer member. The intermediate transfer belt 10 as an intermediate transfer member is a broad image carrier because it carries a toner image.
The color image forming apparatus shown in FIG. 1 includes four image forming units (or image forming units) that perform image formation with yellow toner, magenta toner, cyan toner, and black toner in this order from left to right in FIG. 2 is a color image forming apparatus of a tandem / intermediate transfer system arranged side by side below the transfer belt 10.
In the figure, by adding a subscript “a” to the components around the image forming unit relating to yellow toner, and attaching a subscript “b” to the components around the image forming unit relating to magenta toner, The components around the image forming means relating to the cyan toner are indicated by a suffix “c”, and the components around the image forming means relating to the black toner are indicated separately by attaching a suffix “d”. Yes. In the following, the components around each image forming unit are the same except that the toner color is different. Therefore, in order to simplify the explanation, except for the developing unit, the above numerals are omitted from the Arabic numerals. The description will be made generically with reference numerals (hereinafter, the same applies to the image forming apparatus of each embodiment).

  As shown in FIG. 1, the image forming apparatus according to the present embodiment includes a photoreceptor 1, and a photoreceptor cleaning unit 2 including a cleaning blade 3 as a cleaning unit around the photoreceptor 1, not shown. A neutralizing unit, a charger 4 as a charging unit, an exposure unit 5, a developing unit to be described later, an intermediate transfer belt 10 and the like are arranged. The exposure unit 5 adjusts the amount of light based on resistance detection information of the intermediate transfer belt 10 described later. The developing means includes four developing units, a yellow developing unit 6, a magenta developing unit 7, a cyan developing unit 8, and a black developing unit 9.

  When forming a full-color image, the surface of the photoreceptor 1 from which residual charges have been removed by a charge eliminating unit (not shown) is uniformly charged by the charger 4. Next, exposure light such as a laser is irradiated by the exposure means 5 based on the image information, and an electrostatic latent image is formed on the surface of the uniformly charged photoreceptor 1. The electrostatic latent image formed on the photoreceptor 1 is made visible by being supplied with toner of each color and developed in order by a yellow developing unit 6, a magenta developing unit 7, a cyan developing unit 8, and a black developing unit 9. An image (toner image) is formed, and a primary transfer bias is applied to a primary transfer bias roller 11 as a primary transfer unit via a primary transfer current applying unit 101 and a power source unit (not shown). The visible images of the respective colors are sequentially superimposed and transferred onto the intermediate transfer belt 10 running in the direction of the arrow in FIG. 1, thereby forming a full color image (toner image).

The transfer paper 25 as a sheet-like recording medium is separated one by one by a paper feed roller 26 as a sheet feeding means and a separating means (not shown) disposed in the sheet feeding device 31 and is transferred to a transfer paper conveying roller 27. And the tip of the registration roller 28 is temporarily stopped by the nip portion of the registration roller 28 to correct the oblique displacement, and then the tip of the four-color superimposed image on the surface of the intermediate transfer belt 10 is moved to the secondary transfer position. The paper is fed from the registration roller 28 in accordance with the arrival timing. The four-color superimposed image on the intermediate transfer belt 10 is a secondary transfer roller as a secondary transfer unit to which a predetermined voltage is applied via a secondary transfer position, that is, a power source (not shown) and a secondary transfer current application unit 102. 21 is collectively transferred to the transfer paper 25.
The four-color superimposed image transferred to the transfer paper 25 is discharged to a fixing means 30 along a fixing inlet guide 44 after being discharged by a discharging means (not shown), and heated and pressurized by the fixing means 30 to be fixed. The paper is discharged by a paper discharge roller 32 to a paper discharge tray (not shown).

Hereinafter, the configuration of the present embodiment will be further described in detail. The intermediate transfer belt 10 is stretched over and stretched between the primary transfer bias roller 11, the secondary transfer counter roller 12, the driven roller 14, the driven roller 15, and the belt cleaning counter roller 13. A bearing (not shown) of the belt cleaning counter roller 13 is engaged with one end of a compression spring 13 for applying a predetermined tension to the intermediate transfer belt 10, and the roller 13 is always attached to the left in the drawing. It is energized. Each primary transfer bias roller 11 is brought into contact with the back surface of the intermediate transfer belt 10 by a roller pressing means 29 made of a compression spring or the like, and the surface of the intermediate transfer belt 10 is in contact with the photoreceptor 1 via the intermediate transfer belt 10. It is urged in the direction to contact and press.
The secondary transfer counter roller 12 also serves as a drive roller for the intermediate transfer belt 10 and is connected to a drive motor (not shown) via a drive force transmission means such as a gear train. The intermediate transfer belt 10 is adjusted and set so as to run and drive at a process speed of 150 mm / sec by the drive motor (not shown).
The rollers 11, 13, 14, and 15 including the secondary transfer counter roller 12 are rotatably supported and supported from both sides of the intermediate transfer belt 10 by intermediate transfer belt unit side plates (not shown).

  The primary transfer bias roller 11 is disposed at a contact portion between the photosensitive drum 1 provided for each image forming unit and the intermediate transfer belt 10 facing the primary transfer bias roller 11. A predetermined transfer bias is applied via the primary transfer current applying unit 101. In this embodiment, + 1800V is set to be applied.

The intermediate transfer belt 10 is made of a single layer or a plurality of layers of resins such as PVDF (polyvinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PAI (polyamideimide), PC (polycarbonate), and the like. The conductive material such as carbon black is dispersed, the volume resistivity is adjusted to 10 ⁸ to 10 ¹² Ωcm, and the surface resistivity is adjusted and set to be in the range of 10 ⁹ to 10 ¹³ Ω / □. ing. If necessary, a release layer may be coated on the surface of the intermediate transfer belt 10. Materials used for the coating include ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PEA (perfluoroalkoxy fluororesin), FEP (four-fluorocarbon). Fluorine resin such as ethylene fluoride-propylene hexafluoride copolymer) or PVF (vinyl fluoride) can be used, but is not limited thereto.
The method of manufacturing the intermediate transfer belt 10 includes a casting method, a centrifugal molding method, and the like, and the surface thereof may be polished as necessary.

  If the volume resistivity of the intermediate transfer belt 10 exceeds the above-described range, the bias required for transfer increases, which increases the power supply cost. Further, since the charging potential of the intermediate transfer belt 10 becomes high and the self-discharge becomes difficult in the transfer process, the transfer paper peeling process, etc., it is necessary to provide a static eliminating means. Also, if the volume resistivity and surface resistivity are below the above ranges, the charge potential decays quickly, which is advantageous for static elimination by self-discharge, but toner scatter occurs because the current during transfer flows in the surface direction. End up. Therefore, the volume resistivity and the surface resistivity of the intermediate transfer belt 10 in the present embodiment are preferably within the above ranges.

  The volume resistivity and the surface resistivity are measured by connecting an HRS probe (inner electrode diameter 5.9 mm, ring electrode inner diameter 11 mm) to a high resistivity meter (Mitsubishi Chemical Corporation: Hiresta IP) and measuring the volume resistivity. In this case, a voltage of 100 V was applied to the front and back of the intermediate transfer belt 10, and in the case of measurement of the surface resistivity, a voltage of 500 V was applied to the front and back of the intermediate transfer belt 10, and measured values after 10 seconds were used.

With reference to FIGS. 1-3, the characteristic part of this embodiment is demonstrated.
As shown in FIGS. 1 and 2, the toner image detection for detecting the toner image on the intermediate transfer belt 10 in order to correct the density of the toner image formed on the intermediate transfer belt 10 or to correct the positional deviation. Toner image detection sensors 46 as means are arranged in parallel along the main scanning direction Y at different locations in the main scanning direction Y corresponding to the width direction of the intermediate transfer belt 10. In FIG. 2, the intermediate transfer belt 10 is indicated by a two-dot chain line.
As shown in an enlarged view in FIG. 2, in this embodiment, a plurality of (three in this embodiment for simplicity of explanation) toner image detection sensors 46 extend along the main scanning direction Y. The optical sensor unit 45 is configured to be fixed to the upper end of 47. The optical sensor unit 45 is disposed to face the belt surface in the lower running area of the intermediate transfer belt 10 vertically downward. In the drawing of the substrate 47, the left and right end portions are fixed to a pair of side plates (not shown) which are stationary members of the apparatus main body.

  In the image forming apparatus of this embodiment, a toner image correction pattern is formed on the intermediate transfer belt 10, and each toner image detection sensor 46 detects the toner image. That is, the image forming apparatus according to the present embodiment forms a predetermined resist pattern on four image forming units that perform image formation with yellow toner, magenta toner, cyan toner, and black toner, respectively, as in Patent Document 1, for example. An optical sensor unit 45 serving as a pattern detection means for detecting a resist pattern formed by the resist pattern generation means for generating a resist pattern in the exposure means and the image forming means and transferred onto the intermediate transfer belt 10. Misalignment correcting means for correcting the misalignment based on the result detected by the optical sensor unit 45. Among these, various known configurations can be adopted as the resist pattern generating means and the positional deviation correcting means.

  The toner image detection sensor 46 includes a reflection type optical sensor including a light emitting element and a light receiving element. The toner image detection sensor 46 is a well-known sensor unit having a lens surface 46a on the upper side in the drawing. More specifically, in this embodiment, the optical sensor unit 45 is provided with three toner image detection sensors 46 for the sake of simplicity of explanation. Among them, for example, the sensors 46 at both ends in the main scanning direction Y include the resist pattern. The sensor 46 located between them is used to detect a toner density control pattern. The toner image detection sensor 46 uses, for example, an LED (light emitting diode) as a shipping element and a PD (photodiode) or a phototransistor as a light receiving element. Then, the light receiving element receives the reflected light irradiated from the light emitting element and specularly reflected on the surface of the intermediate transfer belt 10. A plane including the optical axis of the light emitting element and the optical axis of the light receiving element is arranged to be parallel to the width direction of the belt.

  At a position facing the toner image detection sensor 46 with the intermediate transfer belt 10 interposed therebetween, a plurality of sensor facing members 49 (three corresponding to the toner image detection sensor 46 in the present embodiment) as opposing means are arranged. Has been. Each sensor facing member 49 is fixed to the sensor facing shaft 48 arranged in parallel with the main scanning direction Y in the same phase. Both ends of the sensor facing shaft 48 are rotatably supported by bearings (not shown) disposed on the side plate pair (not shown). The sensor facing member 49 has a phase opposite to that of the sensor facing contact portion 49a which is a large-diameter portion having a relatively large protruding amount from the sensor facing shaft 48 so as to contact the back surface of the intermediate transfer belt 10. The non-contact portion 49b is a small-diameter portion that is formed on the opposite side and does not contact the back surface of the intermediate transfer belt 10, and has a substantially triangular cam shape.

  As described above, the sensor facing member 49 is intermittently connected to the back surface of the intermediate transfer belt 10 only at the positions facing the toner image detection sensors 46 across the intermediate transfer belt 10 at three different positions in the main scanning direction Y. The sensor facing abutment portion 49a, which is a sliding portion, is arranged to minimize. Further, as shown in FIG. 1, the sensor facing member 49 and the optical sensor unit 45 are arranged on the upstream side of the intermediate transfer belt 10 in the arrow moving direction in the drawing with respect to the secondary transfer roller 21 as the secondary transfer means. Yes.

In FIG. 2, reference numeral 50 denotes a sensor facing member contacting / separating mechanism as a facing means contacting / separating means that allows the sensor facing member 49 and the back surface of the intermediate transfer belt 10 to contact and separate from each other. The sensor facing member contact / separation mechanism 50 includes a sensor facing shaft 48, a drive motor 51 as a drive source connected to one end of the sensor facing shaft 48, and a home position sensor (not shown) that detects the home position of the sensor facing member 49. It consists of and.
The drive motor 51 is composed of, for example, a stepping motor, and is fixed to the side plate (not shown). The home position sensor (not shown) detects the phase of the sensor facing member 49, and is a light shielding plate (not shown) formed at one end or the other end of the sensor facing shaft 48 so as to protrude in the centrifugal direction. And a transmissive optical sensor disposed so as to sandwich the light shielding plate. For example, when the non-contact portion 49b of the sensor facing member 49 occupies a position facing the back surface of the intermediate transfer belt 10, the home position It is comprised so that it may detect as.

  The control configuration of this embodiment will be briefly described. Each toner image detection sensor 46 and the above-described home position (not shown) are connected to the input side of a control means including a well-known microcomputer having a CPU, ROM, RAM, internal timer, etc. (not shown). It is connected to the output side of the control means. The CPU of the control unit controls the operation of the drive motor 51 based on each toner image detection sensor 46, a detection signal from a home position (not shown), an operation program called from the ROM of the control unit, and the like.

  Next, the operation of the sensor facing member contact / separation mechanism 50 will be briefly described. When the sensor facing shaft 48 is rotated by the drive motor 51, the sensor facing contact portion 49 a integrated with the sensor facing shaft 48 can be brought into contact with and separated from the back surface of the intermediate transfer belt 10. That is, a predetermined number of pulses is applied to the drive motor 51 via a motor driver (not shown) in accordance with a command from the control means, so that the drive motor 51 is driven to rotate, thereby causing the sensor facing shaft 48 to rotate. The sensor facing contact portion 49a of the sensor facing member 49 contacts the back surface of the intermediate transfer belt 10 and occupies the contact position. Further, when the predetermined number of pulses or the number of reverse pulses is applied to the drive motor 51, the sensor facing shaft 48 further rotates or reversely rotates so that the non-contact portion 49 b of the sensor facing member 49 is removed from the back surface of the intermediate transfer belt 10. It occupies a separated non-contact position.

When the intermediate transfer belt 10 is rotated in a state where the sensor facing contact portion 49a and the back surface of the intermediate transfer belt 10 are in contact with each other, the sensor facing contact portion 49a and the intermediate transfer belt 10 are caused to slide by friction and friction. The contact portion 49a may be charged. Then, since the toner image carried on the intermediate transfer belt 10 passes over the charged sensor facing contact portion 49a, the toner image may be disturbed. When the optical sensor unit 45 (sensor detection unit) is upstream of the secondary transfer position as in the present embodiment, the toner image transferred to the transfer paper is disturbed, resulting in an image defect.
Further, in an electrophotographic image forming apparatus, when an image having a low image area is continuously formed, the toner deteriorates, and thus it is necessary to discharge the deteriorated toner. In this case, since the secondary transfer roller 21 that is a transfer unit is in contact with the intermediate transfer belt 10 while being in contact with the intermediate transfer belt 10, the secondary transfer roller 21 is contaminated with the discharged toner. Therefore, as in Modification 2 shown in FIG. The secondary transfer roller 21 is separated from the intermediate transfer belt 10. When the contact / separation drive of the secondary transfer roller 21 to the intermediate transfer belt 10 and the contact / separation drive of the sensor facing member 49 to the back surface of the intermediate transfer belt 10 are the same, Since the opposing member 49 comes into contact with the back surface of the intermediate transfer belt 10, there is a problem that the intermediate transfer belt 10 is easily damaged or stuck.
From the above, it is desirable that the sensor facing member 49 is in contact with the back surface of the intermediate transfer belt 10 only during toner image correction or positional deviation correction, that is, only when a toner image is detected by the toner image detection sensor 46.

  Hereinafter, examples of the sensor facing shaft 48 and the sensor facing member 49 will be supplementarily described. Examples of the material of the sensor facing shaft 48 and the sensor facing member 49 include general resin materials such as ABS resin, polycarbonate resin (PC), and polyacetal resin (POM), or free-cutting steel such as SUS and SUM. Preferably, SUM (free cutting steel) is employed as the sensor facing shaft 48 and ABS resin is employed as the sensor facing member 49 for fixing. Further, for example, nylon having good slidability may be implanted on the outer peripheral surface of the sensor facing abutting portion 49a which is a surface in contact with the back surface of the intermediate transfer belt 10.

  The sensor facing contact portion 49a that forms the sensor detection surface in contact with the back surface of the intermediate transfer belt 10 needs to have high hardness and high accuracy. However, if the entire sensor facing member 49 together with the sensor facing shaft 48 is made of SUM (free-cutting steel), both the man-hour and the cost are required. Therefore, a high hardness SUM (free-cutting steel) is used as the sensor facing shaft 48, and the sensor facing contact portion 49a which is a portion in contact with the back surface of the intermediate transfer belt 10 uses ABS resin which is easy to obtain accuracy and is relatively inexpensive. It was decided. In addition, since the back surface of the intermediate transfer belt 10 and the outer peripheral surface of the sensor facing contact portion 49a slide in contact with each other, the back surface of the intermediate transfer belt 10 may be damaged and the image may be disturbed. Planted with good nylon.

Details of the sensor facing shaft 48 and the sensor facing member 49 will be described with reference to FIG. In FIG. 3, the sensor facing member 49 is simply illustrated so as to continuously exist along the main scanning direction Y for the sake of explanation and simplification of the drawing.
The diameter of the sensor facing shaft 48 is preferably about 6 mm, and the outer diameter of the sensor facing contact portion 49a is preferably about 9 mm. A sensor detection surface of the sensor facing contact portion 49a facing the toner image detection sensor 46 is provided with a plane of about 6 mm along the moving direction of the intermediate transfer belt 10 orthogonal to the main scanning direction Y. The width dimension of the sensor facing member 49 positioned at both ends of the sensor facing shaft 48 along the main scanning direction Y is about 300 mm. In the width direction of the sensor facing shaft 48, as shown in the following formula (3), the main scanning direction It is advisable to apply a “Tyco” shape so that the shape protrudes upward in the figure as it goes toward the center of Y.
H = 4.75− (0.25 / 156 ^1.5 ) × | L−167.3 | ^1.5 (3)
Here, H represents the distance from the center of the sensor facing shaft 48 to the outer peripheral surface of the non-contact portion 49b of the sensor facing member 49, and L represents the distance along the main scanning direction Y from one end of the sensor facing shaft 48.

Since the strength is required, the diameter of the sensor facing shaft 48 is about φ6 mm, and the outer diameter of the sensor facing contact portion 49a is about φ9 mm. Further, the area of the sensor detection surface is about 6 mm because it is flat and needs a margin for the intermediate transfer belt 10 to be stable.
The length of the sensor facing shaft 48 in the width direction (main scanning direction Y) is as long as possible so that the intermediate transfer belt 10 is stabilized. However, the length of the width of the intermediate transfer belt 10 needs to be shorter. Further, since the center portion of the sensor facing shaft 48 is bent due to its own weight, it is better to have a “taiko” shape in order to absorb and correct the bending.

  In FIG. 1, reference numeral 19 denotes a belt cleaning unit that cleans the intermediate transfer belt 10. The belt cleaning unit 19 is provided with a cleaning blade 20 made of urethane rubber as a cleaning means, and the tip of the cleaning blade 20 is pressed against the surface of the intermediate transfer belt 10 to dam the toner and clean it. It has become.

In order to facilitate cleaning of the intermediate transfer belt 10, a solid lubricant 155 molded from a raw material containing a fatty acid metal salt (A) and an inorganic lubricant (B) is used as a lubricant application member 152 as a lubricant application means. To apply or adhere to the intermediate transfer belt 10.
The fatty acid metal salt (A) has a linear hydrocarbon structure, for example, contains at least one fatty acid selected from stearic acid, palmitic acid, myristic acid, oleic acid, zinc, aluminum, calcium , Fatty acid metal salts containing at least one metal selected from magnesium and lithium. In particular, zinc stearate is the most preferable material in terms of cost, quality stability, and reliability because it is produced on an industrial scale and has been used in many fields. However, the higher fatty acid metal salts that are generally used industrially are not the simple substance composition of the name, but include other fatty acid metal salts, metal oxides, and free fatty acids that are more or less similar. Fatty acid metal salts in form are no exception.

  The inorganic lubricant (B) refers to an inorganic compound that cleaves and lubricates itself or causes internal slip. Specific examples include talc, mica, boron nitride, molybdenum disulfide, tungsten disulfide, kaolin, smectite, hydrotalcite compound, calcium fluoride, graphite, plate-like alumina, sericite, and synthetic mica. However, it is not limited to this. In particular, boron nitride has hexagonal mesh surfaces with tightly intermingled atoms overlapping at a wide interval, and the force acting between the layers is only the weak van der Waals force. Preferably used. These inorganic lubricants may be surface-treated as necessary for the purpose of imparting hydrophobicity.

  A small amount of these lubricants are supplied to the surface of the intermediate transfer belt 10 in the form of powder. As a specific method, the lubricant is applied in blocks (lumps) by a lubricant application member 152 such as a brush. There are a method of scraping and applying a solid-molded lubricant, a method of supplying it by adding it externally to the toner, and the like. However, when the lubricant is supplied externally to the toner, the supply amount depends on the output image area and cannot always be supplied to the entire surface of the intermediate transfer belt. When the lubricant is to be supplied stably over the entire surface of the transfer belt, a method of scraping and applying the solid lubricant 155 with the brush-like lubricant application member 152 as in this embodiment is preferable.

  In order to scrape the solid lubricant 155 with the brush-like lubricant application member 152, the lubricant pressurizing means 153, which is an elastic body such as a spring, causes the solid lubricant 155 to be brushed with a force of 1 to 4N. It is pressed against the application member 152. The width of the solid lubricant 155 (which is also the dimension in the axial direction of the photosensitive member 1 perpendicular to the paper surface or the dimension in the width direction of the intermediate transfer belt 10) needs to be set wider than the image width. . The width of the brush-like lubricant application member 152 needs to be larger than the width of the solid lubricant 155 in order to evenly scrape the solid lubricant 155.

The secondary transfer roller 21 is configured by coating an elastic body such as urethane adjusted to a resistance value of 10 ⁶ to 10 ¹⁰ Ω with a conductive material on a metal core bar such as SUS. Here, if the resistance value of the secondary transfer roller 21 exceeds the above range, it becomes difficult for the current to flow. Therefore, a higher voltage must be applied in order to obtain the required transfer property, resulting in an increase in power supply cost. . In addition, since a high voltage is applied, a discharge occurs in the gap before and after the nip of the transfer portion, so that white spots are lost on the halftone image due to the discharge. On the contrary, if the resistance value of the secondary transfer roller 21 is below the above range, the transferability between the multi-color image portion (for example, three-color superimposed image) and the single-color image portion existing on the same image cannot be achieved. This is because when the resistance value of the secondary transfer roller 21 is low, a sufficient current flows to transfer the monochrome image portion at a relatively low voltage. However, it is optimal for the monochrome image portion to transfer the multiple color image portion. This is because a voltage value higher than the voltage is required, and setting a voltage that can transfer a plurality of color image portions causes an excessive transfer current in a single color image, resulting in a decrease in transfer efficiency.
The resistance value of the secondary transfer roller 21 is measured by installing the secondary transfer roller 21 on a conductive metal plate and applying a load of 4.9 N on one side (total of 9.8 N on both sides) to both ends of the core metal. In this state, it was calculated from the value of the current flowing when a voltage of 1000 V was applied between the metal core and the metal plate.
The secondary transfer roller 21 is given a driving force by a driving gear (not shown), and its peripheral speed is adjusted and set to be substantially the same as the peripheral speed of the intermediate transfer belt 10. .

  A predetermined voltage is applied to the secondary transfer roller 21 via a power source (not shown) and a secondary transfer current applying unit 102. The secondary transfer is controlled with a constant current, and in the present embodiment, the set value is +30 μA.

The toner used in this embodiment is a polymerized toner produced by a polymerization method, and a polymerized toner having a shape factor SF-1 of 100 to 180 and a shape factor SF-2 of 100 to 180 is used. preferable.
FIG. 4 is a diagram schematically showing the shape of the toner for explaining the shape factor SF-1, and FIG. 5 is a diagram for explaining the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner is a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the SF-2 value increases, the unevenness of the toner surface becomes more prominent.

Specifically, the shape factors SF-1 and SF-2 are measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.) and using this image analysis device (LUSEX3: manufactured by Nireco). It was introduced and analyzed and calculated.
When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered and the cleaning property when attached to the transfer means is also lowered, which is not preferable.
The toner particle size is preferably in the range of 4 to 10 μm in terms of volume average particle size. When the particle size is smaller than this, it becomes a cause of background stains during development, fluidity is deteriorated, and further, it tends to agglomerate. On the other hand, when the particle size is larger than this, a high-definition image cannot be obtained due to toner scattering or resolution deterioration. In this embodiment, a toner having a volume average particle diameter of 6.5 μm within the range of 4 to 10 μm was used.

  According to this embodiment, it is needless to say that the above-described effects according to claims 1, 3 to 5, and 7 corresponding to the above configuration and operation are achieved.

(Modification 1 of Embodiment 1)
When the sensor facing member 49 is brought into contact with the intermediate transfer belt 10 as in the first embodiment shown in FIG. 2, the distance between the intermediate transfer belt 10 and the toner image detection sensor 46 becomes short, so that the toner image. The detection sensor 46 is easily affected by the scattering of toner, the lens surface 46a, which is the detection surface of the toner image detection sensor 46, becomes dirty due to toner adhesion, and toner images such as a toner image correction pattern and a resist pattern can be detected and read. There is a problem that can not be accurately. Further, in order to solve this problem, if it is considered to drive automatically by adding a cleaning means, a new drive source is required. Therefore, Modification 1 of Embodiment 1 was created to solve these problems.

A first modification will be described with reference to FIG. In the drawing, the illustration of the intermediate transfer belt 10 is omitted.
As compared with the first embodiment shown in FIGS. 1 to 3, Modification 1 is a cleaning unit provided with a cleaning brush 54 a for cleaning the lens surface 46 a of the toner image detection sensor 46 as shown in FIG. 6. The cleaning member 54 (three in correspondence with the three toner image detection sensors 46 in this embodiment) is newly used, and the opposing member driving mechanism 50 (opposing means contacting / separating means) provided with the driving motor 51 is used. Instead, as will be described later, a drive motor 57 is provided as a drive source of the cleaning means for reciprocating the cleaning member 54 in the main scanning direction Y, and the opposing member 49 is synchronized with and synchronized with the drive operation of the cleaning member 54. The main difference is that a driving force transmission mechanism 56 for making contact with and separating from the intermediate transfer belt 10 is used.
The configuration of the first modification other than this difference is the same as that of the first embodiment. In other words, the driving force transmission mechanism 56 has a function and configuration that can be read as the opposing member contacting / separating mechanism 56 as the driving force transmitting means of the opposing means contacting / separating means.
That is, the first modification is a configuration in which the sensor facing member 49 is driven to contact and separate from the back surface of the intermediate transfer belt 10 using a drive motor 57 as a driving source of the cleaning member 54. The drive source and the drive source of the cleaning means are the same.

  The cleaning member 54 is installed so that a cleaning brush 54 a provided at the lower end of the tip thereof can contact the lens surface 46 a above the toner image detection sensor 46. The cleaning brush 54a is configured by a base fabric woven from a polyester base yarn. The three cleaning members 54 are fixed to the upper part of the movable plate 55 supported so as to be reciprocally movable in the main scanning direction Y by a guide member (not shown) provided between the side plates (not shown). A cleaning unit 53 that can move back and forth in the main scanning direction Y is configured together with the movable plate 55. In the drawing of the movable plate 55, the right back side end portion has a pressure contact portion 55a of the movable plate 55 formed by a compression spring 55A interposed between a fixed member fixed to the side plate (not shown) on the back side in the drawing. In the figure, it is urged in a direction that always moves to the left front side, that is, a direction that presses against the contour peripheral surface of the cam 58.

The drive motor 57 is a stepping motor, for example. A substantially triangular plate-shaped cam 58 having a large diameter portion and a small diameter portion is fixed to the output shaft of the drive motor 57. A pressure contact portion 55a of the movable plate 55 that is urged by the compression spring 55A so as to always move toward the front side in the drawing is in sliding contact with the contour peripheral surface of the cam 58.
The opposing member contact / separation mechanism 56 includes a gear 59 fixed coaxially with the output shaft of the drive motor 57, a gear 60 meshing with the gear 59, and a gear shaft 60a of the gear 60 fixed to the sensor opposing shaft 48. It is comprised from the bevel gear 61 which meshes with each other fixedly provided at one end. The gear 59 and the gear 60 are spur gears, and the bevel gear 61 is a straight bevel gear.

  The control configuration of this modification will be briefly described. Each toner image detection sensor 46 and the above-described home position (not shown) are connected to the input side of the control means including the microcomputer having the same configuration as in the first embodiment, and the drive motor 57 is connected to the output side of the control means. ing. The CPU of the control means controls the operation of the drive motor 57 based on each toner image detection sensor 46, a detection signal from a home position (not shown) and an operation program called from the ROM of the control means.

Next, the operation of the main part of Modification 1 will be briefly described. Similar to the first embodiment, the cam 58 rotates against the urging force of the compression spring 55 </ b> A by applying a predetermined number of pulses to the drive motor 57. The rotation of the cam 58 causes the circumferential surface of the large diameter portion and the small diameter portion of the cam 58 to come into sliding contact with the press contact portion 55a sequentially as shown in FIG. 6, so that the cleaning unit 53 reciprocates in the main scanning direction Y. Thus, the lens surface 46a of each toner image detection sensor 46 is cleaned by the cleaning brush 54a.
On the other hand, in synchronism with and in conjunction with the cleaning operation, the rotational driving force of the drive motor 57 is transmitted to the sensor facing shaft 48 via the facing member contacting / separating mechanism 56, so that the sensor integrated with the sensor facing shaft 48 is integrated. The opposing contact portion 49a can be brought into contact with and separated from the back surface of the intermediate transfer belt 10. That is, as in the first embodiment, the drive motor 57 is controlled by the CPU of the control means (not shown) based on the output signal from the home position (not shown), so that the sensor facing shaft 48 rotates and the sensor faces. The sensor facing contact portion 49a of the member 49 contacts the back surface of the intermediate transfer belt 10 and occupies the contact position. Further, by applying a predetermined number of pulses to the drive motor 57, the sensor facing shaft 48 further rotates, and the non-contact portion 49b of the sensor facing member 49 is moved away from the back surface of the intermediate transfer belt 10. Will be occupied.

  According to the first modification, it is needless to say that the effects described above according to claims 2 and 7 corresponding to the above configuration and operation are achieved.

(Modification 2 of Embodiment 1)
When the toner image is detected by the toner image detection sensor 46 (when the toner image is adjusted), there is a problem that the transfer unit is contaminated with an image for adjusting the toner image such as a toner image correction pattern because the sheet is not passed. Therefore, the image forming apparatus of FIG. 1 has a transfer unit contacting / separating unit that operates the secondary transfer roller 21 (secondary transfer unit) away from the intermediate transfer belt 10 (image carrier) during toner image adjustment. It is common to do. In this modification, the driving means transmitting means of the opposing means contacting / separating means is configured by using the transfer means contacting / separating means.

Modification 2 will be described with reference to FIG.
In the second modification, compared to the first embodiment, the transfer roller contact as a transfer means contact / separation means that allows the secondary transfer roller 21 (transfer means) and the intermediate transfer belt 10 (image carrier) to contact and separate from each other is possible. Instead of the sensor facing member contact / separation mechanism 50 having a drive motor 51 as a drive source, a drive motor 71 as a drive source for the transfer roller contact / separation mechanism 70 is provided, The main difference is that a driving force transmission mechanism 76 that moves the opposing member 49 in and out of contact with the intermediate transfer belt 10 in synchronization with and interlocked with the contact and separation operation of the separation mechanism 70 is mainly used.
The configuration of the second modification other than this difference is the same as that of the first embodiment. In other words, the driving force transmission mechanism 76 has a function and configuration that can be read as the opposing member contacting / separating mechanism 76 as the driving force transmitting means of the opposing means contacting / separating means.
That is, in the second modification, the sensor facing member 49 is driven to contact and separate from the back surface of the intermediate transfer belt 10 via the driving force transmission mechanism 76 using the drive motor 71 of the transfer roller contact / separation mechanism 70. The driving source of the opposed unit contacting / separating unit and the driving source of the transfer unit contacting / separating unit are the same.

The transfer roller contact / separation mechanism 70 mainly includes a drive motor 71, a contact / separation cam 72, a contact / separation lever 73, a support shaft 74, and a tension spring 75.
The drive motor 71 is composed of, for example, a stepping motor. A substantially triangular plate-shaped contact / separation cam 72 having a large-diameter portion and a small-diameter portion is fixed to the output shaft of the drive motor 71. The secondary transfer roller 21 is attached in a direction in which it is pressed against the secondary transfer counter roller 12 via the intermediate transfer belt 10 by a compression spring (not shown) whose one end is locked to the bearing portion of its own shaft 21a. It is energized. In the side plate pair (not shown), guide grooves that enable a movement operation when both ends of the shaft 21a of the secondary transfer roller 21 are brought into contact with and separated from the secondary transfer counter roller 12 via the intermediate transfer belt 10. Is formed. The support shaft 74 is swingably supported between the side plates (not shown) so as to swing the straight ruler-shaped contact / separation lever 73 in a swingable manner. On the contour peripheral surface of the contact / separation cam 72, the tension spring 75 locked between the side plate (not shown) and the center of the contact / separation lever 73 always swings counterclockwise around the support shaft 74 in the drawing. One end portion 73a of the contact / separation lever 73 biased so as to slide is in sliding contact.

The drive force transmission mechanism 76 includes a gear 71A fixed to the output shaft of the drive motor 71, a first idler gear 77 that meshes with the gear 71A, a second idler gear 78 that meshes with the first idler gear 77, and the second idler gear. 78 and an opposing member drive gear 79 that meshes with 78. The gear 71A, the first idler gear 77, the second idler gear 78, and the opposing member drive gear 79 are spur gears. The gear 71 </ b> A is fixed to the output shaft of the drive motor 71 that is coaxial with the shaft of the contact / separation cam 72. The facing member drive gear 79 is fixed to the sensor facing shaft 48.
In FIG. 7, the gear 71 </ b> A, the first idler gear 77, the second idler gear 78, and the opposing member drive gear 79 are simply shown. The gear number ratio of these gear trains is the sensor opposing contact portion 49 a of the sensor opposing member 49. Occupies a separated position away from the back surface of the intermediate transfer belt so that the secondary transfer roller 21 always occupies a position in pressure contact with the secondary transfer counter roller 12 via the intermediate transfer belt 10 and vice versa. When the secondary transfer roller 21 occupies a position separated from the secondary transfer counter roller 12 via the intermediate transfer belt 10, the sensor facing contact portion 49a occupies a contact position that contacts the back surface of the intermediate transfer belt. Is set.

  The control configuration of this modification is control using a drive motor 71 instead of the drive motor 57 as compared with that of the first embodiment, and those skilled in the art can easily understand from the first embodiment and the first modification. Since it can be implemented, further explanation is omitted.

Next, the operation of the main part of Modification 2 will be described. As in the first embodiment, the transfer roller contact / separation mechanism 70 operates by applying a predetermined number of pulses to the drive motor 71. As the drive motor 71 rotates, the contact / separation cam 72 rotates against the urging force of the tension spring 75. When the large-diameter portion of the contact / separation cam 72 lifts the one end 73 a of the contact / separation lever 73 by the rotation of the contact / separation cam 72, the contact / separation lever 73 is swung clockwise around the support shaft 74 in the drawing. As a result, the other end 73b of the contact / separation lever 73 pushes and moves the shaft 21a of the secondary transfer roller 21 against the biasing force of the compression spring (not shown), so that the secondary transfer roller 21 becomes the secondary transfer counter roller. Occupies a position spaced apart from 12.
At the same time, the rotational driving force of the driving motor 71 is transmitted to the sensor facing shaft 48 via the driving force transmission mechanism 76 in synchronization with and interlocking with the separation operation of the secondary transfer roller 21 by the transfer roller contact / separation mechanism 70. Thus, the sensor facing member 49 occupies the contact position when the sensor facing contact portion 49 a of the sensor facing member 49 contacts the back surface of the intermediate transfer belt 10.

On the other hand, when a predetermined number of pulses or the number of pulses for reverse rotation is further applied to the drive motor 71, the contact / separation cam 72 rotates as shown in FIG. When the sliding contact is made, the contact / separation lever 73 is swung counterclockwise around the support shaft 74 by the urging force of the tension spring 75, so that the other end 73b of the contact / separation lever 73 is subjected to secondary transfer. By separating from the shaft 21 a of the roller 21, the secondary transfer roller 21 occupies a position in contact with the secondary transfer counter roller 12 via the intermediate transfer belt 10 by a biasing force of a compression spring (not shown).
At the same time, the rotational driving force of the drive motor 71 is applied to the sensor facing shaft 48 via the driving force transmission mechanism 76 in synchronization with and interlocking with the contact operation of the secondary transfer roller 21 by the transfer roller contact / separation mechanism 70. By being transmitted, the non-contact portion 49b of the sensor facing member 49 is separated from the back surface of the intermediate transfer belt 10, so that the sensor facing member 49 occupies a separated position.

As described above, during normal sheet passing, if the sensor facing member 49 and the intermediate transfer belt 10 are in contact with each other, problems such as scratches / abrasion on the belt, vibration, abnormal noise, etc. may occur. It is better to separate the member 49 and the intermediate transfer belt 10 from each other.
On the other hand, since the toner image is not passed when the toner image is detected, the toner image adheres to the secondary transfer roller 21 and the transfer paper is soiled when the paper is passed immediately thereafter. It is better to keep 21 apart.
From the above two points, it is better to synchronize and interlock the contact / separation drive of the secondary transfer roller 21 and the contact / separation drive of the sensor facing member 49. Thereby, the drive source can be reduced by one by making the drive source the same and common.
According to the second modification, it is needless to say that the effects described above according to claims 6 and 7 corresponding to the above configuration and operation are achieved.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. The image forming apparatus shown in FIG. 8 is also based on the same technical idea as that of the first embodiment and the first modification described above, and thus has a configuration that exhibits essentially the same function even if there are some functional differences. The elements will be briefly described with the same reference numerals as those used in Embodiment 1 and Modification 1 unless there is a possibility of confusion. FIG. 1 is a schematic configuration diagram showing a color image forming apparatus according to the second embodiment. In the present embodiment, an example will be described in which an image carrier is a transfer conveyance body, and more specifically, an endless transfer conveyance belt 18 is used as a transfer conveyance body. The transfer / conveying belt 18 is an image carrier in a broad sense because it forms an image while carrying a sheet-like recording medium carrying a toner image.
In the color image forming apparatus shown in FIG. 8, four image forming units (or image forming units) that perform image formation with yellow toner, magenta toner, cyan toner, and black toner are transferred in this order from right to left in FIG. This is a tandem / direct transfer type color image forming apparatus arranged side by side above the conveying belt 18.
In the second embodiment, as will be described later, in comparison with the first embodiment, the tandem / direct transfer using the transfer conveyance belt 18 is used instead of the tandem / indirect transfer type color image forming apparatus using the intermediate transfer belt 10. It differs greatly in that it is a transfer type color image forming apparatus.

As shown in FIG. 8, the image forming apparatus according to the present embodiment includes a photoconductor 1, and a photoconductor cleaning unit including a cleaning blade 3 around the photoconductor 1 as shown in FIG. 2, a discharging means (not shown), a charger 4, an exposure means 5, a developing means (a yellow developing device 6, a magenta developing device 7, a cyan developing device 8, a black developing device 9), a transfer conveyance belt 18 and the like are arranged.
When forming a full-color image, the surface of the photoreceptor 1 from which residual charges have been removed by a charge eliminating unit (not shown) is uniformly charged by the charger 4. Next, exposure light such as a laser is irradiated by the exposure means 5 based on the image information, and an electrostatic latent image is formed on the surface of the uniformly charged photoreceptor 1. The electrostatic latent image formed on the photoreceptor 1 is made visible by being supplied with toner of each color and developed in order by a yellow developing unit 6, a magenta developing unit 7, a cyan developing unit 8, and a black developing unit 9. An image (toner image) is formed, and a transfer bias is applied to a transfer bias roller 23 serving as a transfer unit via a power source unit (not shown) and a transfer current application unit 103 in a toner image transfer unit in each image forming unit. As a result, a visible image of each color is transferred onto the transfer paper that is sucked and conveyed on the transfer conveyance belt 18 that runs in the direction of the arrow in FIG. 8, thereby forming a full-color image (toner image). The

The transfer paper 25 is separated one by one by a paper feed roller 26 of the sheet feeding device 31 and a separating means (not shown) and fed via a transfer paper transport roller 27. After the front end is temporarily stopped and the oblique deviation is corrected, the sheet is fed from the registration roller 28 toward the nip portion between the transfer conveyance belt 18 and the entrance roller 17 at a predetermined timing.
The four-color superimposed image transferred to the transfer paper 25 is discharged to a fixing means 30 along a fixing inlet guide 44 after being discharged by a discharging means (not shown), and heated and pressurized by the fixing means 30 to be fixed. The paper is discharged by a paper discharge roller 32 to a paper discharge tray (not shown).

Hereinafter, the configuration of the present embodiment will be further described in detail. The transfer conveyance belt 18 is stretched over and stretched between the belt cleaning facing roller 13, the driven roller 14, the driven roller 15, and the driven roller 16. Each transfer bias roller 23 is brought into contact with the back surface of the transfer conveyance belt 18 by a roller pressing means 29 composed of a compression spring or the like, and the surface of the transfer conveyance belt 18 is in contact with the photoreceptor 1 via the transfer conveyance belt 18. -It is biased in the direction of pressing.
The belt cleaning facing roller 13 also serves as a driving roller for the transfer conveyance belt 18 and is connected to a driving motor (not shown) via a driving force transmission means such as a gear train. The transfer / conveying belt 18 is adjusted and set so as to run and drive at a process speed of 150 mm / sec by the drive motor (not shown).
The rollers 13, 14, 15, 16, and 23 are rotatably supported and supported from both sides of the transfer conveyance belt 18 by transfer transfer belt unit side plates (not shown).

  The transfer bias roller 23 is disposed at a contact portion between the transfer member belt 18 facing the photosensitive member 1 disposed for each image forming unit, and a power source and transfer current application (not shown) are applied to the transfer bias roller 23. A predetermined transfer bias is applied via the means 103.

The transfer conveyance belt 18 is made of the same material as that of the intermediate transfer belt 10 of the first embodiment, that is, PVDF (polyvinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PAI (polyamide). (Imide), a resin such as PC (polycarbonate) or the like is formed in a single layer or a plurality of layers, a conductive material such as carbon black is dispersed, the volume resistivity is 10 ⁸ to 10 ¹² Ωcm, and the surface resistivity is 10 It is adjusted and set to be in the range of ⁹ to 10 ¹³ Ω / □. Note that a release layer may be coated on the surface of the transfer / conveyance belt 18 as necessary, and the manufacturing method of the transfer / conveyance belt 18 is the same as that of the intermediate transfer belt 10 of the first embodiment.

  In the vicinity of the transfer conveyance belt 18 facing the belt cleaning roller 13, a belt cleaning unit 19 having the same configuration as that of the first embodiment and the like for cleaning the transfer conveyance belt 18 is disposed. It is configured to press against the surface of 18 and stop the toner, paper dust, etc., and clean it.

  In order to facilitate the cleaning of the transfer / conveying belt 18, a solid lubricant 155 formed of a raw material containing a fatty acid metal salt (A) and an inorganic lubricant (B) having the same configuration as in the first embodiment is applied with a lubricant. A step of applying or adhering to the transfer / conveying belt 18 by the member 152 is performed. Also in this embodiment, a polymerized toner generated by the same polymerization method as in the first embodiment is used.

  In the image forming apparatus according to the second embodiment, as in the first embodiment, a toner image correction pattern is formed on the transfer conveyance belt 18, and each toner image detection sensor 46 detects the toner image. That is, in the image forming apparatus of the second embodiment, as in the first embodiment, in order to form a predetermined resist pattern on the four image forming units that perform image formation with yellow toner, magenta toner, cyan toner, and black toner, respectively. A resist pattern generating means for generating a resist pattern on the exposure means; and an optical sensor unit 45 as a pattern detecting means for detecting the resist pattern formed on each of the image forming means and transferred onto the transfer conveyance belt 18; Further, a misalignment correcting means for correcting misalignment based on the result detected by the optical sensor unit 45 is provided. Among these, various known configurations can be adopted as the resist pattern generating means and the positional deviation correcting means.

Also in the present exemplary embodiment, in a manner substantially similar to that illustrated in FIG. 2, a sensor facing member 49 is disposed at a position facing the toner image detection sensor 46 of the optical sensor unit 45 with the transfer conveyance belt 18 instead of the intermediate transfer belt 10 interposed therebetween. Is disposed, and a sensor facing member contacting / separating mechanism 50 is disposed as a facing means contacting / separating means for allowing the sensor facing member 49 and the back surface of the transfer conveyance belt 18 to contact and separate from each other. The configuration and operation including the control of the sensor facing member contact / separation mechanism 50 in the present embodiment can be performed by those skilled in the art by replacing the “intermediate transfer belt 10” described in the first embodiment with the “transfer conveying belt 18”. Since it can be easily understood and implemented, further explanation is omitted.
However, in this embodiment, the transfer bias roller 23 serving as a transfer unit is provided for each image forming unit as compared with the arrangement positions of the sensor facing member 49, the optical sensor unit 45, and the sensor facing member contact / separation mechanism 50 in the first embodiment. Therefore, the transfer bias belts 23 are different from the transfer bias rollers 23 in that they are arranged on the most downstream side in the arrow moving direction in the drawing.

  In the second embodiment, when the configuration almost the same as that shown in FIGS. 2 and 3 is adopted, it is needless to say that the above-described effects according to claims 1, 3, and 8 corresponding thereto are obtained.

  Further, the image forming apparatus according to the second embodiment can employ substantially the same configuration as that of the first modification shown in Fig. 6 (hereinafter referred to as "the third modification" for convenience). The configuration and operation including the control in the case where the third modification having the same configuration as that of the first modification shown in FIG. 6 is adopted is the same as the “intermediate transfer belt 10” described in the first modification. If it is read as “belt 18”, those skilled in the art can easily understand and implement it, so further explanation will be omitted. When the third modification is adopted in the second embodiment, it is needless to say that the above-described effects according to claims 2 and 8 corresponding thereto are obtained.

(Embodiment 3)
A sixth embodiment of the present invention will be described with reference to FIG. The image forming apparatus shown in FIG. 9 is also based on the same technical idea as that of the first embodiment, the first and second modifications, the second embodiment, and the like described above. Constituent elements that exhibit the same function will be briefly described with the same reference numerals as those used in the above embodiments and the like unless there is a possibility of confusion. FIG. 2 is a schematic configuration diagram showing a color image forming apparatus according to the third embodiment. In the present embodiment, an example using an endless photoreceptor belt 1 as an image carrier will be described.
In the color image forming apparatus shown in FIG. 9, four image forming units (or image forming units) that perform image formation with yellow toner, magenta toner, cyan toner, and black toner in this order from left to right in FIG. 1 is a tandem color image forming apparatus arranged side by side below a body belt 1.

  As shown in FIG. 9, the image forming apparatus in the present embodiment has a photoreceptor belt 1 composed of an endless belt, and a photoreceptor as a cleaning unit provided with a cleaning blade 3 around the photoreceptor belt 1. A cleaning unit 2, chargers 4a, 4b, 4c and 4d as charging means, exposure means 5, developing means (yellow developing device 6, magenta developing device 7, cyan developing device 8, black developing device 9) and the like are arranged. Yes.

  When forming a full-color image, the surface of the photoreceptor belt 1 is uniformly charged by the chargers 4a, 4b, 4c, and 4d. Next, exposure light such as a laser is irradiated by the exposure means 5 based on the image information, and an electrostatic latent image is formed on the surface of the uniformly charged photoreceptor belt 1. The electrostatic latent image formed on the photosensitive belt 1 can be developed by sequentially supplying toner of each color by a yellow developing unit 6, a magenta developing unit 7, a cyan developing unit 8, and a black developing unit 9 in order. A visual image (toner image) is formed, and in the toner image transfer unit in each image forming unit, a primary transfer bias is used as a primary transfer unit via a power supply unit (not shown) and a primary transfer current applying unit 201. By being applied to the non-contact type primary transfer electrode 24, the visible images of the respective colors are sequentially transferred onto the photosensitive belt 1 running in the direction of the arrow in FIG. Is formed.

The transfer paper 25 is separated one by one by a paper feed roller 26 of the sheet feeding device 31 and a separating means (not shown) and fed via a transfer paper transport roller 27. After the leading edge is temporarily stopped and the oblique shift is corrected, the leading edge of the four-color superimposed image on the photosensitive belt 1 is fed from the registration roller 28 at the timing when the leading edge reaches the secondary transfer position. A four-color superimposed image on the photoreceptor belt 1 is a secondary transfer roller as a secondary transfer unit to which a predetermined voltage is applied via a secondary transfer position, that is, a power source (not shown) and a secondary transfer current applying unit 202. 21 is collectively transferred to the transfer paper 25.
The four-color superimposed image transferred to the transfer paper 25 is discharged to a fixing means 30 along a fixing inlet guide 44 after being discharged by a discharging means (not shown), and heated and pressurized by the fixing means 30 to be fixed. The paper is discharged by a paper discharge roller 32 to a paper discharge tray (not shown).

Hereinafter, the configuration of the present embodiment will be further described in detail. The photosensitive belt 1 is stretched over and stretched around a secondary transfer counter roller 12, a belt cleaning counter roller 13, a driven roller 14, and a driven roller 15.
The secondary transfer counter roller 12 also serves as a driving roller for the photosensitive belt 1 and is connected to a driving motor (not shown) that drives the photosensitive belt 1 via a driving force transmission unit such as a gear train. The photosensitive belt 1 is adjusted and set by the drive motor (not shown) so that the process speed is 150 mm / sec.
The rollers 12, 13, 14, and 15 are rotatably supported and supported from both sides of the photosensitive belt 1 by a photosensitive belt unit side plate (not shown).

Each primary transfer electrode 24 is a photosensitive belt facing the yellow developing unit 6, the magenta developing unit 7, the cyan developing unit 8, and the black developing unit 9 disposed for each image forming unit with the photosensitive belt 1 interposed therebetween. 1 is arranged in a non-contact manner on the back side. A predetermined transfer bias is applied to the primary transfer electrode 24 via a power source (not shown) and a primary transfer current applying unit 201.
The photosensitive belt 1 is formed by providing a conductive layer on the surface of PET (polyethylene terephthalate) or the like and applying a photosensitive agent thereon.

  In the vicinity of the photoreceptor belt 1 facing the belt cleaning roller 13, a photoreceptor cleaning unit 3 having the same configuration as that of the first embodiment and the like for cleaning the photoreceptor belt 1 is disposed. The photosensitive member cleaning unit 3 is provided with a cleaning blade 3 made of urethane rubber. The cleaning blade 3 is configured to press the tip of the cleaning blade 3 against the surface of the photosensitive belt 1 to dam the toner and clean it. .

  In order to facilitate cleaning of the photoreceptor belt 1, a lubricant is applied to the solid lubricant 155 made of a raw material containing the fatty acid metal salt (A) and the inorganic lubricant (B) having the same configuration as in the first embodiment. A step of applying or adhering to the photosensitive belt 1 by the member 152 is performed. Also in this embodiment, a polymerized toner generated by the same polymerization method as in the first embodiment is used.

  In the image forming apparatus according to the third embodiment, as in the first embodiment, a toner image correction pattern is formed on the photosensitive belt 1, and each toner image detection sensor 46 detects the toner image. That is, in the image forming apparatus of the third embodiment, as in the first embodiment, in order to form a predetermined resist pattern on four image forming units that perform image formation with yellow toner, magenta toner, cyan toner, and black toner, respectively. A resist pattern generating means for generating a resist pattern on the exposure means; and an optical sensor unit 45 as a pattern detecting means for detecting the resist pattern formed on each of the image forming means and transferred onto the photosensitive belt 1; Further, a misalignment correcting means for correcting misalignment based on the result detected by the optical sensor unit 45 is provided. Among these, various known configurations can be adopted as the resist pattern generating means and the positional deviation correcting means.

  Also in this embodiment, as shown in FIG. 2, the sensor facing member 49 is located at a position facing the toner image detection sensor 46 of the optical sensor unit 45 with the photosensitive belt 1 instead of the intermediate transfer belt 10 interposed therebetween. A sensor facing member contacting / separating mechanism 50 is disposed as a facing means contacting / separating means that allows the sensor facing member 49 and the back surface of the photosensitive belt 1 to contact and separate from each other. The configuration and operation including the control of the sensor facing member contact / separation mechanism 50 in the present embodiment can be performed by those skilled in the art by replacing the “intermediate transfer belt 10” described in the first embodiment with the “photosensitive belt 1”. Since it can be easily understood and implemented, further explanation is omitted.

  When the configuration shown in FIG. 2 and FIG. 3 is adopted in the third embodiment, it is needless to say that the above-described effects according to claims 1, 3 to 5, and 9 corresponding thereto are obtained.

  Also, the image forming apparatus according to the third embodiment can employ substantially the same configuration as that of the modified example 1 shown in FIG. 6 (hereinafter, this is referred to as “modified example 4” for convenience). In the present embodiment, the configuration and operation including the control in the case where the modification 4 substantially the same as the modification 1 shown in FIG. 6 is adopted is the same as the modification 4 in the “intermediate transfer belt 10” described in the modification 1. In this case, the term “photoreceptor belt 1” can be easily understood and practiced by those skilled in the art, so that further explanation is omitted. When the modification 4 is adopted in the third embodiment, it is needless to say that the above-described effects according to claims 2 and 9 corresponding thereto are obtained.

  Also, the image forming apparatus according to the third embodiment can employ substantially the same configuration as that of the second modification shown in FIG. 7 (hereinafter, this will be referred to as “modification 5” for convenience). In the present embodiment, the configuration and operation including the control in the case where the fifth modification similar to that shown in FIG. 7 is adopted is the same as that of the “intermediate transfer belt 10” described in the second modification. If it is read as “belt 1”, those skilled in the art can easily understand and implement it, so further explanation will be omitted. When the fifth modification is adopted in the third embodiment, it is needless to say that the above-described effects according to claims 6 and 9 corresponding thereto are obtained.

  As described above, the present invention has been described with respect to specific embodiments, modifications, and the like. However, the technical scope disclosed by the present invention is limited to those exemplified in the above-described embodiments, modifications, or examples. However, it should be understood that various embodiments, modifications, or examples may be configured within the scope of the present invention in accordance with the necessity and application thereof. It will be clear to the trader.

For example, in the first to third embodiments, the toner image detection sensor 46 as the toner image detection means includes all known detection sensors equivalent to this, and the number of the arrangement is at least 1 if the number of the arrangement sensors can perform the function. I just need it. Similarly, the opposing member 49 as the opposing means includes all known members equivalent to this, and the number of the arranged members may be at least one as long as the function can be exhibited.
Similarly, the sensor facing member contacting / separating mechanism 50 as the facing means contacting / separating means is not limited to this, and instead of the drive motor 51 as the drive source constituting the sensor facing member contacting / separating mechanism 50, for example, a solenoid is adopted. It may be combined with a spring, and may be any as long as it exhibits a function as an opposing means contacting / separating means. The driving force transmission mechanism 56 shown in FIG. 6 having the function as the driving force transmission means of the facing means contacting / separating means and the driving force transmission mechanism 76 shown in FIG. 7 are merely examples, and other driving force transmission means equivalent to these. But it ’s okay.

1 Photoreceptor belt (image carrier)
2, 2a to 2d Photoconductor cleaning unit (cleaning means)
4a to 4d charger (charging means)
5a to 5d Exposure means 6 Yellow developing device (developing means)
7 Magenta developer (Development means)
8 Cyan developer (developing means)
9 Black developer (Development means)
10 Intermediate transfer belt (image carrier, intermediate transfer member)
11a to 11d Primary transfer bias roller (primary transfer means)
18 Transfer conveyor belt (image carrier, transfer conveyor)
19 Belt cleaning unit 21 Secondary transfer roller (transfer means, secondary transfer means)
23 Transfer bias roller (transfer means)
24a to 24d Primary transfer electrode (primary transfer means)
25 Transfer paper, transfer material (sheet-shaped recording medium)
30 Fixing means 45 Optical sensor unit 46 Toner image detection sensor (toner image detection means)
48 Sensor facing shaft 49 Sensor facing member (facing means, facing member)
49a Sensor facing contact portion 49b Non-contact portion 50 Sensor facing member contacting / separating mechanism (facing device contacting / separating device)
51 Drive motor (drive source for facing / contacting means)
53 Cleaning unit 54 Cleaning member (cleaning means)
54a Cleaning brush (composing cleaning means)
56 Driving force transmission mechanism (Driving force transmission means of opposing means contacting / separating means)
57 Drive motor (drive source for cleaning means)
70 Transfer roller contact / separation mechanism (transfer device contact / separation device)
71 Drive motor (drive source for transfer means contacting / separating means)
76 Driving force transmission mechanism (driving force transmission means of facing means contacting / separating means)

JP 2007-148197 A

Claims (9)

An endless belt-shaped image carrier that carries a toner image, transfer means for transferring the toner image on the image carrier to a sheet-like recording medium, and disposed on the image carrier that faces the image carrier And at least one toner image detecting means for detecting a toner image, and at least one facing means arranged so as to face the toner image detecting means with the image carrier sandwiched therebetween and to be in contact with the image carrier. In the image forming apparatus,
An image forming apparatus, comprising: an opposing means contacting / separating means for allowing the opposing means and the image carrier to contact and separate. The image forming apparatus according to claim 1.
Cleaning means for cleaning the toner image detection means;
The image forming apparatus according to claim 1, wherein a driving source for driving the facing unit contacting / separating unit is the same as a driving source for driving the cleaning unit. The image forming apparatus according to claim 1 or 2,
The image forming apparatus according to claim 1, wherein the facing unit contacts the image carrier only when the toner image is detected by the toner image detecting unit. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus according to claim 1, wherein the facing unit is disposed only at a position facing the toner image detecting unit through the image carrier. The image forming apparatus according to any one of claims 1 to 4,
The image forming apparatus according to claim 1, wherein the toner image detecting unit and the facing unit are arranged upstream of the transfer unit in the moving direction of the image carrier. The image forming apparatus according to claim 1,
A transfer means contacting / separating means for allowing the transfer means and the image carrier to contact and separate;
An image forming apparatus according to claim 1, wherein a driving source for driving the facing unit contacting / separating unit is the same as a driving source for driving the transfer unit contacting / separating unit. The image forming apparatus according to any one of claims 1 to 6,
The image forming apparatus, wherein the image carrier is an intermediate transfer member. The image forming apparatus according to any one of claims 1 to 4,
The image forming apparatus, wherein the image carrier is a transfer carrier. The image forming apparatus according to any one of claims 1 to 6,
The image forming apparatus, wherein the image carrier is a photosensitive belt.

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