JP5653064B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a toner image detecting device for detecting a toner image formed on an image carrier, and for example, an image forming apparatus such as a copying machine and a laser beam printer using an electrophotographic method or an electrostatic recording method. The present invention relates to a toner image detection device applied to the above.

  In an image forming apparatus using an electrophotographic system, a toner is attached to an electrostatic latent image formed on an image carrier such as a photosensitive drum to make a visible image. A configuration is used in which a detection member for detecting the toner image formed on the image carrier is provided, and the conditions for forming the toner image are adjusted based on the detection result. As a specific example of the detection member, a light receiving level is photoelectrically converted using an optical sensor composed of a pair of light projecting and receiving parts (light emitting part and reflected light incident part). In such a configuration, it is necessary to keep the received light detection level constant by protecting the toner from adhering to the light emitting surface and the light incident surface of the optical sensor. For this purpose, a shutter mechanism that opens and closes the sensor surface is used.

  As a shutter mechanism, there is a configuration as in Patent Document 1 in which the moving direction of the shutter is the direction in which the light emitting part and the light incident part are arranged, that is, the longitudinal direction of the sensor. Moreover, the structure which exposes and shields a sensor surface by rotating a disk-shaped shutter centering on the axis orthogonal to a sensor surface and a center like patent document 2 is mentioned.

  In the configuration in which the shutter is rotated as in Patent Document 2, the drive mechanism for the shutter is complicated, and therefore a configuration in which the shutter is moved in one direction is preferable in order to easily open and close the shutter.

JP-A-2005-275117 JP 2006-276249 A

  The arrangement relationship between the light emitting part and the light incident part of the sensor will be described. If the light emitting part and the light incident part of the sensor are arranged along the moving direction of the image carrier, it is necessary to increase the length of the toner image in the moving direction in order to increase detection accuracy. As a result, the toner consumption increases. Therefore, it is desirable that the light emitting part and the light incident part of the sensor be arranged in a direction orthogonal to the moving direction.

  In such a configuration, due to space limitations, the shutter drive source is provided on the end side of the image carrier in the direction orthogonal to the moving direction of the image carrier. As a result, as described in Patent Document 1, the configuration in which the moving direction of the shutter is moved in a direction orthogonal to the moving direction of the image carrier is simplified.

  However, when the light emitting unit and the light incident unit are arranged in a line, that is, in a direction orthogonal to the moving direction of the image carrier, the amount of movement of the shutter increases. As a result, the time required for opening and closing the shutter increases.

Accordingly, the present invention provides a movable image carrier, toner image forming means for forming a toner image on the image carrier, and light emission arranged in a width direction perpendicular to the moving direction of the image carrier. has a detection unit consisting of parts and light incident portion, and irradiates the light emitted from the light emitting portion to the toner image formed on the image bearing member, a light incident on the light entrance portion from the toner image An image forming apparatus comprising: a detection member that detects; and an adjustment unit that adjusts a condition of the toner image forming unit based on a detection result detected by the detection member , and has an opening that can open and close the detection unit. And a film-like shutter arranged to be movable so as to surround the detection portion in a state of being bent into a U shape that forms a convex portion toward the image carrier, and the image carrier in the width direction. Arranged on the end side of the Yes a driving unit providing a driving force for opening and closing operation of Potter, a drive transmitting part which driving force from the driving unit is transmitted, and a driven transmission unit for moving the shutter in accordance with the movement of the drive transmission unit and a conversion mechanism for converting the movement to the width direction of the driving force transmitting portion, wherein the movement of a closer or away from the direction on the image bearing member of the drive transmission portion in the direction orthogonal to the width direction, It is characterized by having.

  According to the present invention, the light emitting portion and the light incident portion of the detection member are arranged side by side in a direction orthogonal to the moving direction of the image carrier, and the drive source is arranged on the end side of the image carrier. Even in such a case, the shutter can be opened and closed with a small amount of movement of the drive source.

The typical perspective view explaining the composition of the example of the present invention. Typical sectional drawing explaining the structure of the Example of this invention FIG. 1 is a schematic perspective view illustrating a shutter configuration according to an embodiment of the present invention. FIG. 2 is a schematic perspective view illustrating a shutter configuration according to an embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a shutter configuration according to an embodiment of the present invention. FIG. 4 is a schematic perspective view illustrating a shutter configuration according to an embodiment of the present invention. The typical perspective view explaining the shutter film of the Example of this invention Typical sectional drawing explaining the shutter film of the Example of this invention Schematic perspective view of a concentration sensor used in an embodiment of the present invention Schematic perspective view of a shutter drive source used in an embodiment of the present invention 1 is a schematic cross-sectional view of a main part of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic perspective view of a process unit excluding a developing device according to an embodiment of the present invention.

〔Example〕
Hereinafter, embodiments of the present invention will be described. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

  An image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a schematic cross-sectional view of an image forming unit according to an embodiment of the present invention, and FIG. 12 is a schematic perspective view of a photosensitive drum and a density sensor.

  As shown in FIG. 11, the full-color image forming apparatus has an image forming unit that forms an image using each toner of yellow Y, magenta M, cyan C, and black Bk. In this embodiment, the image forming units Y, M, C, and Bk have the same configuration except for the toner color.

  The operation of the entire image forming apparatus will be described with reference to FIG.

  First, as an explanation of the image forming unit, the image forming unit PY will be described as a representative. The photosensitive drum 110Y, which is an image carrier, is rotatably provided.

  The primary charger 21Y uniformly charges the surface of the rotating photosensitive drum 110Y. Thereafter, the uniformly charged surface is exposed by an exposure device 22Y such as a laser in accordance with an information signal, thereby forming an electrostatic latent image on the photosensitive drum 110Y. The formed electrostatic latent image is visualized as a toner image on the photosensitive drum 110Y by the developing device 101Y. In this embodiment, a two-component development method using toner and carrier is adopted. In this embodiment, the electrostatic latent image forming unit and the developing device are toner image forming means.

  Next, the visible image is transferred to the intermediate transfer belt 24 by the primary transfer charger 23Y.

  Such a process is performed in each image forming unit, and a color image is formed on the intermediate transfer belt 24.

  The toner image formed on the intermediate transfer belt 24 is conveyed to the secondary transfer unit 29 and is secondarily transferred to the recording material 27 conveyed on the paper conveyance path 28 in the secondary transfer unit 29. The recording material 27 on which the toner image is formed is further fixed on the recording material by heat and pressure by the fixing device 25.

  On the other hand, the untransferred toner on each photosensitive drum 110 is removed by each cleaning device 26. On the other hand, toner used in the developing device 101 is supplied from the toner supply tank 20.

  In this embodiment, a detection toner image formed on the photosensitive drum 110 under a preset condition is formed, and the detection toner image is detected by the density sensor 10 as a sensor unit. In this embodiment, a toner density patch is formed as a detection toner image. The toner density patch formed on the photosensitive drum 110 is obtained by developing a preset electrostatic latent image with a developing device.

  And it has an adjustment part (CPU) which adjusts image formation conditions, such as development conditions or electrostatic latent image formation conditions, so that a density may become predetermined density based on a detection result of density sensor 10. In this embodiment, as a method for adjusting the density, it is assumed that the toner is mixed with the carrier.

  The density sensor 10 is disposed downstream of the developing unit in the rotation direction of the photosensitive drum 110 and upstream of the primary transfer unit. The arrangement in the photosensitive drum bus direction (rotation axis direction) is provided at a substantially central portion.

  The density sensor 10 according to the present exemplary embodiment includes a light emitting unit that emits light toward the detection toner image and a light incident unit that receives reflected light that is reflected by irradiating the toner image with light. . The light emitting part and the light incident part are arranged side by side in the photosensitive drum bus direction. As a result, the configuration of the detection surface of the density sensor 10 is configured such that the length in the photosensitive drum bus direction is longer than the length in the direction orthogonal to the photosensitive drum bus direction.

  As shown in FIG. 12, the arrangement of the toner density sensor in this embodiment is arranged so that the photosensitive drum bus line direction (rotation axis direction) and the sensor longitudinal direction are parallel, and highly accurate toner density detection can be performed in a shorter time. Realized.

  Next, the shutter configuration including the density sensor will be described.

  FIG. 1 is a schematic view of a sensor unit 10 according to the first embodiment of the present invention, and FIG. 2 shows a schematic cross section of the sensor unit 10.

  The sensor unit 10 is accommodated in a closed space by the casings 5 and 6 and the shutter 2 in order to protect the density sensor 7 as a detection member from scattered toner. The shutter mechanism 1 has a shutter mechanism 1 that can be opened and closed so that the shutter 2 is opened to expose the sensor surface when in use, and the shutter 2 is closed to protect the sensor surface from scattered toner when not in use.

  Next, the operation of the shutter mechanism 1 will be described in detail with reference to FIGS.

First, 7a is a light emitting portion for emitting light (light emitting portion) in FIG. 3, 7b includes a light receiving unit which light reflected by the toner image is incident (light entrance portion) der is, the light emitting portion and the light incident and the Department shall be the detection portion of the sensor 7.

  The shutter lever 4 as a drive transmission unit for transmitting a driving force to the shutter is driven in the longitudinal direction A of the sensor 7 by the power from the shutter drive source as a driving unit for providing a driving force for the opening / closing operation of the shutter. . In this embodiment, a solenoid is used as the shutter drive source. As shown in FIG. 10, the solenoid is provided at a position away from the shutter. In this embodiment, the solenoid is arranged in a space on the end side of the photosensitive drum in the direction of the rotation axis of the photosensitive drum 110, that is, a space outside the end portion of the photosensitive drum 110.

The shutter mechanism 1 has a conversion mechanism that converts the movement of the shutter lever 4 in the direction of the rotation axis of the photosensitive drum 110 (the width orthogonal to the moving direction of the photosensitive drum 110) into the movement of the shutter in the direction orthogonal to the width direction. . As a component , the movement of the shutter lever 4 (in the width direction) is a direction in which the shutter lever 4 approaches or moves away from the photosensitive drum (image carrier ) and is perpendicular to the movement direction (width direction) of the shutter lever 4. A shutter slider 3 serving as a driven transmission portion for conversion into The shutter slider 3 converts the operation direction of the shutter lever 4 by 90 degrees by a cam mechanism, and is a direction that approaches or moves away from the photosensitive drum by the same amount as the movement amount of the shutter lever 4 and the movement direction (width direction) of the shutter lever 4. Slide in the orthogonal direction B ( FIGS. 2 and 4).

The mechanism will be described in detail with reference to FIG. The shutter lever 4 is provided with a cylindrical protrusion 11, and the shutter slider 3 is provided with a groove 12. The protrusion 11 moves in the groove. Referring to FIG. 4, when the shutter lever 4 moves, the protrusion 11 moves, and the protrusion 11 and the side surface of the groove abut against each other to press the shutter slider 3 in the direction B. This is a mechanism that moves in a direction that approaches or moves away from the photosensitive drum and that is perpendicular to the width direction . That is, one is a groove portion that is an inclined portion, and the other is a configuration of a protruding portion as a contact portion that contacts the inclined portion. In the present embodiment, the protrusion 11 is provided on the shutter lever 4 and the groove is provided on the shutter slider 3, and this relationship may be reversed. Of course, the structure which changes the movement of a shutter lever to the movement of the direction B by another structure may be sufficient. Specifically, the shutter slider has an inclined portion with an inclined contact surface, and the shutter lever 4 has another inclined portion that contacts the contact surface of the shutter slider-3 by movement. It ’s okay.

  In the cam mechanism, the cam angle (inclination angle) is set to 45 ° in order to minimize the twisting force when changing the operation direction. By setting this angle, the driving amount of the shutter lever 4 and the shutter slider are set. 3 is 1: 1 (FIG. 5).

The shutter 2 is formed of a film to reduce the operating mass, and is attached to the shutter slider 3 (FIG. 6) and slides with the shutter slider 3 to open the surface of the sensor 7 (detection unit) (FIG. 3). In this embodiment, the shutter has an opening. The film-like shutter 2 is movably disposed so as to surround the detection portion of the sensor 7 in a state of being bent in a U shape that forms a convex portion toward the photosensitive drum 111 (image carrier) (FIG. 2). By sliding the inner surfaces of the casings 5 and 6 covering the sensor 7 in a circular arc shape, the overall configuration including the casings 5 and 6 can be reduced in size.

  In order to reduce the rubbing resistance of the shutter 2, it is preferable that the shutter sliding portion has a satin finish that is an uneven treatment, and it is desirable that the satin finish is on the surface of the shutter 2 instead of the casing configurations 5 and 6. This is because, when the satin finish is in the case, it is necessary to prevent the film tip from being caught by the uneven portion of the satin at the bent portion on the film movement locus. Therefore, bend the film to make it smoothly rush into the textured uneven part, or lengthen the film so that the film tip does not hit the bent part on the film movement trajectory. This is because it is necessary to prevent the film tip from being caught in the case satin portion. That is, the film is subjected to an unevenness process to smooth the casing, that is, the surface roughness (Ra) with which the film contacts is made larger than the roughness (Ra) with which the casing contacts. The contact area between the bodies can be reduced, and a smooth operation can be achieved.

  In addition, the shutter 2 reduces the light receiving level of the sensor light receiving unit when the shutter 2 is closed, and diffuses the light by irregularly reflecting the sensor light on the inner surface of the shutter film to minimize the arrival of the sensor light to the light receiving unit. In order to reduce the gloss of the surface, it is desirable to apply a texture.

  Next, the film operation when the shutter is closed will be described with reference to FIGS. Since the shutter 2 is a film, only the both ends of the opening slide with the housing at the shutter opening, so only the both ends of the opening receive contact pressure, and the center of the opening rises and the flatness is impaired. Occurs (FIG. 7). If the operation of closing the shutter 2 is performed in this state, the rear end of the opening of the shutter 2 may collide with the end of the casing when the shutter 2 is closed, and the shutter 2 may not be completely closed. In order to prevent the rear end of the opening of the shutter 2 from colliding with the end of the casing, the casing 5 is shaped to absorb the rising of the shutter film (FIG. 8, * mark). That is, when the shutter transitions from the open state to the closed state, an inclined portion is formed in the casing so that the distance between the shutter and the casing becomes narrower from the upstream side to the downstream side of the casing in the moving direction of the shutter. Provided.

FIG. 9 shows an optical density sensor. The density sensor has a light emitting portion 7a and a light receiving portion 7b, and has a rectangular shape. The arrangement of the sensor with respect to the photosensitive drum is as described above. Considering the shutter operation for a rectangular sensor, if the shutter operation is short rather than the longitudinal direction of the sensor 7 and the operation stroke is reduced, the shutter open time can be shortened and the protection function against scattered toner can be enhanced. . In addition, the size and weight can be reduced as compared with the case where the shutter is operated in the longitudinal direction. The specific shutter stroke is W = 15 mm and H = 5 mm for the size of the sensor 7, so the shutter stroke required to open the sensor 7 is: • Required shutter stroke in the sensor longitudinal direction = 15 mm or more The required shutter stroke in the sensor short direction = 5 mm or more. As described above, the shutter 2 according to the present embodiment realizes the short direction operation B by converting the shutter operation direction by 90 degrees with the cam mechanism with respect to the shutter drive source operation direction A in the longitudinal direction of the sensor 7. Yes.

  The drive transmission to the sensor unit 10 will be described with reference to FIG. Since the shutter operation has two positions, an open state and a closed state, and does not need to be controlled to an intermediate position in the operation range, a linear reciprocating operation such as a solenoid is more suitable as a drive source than a rotational drive by a motor.

  In this embodiment, as described above, the operation stroke of the sensor lever 4 of the sensor unit 10 is 5 mm, and the operation force is assumed to be 50 gf. Since both the operating force and stroke of the shutter are small, a small solenoid is used as the drive source to achieve miniaturization and cost reduction. As for the arrangement of the drive source, first, the solenoid 20 is arranged in an empty space of the process unit, the plunger of the solenoid 20 and the sensor lever 4 of the sensor unit 10 are connected by the wire member 9, and the solenoid stroke is changed to the wire member 9. Is transmitted 1: 1 to the operation of the sensor lever 4. By using a wire for the transmission member with the drive source, space saving and cost reduction of the power transmission unit are realized, and power transmission efficiency is improved.

  As described above, according to this embodiment, the size and weight of the shutter can be reduced, and the shutter operating mass and the shutter operating stroke can be reduced, and in combination with the downsizing of the drive source, the space and cost can be reduced.

  Further, since the shutter stroke can be reduced, the time required to open and close the shutter can be shortened, and as a result, the amount of toner attached to the sensor surface is reduced. In this embodiment, a solenoid is used as a drive source. However, the drive source is not limited to the configuration of this embodiment.

  In this embodiment, the sensor unit is a density sensor that detects the density of the toner image on the image carrier. However, the sensor unit is not limited to the density sensor, and the sensor detects the color misregistration amount of the image formed in each image forming unit. It is applicable to.

  In this embodiment, the toner image on the photosensitive drum is detected. However, by applying the configuration of the present invention to the sensor that detects the image formed on the intermediate transfer belt, the above-described configuration can be used. The same effect as the embodiment can be obtained.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the technical idea of the present invention.

100 Toner density sensor (assembly)
DESCRIPTION OF SYMBOLS 101 Developing device 20 Toner supply tank 21 Primary charger 22 Issuing element 23 Transfer charger 24 Recording material transport belt 25 Fixing device 26 Transfer residual toner cleaning device 27 Recording material 1 Shutter mechanism 2 Shutter 3 Shutter slider 4 Shutter lever 5 Housing ( Up)
6 Case (bottom)
7 Toner density sensor (single unit)
8 Shutter spring 9 Drive transmission wire 20 Solenoid

Claims (5)

A movable image carrier;
Toner image forming means for forming a toner image on the image carrier;
Has a detection unit consisting of the image light emitting unit are disposed side by side in a width direction orthogonal to the moving direction of the carrier and the light entrance portion from the light emitting portion to the toner image formed on said image bearing member A detection member that irradiates the emitted light and detects light incident on the light incident portion from a toner image ;
An adjustment unit that adjusts a condition of the toner image forming unit based on a detection result detected by the detection member ;
An opening that can open and close the detection unit, and a film-like shape that is movably arranged so as to surround the detection unit in a state of being bent in a U shape that forms a convex portion toward the image carrier Shutter,
Wherein disposed on the end side of the image bearing member in the width direction, a driving unit providing a driving force for opening and closing operation of the shutter,
A drive transmission unit that transmits a driving force from the drive unit; and a driven transmission unit that moves the shutter along with the movement of the drive transmission unit, and the movement of the drive transmission unit in the width direction. A conversion mechanism that converts the driven transmission unit into movement in a direction that approaches or moves away from the image carrier and is orthogonal to the width direction ;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the driving unit is a solenoid. The inclined portion in at least one of the drive transmission portion and the driven transmission part is provided, the other is the contact portion is provided in contact with the inclined portion, said drive transmitting portion is moved in the width direction claim 1, wherein the contact portion is in pressing the inclined portion, and wherein the movement of Reruko the direction of the driving force transmitting portion is orthogonal to the width direction a closer or away from the direction to the image carrier Or the image forming apparatus according to 2;   The image forming apparatus according to claim 3, wherein an inclination angle of the inclined portion is 45 °. The said shutter moves while sliding on the inner surface of the housing | casing which accommodates the said detection member, The surface roughness of the said shutter is larger than the surface roughness of the inner surface of the said housing | casing. the image forming apparatus according to any one of 4.

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