Patent Grant
11402783
The present invention relates to an image forming apparatus using an electro-photographic system or an electrostatic recording system such as a copier, a printer, a facsimile machine and a multifunction machine having such plurality of functions and to a cartridge.
An image forming apparatus is configured to visualize an image by applying toner to an electrostatic latent image formed on an image bearing member such as a photosensitive drum. Hitherto, there has been known a configuration of providing a detection unit configured to detect a toner image formed on the image bearing member to adjust a condition for forming the toner image based on a detection result of the detection unit. Then, as such detection unit, there has been known a system having a light emitting portion and a light receiving portion configured to receive a reflection light of the light emitting portion and photoelectrically converting a level of the received light by using an optical sensor configured to detect the toner image without contact.
Still further, a detection unit in which a shutter mechanism for opening/closing an opening portion where a surface of a sensor is exposed and an optical sensor are unitized is known in order to protect the sensor surface of such optical sensor to keep a photosensitive level constant as disclosed in Japanese Patent Application Laid-open No. 2015-143804 for example. This detection unit reduces an opening/closing stroke of the shutter by setting an opening/closing direction of the shutter in a direction orthogonal to a predetermined direction which is a drive input direction. This arrangement permits to save space, to shorten an operation time required for opening/closing the shutter and to prevent scattering toner from adhering on the surface of the sensor.
However, the detection unit disclosed in Japanese Patent Application Laid-open No. 2015-143804 has had such a problem that foreign substances such as carriers may infiltrate into a casing of the detection unit from the shutter when the shutter is opened and may infiltrate into a sliding portion in an opening/closing mechanism of the shutter. In a case where a developing unit is located above the detection unit in particular, the foreign substances fallen from the developing unit tend to infiltrate inside of the casing of the detection unit from the opened shutter. If such shutter opening/closing operations are repeated in this state, the foreign substances caught in the sliding portion of the opening/closing mechanism of the shutter get stuck on a resin surface of the sliding portion. Then, there is a possibility of inducing an increase of a sliding resistance by scratching a resin surface of a counterpart component by sliding while catching the foreign substances. As a result, an opening/closing failure of the shutter may occur in a short period of time which is significantly shorter than a life assumed from wear caused by friction, possibly increasing a downtime of the image forming apparatus and a replacement load of a service person.
Accordingly, the present disclosure aims at providing an image forming apparatus and a cartridge provided with a detection unit capable of suppressing wear of an opening/closing mechanism of a shutter. That is, the present disclosure aims at providing an image forming apparatus capable of suppressing the wear of the opening/closing mechanism of the shutter.
According to a first aspect of the present invention, an image forming apparatus includes a rotatable image bearing member, an image forming unit configured to form an image on the image bearing member, a detection unit configured to detect a toner image formed on the image bearing member, and a control portion configured to control the image forming unit based on a detection result of the detection unit. The detection unit comprises a casing having an opening portion, an optical sensor disposed within the casing facing the image bearing member to detect the toner image and comprising a light emitting portion configured to emit light to the image bearing member through the opening portion and a light receiving portion configured to receive the light reflected from the image bearing member, a shutter portion comprising a shutter configured to open/close the opening portion, a moving member configured to reciprocally move along a predetermined direction, a groove portion provided on the moving member and extended in a direction intersecting with the predetermined direction, and a project portion provided on the shutter portion and engaging with the groove portion. The shutter is configured to open/close the opening portion as the project portion moves in a direction intersecting with the predetermined direction as the moving member moves in the predetermined direction. The groove portion is disposed perpendicularly above an extension line of an optical axis of the light irradiated from the light emitting portion to the image bearing member.
According to a second aspect of the present invention, an image forming apparatus includes a rotatable image bearing member, an image forming unit configured to form an image on the image bearing member, a detection unit configured to detect a toner image formed on the image bearing member, and a control portion configured to control the image forming unit based on a detection result of the detection unit. The detection unit comprises a casing having an opening portion, an optical sensor disposed within the casing facing the image bearing member to detect the toner image and comprising a light emitting portion configured to emit light to the image bearing member through the opening portion and a light receiving portion configured to receive the light reflected from the image bearing member, a shutter portion comprising a shutter configured to open/close the opening portion, a moving member configured to reciprocally move along a predetermined direction, a groove portion provided on the shutter portion and extended in a direction intersecting with the predetermined direction, and a project portion provided on the moving member and engaging with the groove portion. The shutter is configured to open/close the opening portion as the groove portion moves in a direction intersecting with the predetermined direction as the moving member moves in the predetermined direction. The groove portion is disposed perpendicularly above an extension line of an optical axis of the light irradiated from the light emitting portion to the image bearing member.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An exemplary embodiment of the present disclosure will be described with reference to
Image Forming Apparatus
As illustrated in
A photosensitive drum 110 serving as an image bearing member is provided to be rotatable and a surface thereof is homogeneously charged by a primary charger 21. Then, an electrostatic latent image is formed on the surface of the homogeneously charged photosensitive drum 110 by exposing with light such as a laser beam modulated by an exposing unit 22 corresponding to information signals. The electrostatic latent image thus formed is visualized, i.e., developed, by a developing unit 200 as a toner image on the photosensitive drum 110. A two-component developing method of using toner and carrier is adopted in the present exemplary embodiment. The developing unit 200 includes a developing sleeve 201 which is one example of a developer bearing member that is capable of developing the electrostatic latent image on the photosensitive drum 110 as the toner image by developer.
In the present exemplary embodiment, the photosensitive drum 110, the primary charger 21, the developing unit 200 and a cleaning unit 26 are unitized as a process cartridge 9 that can be attached to the image forming apparatus 100. The process cartridge 9 is provided above the intermediate transfer belt 24 and is provided with a sensor unit 10 configured to detect the toner image formed on the photosensitive drum 110 as described later.
Next, the visualized image, i.e., the toner image, is transferred by a primary transfer roller 23 onto the intermediate transfer belt 24. At this time, the toner images of the respective colors are sequentially superimposed from the respective image forming units PY, PM, PC and PK onto the intermediate transfer belt 24 and are conveyed to a secondary transfer portion 29. Then, the toner images are secondarily transferred onto a sheet material, i.e., recording material, 27 such as a sheet of paper or an OHP sheet that has been conveyed along a recording material conveyance path 28 at the secondary transfer portion 29. The recording material 27 onto which the toner images are laid is conveyed further to a fixing unit 25 to fix the image. Meanwhile, transfer residual toner left on the photosensitive drum 110 is removed by the cleaning unit 26. Toner is supplied from a toner replenishing tank 20 to replenish the toner consumed in the image forming operation. Note that carrier is also replenished together with the toner from the toner replenishing tank 20.
Sensor Unit
According to the present exemplary embodiment, the sensor unit 10 is disposed at a position facing the photosensitive drum 110 as one example of the detection unit as illustrated in
More specifically, as illustrated in
As illustrated in
The light emitting portion 7a and the light receiving portion 7b are arrayed in the rotation axial direction of the photosensitive drum 110. As a result, a length of a sensor detecting surface in the rotation axial direction of the photosensitive drum 110 composed of the light emitting portion 7a and the light receiving portion 7b of the concentration sensor 7 is longer than a length of the sensor detecting surface in a direction orthogonal to the rotation axial direction of the photosensitive drum 110. The concentration sensor 7 photo-electrically converts a level of the light received by the light receiving portion 7b and transmits it as a detection signal to the control portion 300. The control portion 300 controls variously based on this detection signal.
That is, as illustrated in
The sensor unit 10 constructed as described above includes the casing 5, the concentration sensor 7, a shutter 2 and a shutter mechanism 1 serving as an opening/closing mechanism for opening/closing the shutter 2 as illustrated in
The sensor unit 10 thus constructed stores the concentration sensor 7 in a closed space by the casing 5 and the shutter 2 to protect the concentration sensor 7 from scattered toner or the like when the sensor unit 10 is not in use. When the sensor unit 10 is used in detecting the patch image Pa for example, the shutter 2 is opened to expose the sensor detecting surface of the concentration sensor 7 out of the casing 5 through the opening portion 6 such that the sensor detecting surface faces the surface of the photosensitive drum 110. When the sensor unit 10 is not in use on the other hand, the shutter 2 is closed to protect the sensor detecting surface from the scattered toner and others.
Note that it is preferable to form the shutter 2 so as to have an emboss-finished internal surface to reduce glossiness of the surface of the film in order to lower the light-receiving level of the light receiving portion 7b when the shutter 2 is closed. This arrangement makes it possible to diffuse the light by irregularly reflecting the sensor light when the opening portion 6 is closed by the shutter 2 and to suppress the sensor light from reaching the light receiving portion 7b.
Here, the concentration sensor 7 of the present exemplary embodiment is disposed such that a sensor longitudinal direction is made parallel with the rotation axial direction of the photosensitive drum 110 (see
More specifically, according to the present exemplary embodiment, sizes of the concentration sensor 7 are set to be a width W=15 mm and a height H=5 mm. Due to that, the stroke of the shutter 2 to open the concentration sensor 7, i.e., a required shutter stroke=15 mm or more in a case where the shutter operation is made in the sensor longitudinal direction and a required shutter stroke=5 mm or more in a case where the shutter operation is made in the sensor lateral direction. In the present exemplary embodiment, a direction of the operation of the shutter 2 of the shutter mechanism 1 is set in the lateral direction of the concentration sensor 7, so that the shutter stroke is 5 mm.
Shutter Mechanism
To that end, the shutter mechanism 1 includes a shutter lever 4 serving as a moving member and a shutter slider 3 serving as a shutter member as illustrated in
The shutter lever 4 and the shutter slider 3 are arranged such that the shutter slider 3 is positioned gravitationally above the shutter lever 4 so as to relatively move by sliding with each other. The shutter slider 3 is disposed right under the casing element 51 located at an upper side of the casing 5 and relatively moves by sliding with each other. The shutter lever 4 is disposed on an upper surface of the casing element 52 located at a lower side of the casing 5 and relatively moves by sliding with each other. Accordingly, the shutter slider 3 is disposed between a part of the casing 5 and the shutter lever 4. Specifically, the shutter slider 3 is sandwiched between the casing element 51 and the shutter lever 4 and relatively moves while sliding with the respective members. Still further, the shutter lever 4 is disposed between a part of the casing 5 and the shutter slider 3. Specifically, the casing 5 is sandwiched between the casing element 52 and the shutter slider 3 and relative moves while sliding with the respective members.
In a case of the present exemplary embodiment, the shutter lever 4 moves reciprocally along a predetermined direction, i.e., the sensor longitudinal direction. Specifically, the shutter lever 4 moves reciprocally in the predetermined direction, i.e., in a direction D1 illustrated in
It is noted that because operational positions of the shutter 2 are two positions of the open state and the close state and it is not necessary to control the shutter 2 in an intermediate position of the movable range in a case of the present exemplary embodiment, that which makes linear reciprocal operations, such as the solenoid, is preferable as the driving source rather than that which makes a rotational drive such as a motor. Because an operational force and the operation stroke of the shutter 2 are both small, a small type solenoid is adopted as the driving source to achieve miniaturization and low cost.
The shutter slider 3 is reciprocally movable along a direction intersecting with the predetermined direction in a body with the shutter 2. In the present exemplary embodiment, the shutter slider 3 is reciprocally movable in a direction orthogonal to the predetermined direction, i.e., the moving direction of the shutter lever 4, and reciprocally moves in a direction D2 as illustrated in
Still further, according to the present exemplary embodiment, a return spring 8 composed of a compression coil spring is provided between the shutter lever 4 and a fixed part of the sensor unit 10 as illustrated in
Accordingly, in a case of the present exemplary embodiment, the shutter lever 4 is moved in a left direction in
Cam Mechanism
The cam mechanism provided in the shutter lever 4 and the shutter slider 3 will be described in detail with reference to
That is, the shutter slider 3 is provided with the cylindrical sliding boss 11 which is one example of an engaged portion, and the shutter lever 4 is provided with the groove portion 12 which is one example of an engaging portion. When the shutter lever 4 moves as illustrated in
While the shutter slider 3 moves while rubbing the shutter lever 4, the shutter slider 3 also moves while rubbing the casing 5. As illustrated in
According to the present exemplary embodiment, the groove portion 12 of the shutter lever 4 is formed straightly in a direction inclined by 45 degrees with respect to the predetermined direction and the groove portion 13 of the casing 5 is formed straightly in the direction orthogonal to the predetermined direction as illustrated in
In the case of the present exemplary embodiment, each of the sliding bosses 11 and 14 has a circular peripheral surface in section, i.e., a cylindrical outer peripheral surface in the present exemplary embodiment, and three in total of the sliding bosses are disposed on the shutter slider 3. Then, one sliding boss 11 is capable of entering one groove portion 12 and two sliding bosses 14 are capable of entering the groove portion 13. Therefore, the two sliding bosses 14 are arrayed in the direction orthogonal to the predetermined direction along the groove portion 13. As the shutter lever 4 moves, the groove portion 12 moves in the direction D1 and the sliding boss 11 moves along the groove portion 12 while sliding with the groove portion 12 as the side surfaces of the sliding boss 11 and the groove portion 12 abut and press with each other. At this time, because the sliding bosses 14 are guided while sliding with the groove portion 13 on the casing 5 side, the shutter slider 3 moves in the direction D2. Note that a reason why the two sliding bosses 14 are used to slide with the groove portion 13 on the casing 5 side is to cause the shutter slider 3 to move straightly along the groove portion 13 while suppressing the shutter slider 3 from turning during the operation.
Next, a gap between the sliding boss 11 and the groove portion 12 will be described with reference to
In the present exemplary embodiment, the gap is positively provided between a diameter of the sliding boss 11 of the shutter slider 3 and a width of the groove portion 12 of the shutter lever 4, i.e., a distance between the sliding surfaces 12a and 12b, such that a sliding load does not increase even if foreign substances infiltrate into the sliding portion 15 (see
Still further, a shape of a part of the sliding boss 11 where the sliding boss 11 collides against the foreign substance is preferable not to be flat but to be an inclined surface or a curved surface which can readily guide the foreign substance from an aspect of readiness of the sliding boss 11 in getting over the foreign substance adhering in a middle of the sliding surfaces 12a and 12b. Considering that the sliding boss 11 moves reciprocally, it is adequate to provide an inclined surface or a curved surface also on a counter face side. Then, it is preferable to form the sliding boss 11 into a cylindrical shape such that a contact part with the sliding surface of the sliding boss 11 does not become flat so that the foreign substance quickly exits out of the sliding surface.
An effect of decreasing the sliding resistance to a half is brought about by positively providing the gap in the sliding portion, not forming the sliding portion in a size by which the diameter of the sliding boss 11 fits with the width of the groove portion 12 without any gap. That is, the sliding resistance can be halved more than that in a case where the sliding boss 11 slides with both sliding surfaces by providing the gap because the sliding boss 11 slides with either one sliding surface and does not slide with the other sliding surface. This arrangement also provides an effect of reducing a rotational force generated in the shutter slider 3 at two reversing times of a top dead center and a bottom dead center by which the operation is reversed, in particular.
A cam angle, i.e., the inclination angle of the groove portion 12, is set at 45 degrees as described above in the cam mechanism composed of such sliding boss 11 and the groove portion 12 by considering a balance between the driving force and a shutter operation amount. Then, a ratio of a driving amount of the shutter lever 4 and a moving amount of the shutter slider 3 is set at one-to-one by setting at such angle. As the movement of the shutter slider 3 includes the two operational reversing portions as described above, it is preferable to set the cam angle at around 45 degrees in order to equalize the sliding loads of the shutter slider 3 at both portions.
As illustrated in
As illustrated in
Still further, it is preferable to implement a satin finish processing which is a roughening process on the sliding portion between the shutter 2 and the casing 5 to reduce a sliding resistance of the shutter 2. It is preferable to implement the satin finish processing not on the casing 5 but on the surface of the shutter 2 because the tip of the shutter 2 may be caught by the rugged part of the satin finish at a bent part on an operational locus of the shutter 2 if the casing 5 is satin-finished.
However, the casing 5 may be satin-finished. In such a case, the tip of the shutter 2 is bent such that the shutter 2 rushes smoothly to the satin-finished part to suppress such catching. Or, the shutter 2 is prolonged such that the tip of the shutter 2 is not caught by the bent part on the operational locus of the shutter 2 and such that the tip of the shutter 2 is not caught by the satin-finish part of the casing 5 in the circular arc operation of the shutter 2.
In any case, a contact area between the shutter 2 and the casing 5 can be reduced and a smooth operation can be achieved by satin-finishing either one sliding surface of the shutter 2 and casing 5 and by smoothing the other sliding surface. According to the present exemplary embodiment, the sliding surface of the shutter 2 is satin-finished such that roughness (Ra) of the sliding surface of the shutter 2 is larger than roughness of the sliding surface of the casing 5.
Sliding Portion
As illustrated in
Then, according to the present exemplary embodiment, the sliding portions 15 and 16 are disposed on an upper side of an extension line L1 of the optical axis of the light irradiated from the light emitting portion 7a (see
Still further, as illustrated in
If the holding portion 54 is formed at a position overlapping with the sliding portion 15 of the shutter lever 4 and the shutter slider 3 in the overlap direction D6, the holding portion 54 presses the sliding portion 15 in the overlap direction D6. In this case, if a pressing force of the sliding portion 15 is strong due to an allowance or the like and hampers the opening/closing operation of the shutter 2, the gap between the sliding boss 11 and the groove portion 12 and the operation thereof may not be adequately maintained.
Then, according to the present exemplary embodiment, the holding portions 54 are disposed in a region other than the sliding portion 15, i.e., in an outside area of the sliding portion 15, in a view from the overlap direction D6. This arrangement makes it possible to suppress the holding portions 54 from pressing the sliding portion 15 in the overlap direction D6 and from hampering the opening/closing operation of the shutter 2. An area S1 of the sliding portion 15 is set to be larger than an area S2 in which the regions of the shutter lever 4 overlapping with the holding portions 54 are totaled. Thereby, the sliding resistance generated by the movement regulation of the shutter lever 4 by the holding portions 54 becomes smaller than the sliding resistance generated by the shutter slider 3 sliding with the shutter lever 4. It is also possible to reduce a risk of catching foreign substances on a movement regulating surface by reducing the area S2 in contact with the shutter lever 4 and the holding portions 54. The holding portions 54 are also provided at two places across the sliding portion 15. This arrangement makes it possible to stably hold the shutter lever 4.
According to the image forming apparatus 100 of the present exemplary embodiment, the sliding portion 15 of the shutter lever 4 and the shutter slider 3 is disposed above the extension line L1 of the optical axis of the light irradiated from the light emitting portion 7a to the photosensitive drum 110 as described above. Therefore, the carriers which are relatively heavy metal particles infiltrated from the opening portion 6 tend to fall and accumulate in the space Sp where no sliding portions 15 and 16 exist. This arrangement makes it possible to remarkably reduce a possibility of causing sliding failure of the shutter slider 3, to suppress abrasion of the shutter mechanism 1 and to realize a stable and durably shutter opening/closing operation. That is, this arrangement makes it possible to reduce the infiltration of the foreign substances into the sliding portion 15 of the shutter mechanism 1 of the shutter 2 and to improve replacement intervals, to suppress a downtime and to reduce a service load of the sensor unit 10.
Still further, according to the image forming apparatus 100 of the present exemplary embodiment, the holding portions 54 hold so as to regulate the movement of the shutter lever 4 in the overlap direction D6 in the regions other than the sliding portion 15 of the shutter lever 4 and the shutter slider 3. Therefore, it is possible to suppress the holding portions 54 from pressing the sliding portion 15 in the overlap direction D6 and to arrange such that the holding portions 54 do not hamper the opening/closing operation of the shutter 2.
According to the image forming apparatus 100 of the present exemplary embodiment, the shutter stroke is reduced, so that the time required for opening/closing the shutter 2 is shortened. Due to that, it is possible to reduce a toner amount otherwise adhering on the sensor surface of the concentration sensor 7.
While the exemplary embodiment described above has been described about a case where the sliding portion 15 is disposed above the extension line L1 of the optical axis and where the holding portions 54 are provided in the regions other than the sliding portion 15, the present disclosure is not limited to such configuration. For instance, the holding portions 54 may be provided so as to overlap with the sliding portion 15 if the sliding portion 15 is disposed above the extension line L1 of the optical axis. Or, the sliding portion 15 may be disposed under the extension line L1 of the optical axis if the holding portions 54 are provided in regions other than the sliding portion 15.
Still further, while the case where the area S1 of the sliding portion 15 is provided to be larger than the area S2 totaling the regions of the shutter lever 4 overlapping with the holding portions 54 has been described in the exemplary embodiment described above, the present disclosure is not limited to such configuration. For instance, the area S1 may be smaller than the area S2.
Still further, while the sensor unit 10 is disposed under the developing sleeve 201 because the process cartridge 9 is provided above the intermediate transfer belt 24 in the exemplary embodiment described above, the present disclosure is not limited to such configuration. For instance, the sensor unit 10 may be disposed above the developing sleeve 201 in a case where the process cartridge 9 is provided under the intermediate transfer belt 24. In such a case, although the foreign substances from the developing unit 200 do not fall directly onto the sensor unit 10, the similar effect with the present exemplary embodiment can be obtained in a case where floating foreign substances infiltrate from the opening portion 6.
Still further, while the groove portion 12 is provided in the shutter lever 4 and the sliding boss 11 is provided in the shutter slider 3 in the configuration of the present exemplary embodiment, the similar effect with the present exemplary embodiment can be obtained even in a configuration in which the sliding boss is provided in the shutter lever 4 and the groove portion is provided in the shutter slider 3. In this case, as illustrated in
Still further, while the optical sensor has been the concentration sensor in the exemplary embodiment described above, the present disclosure is not limited to such configuration and the optical sensor may be a sensor that detects a color shift amount of images formed by each of the image forming units PY, PM, PC and PK. Still further, while the optical sensor has been configured to detect the toner image on the photosensitive drum 110 in the exemplary embodiment described above, the present disclosure is not limited to such configuration. For instance, the similar effect with the exemplary embodiment described above can be obtained by applying the inventive configuration even in a case where the optical sensor is configured to detect images formed on the intermediate transfer belt serving as an image bearing member.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-114839, filed Jul. 2, 2020, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2020-114839 | Jul 2020 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20090180803 | Tomita | Jul 2009 | A1 |
| 20090208245 | Sato | Aug 2009 | A1 |
| 20160313685 | Yamana | Oct 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 2011227244 | Nov 2011 | JP |
| 2015-143804 | Aug 2015 | JP |
| 20160036919 | Apr 2016 | KR |
| Number | Date | Country | |
|---|---|---|---|
| 20220004133 A1 | Jan 2022 | US |
