Patent Application
20150125166
1. Field of the Invention
The present invention relates to a developer container, a developing apparatus, a process cartridge and an image forming apparatus.
2. Description of the Related Art
Developing assemblies that are used in image forming apparatuses such as electrophotographic printers or the like comprise ordinarily a developer container in which a developer (toner) is accommodated, and a developing roller, rotatably provided at an opening of the developer container, and which carries and transports the developer from inside the developer container. The developer inside the developer container is stirred through rotation of a stirring member that is provided inside the developer container, is transported by the developing roller, and is consumed thereupon by being used to develop an electrostatic latent image.
Herein, Japanese Patent Application Publication No. H3-271785 discloses, as a method for detecting a residual amount of the consumed developer from inside the developer container, a method that involves detecting the pressure (toner powder pressure) that the developer exerts on the stirring member. In the method disclosed in Japanese Patent Application Publication No. H3-271785, the stirring member is provided with a piezoelectric element, such that the residual amount of the developer is detected on the basis of changes in the developer pressure exerted on the piezoelectric element.
In the configuration of Japanese Patent Application Publication No. H3-271785, a plate-like polymer piezoelectric element is affixed to a paddle surface of a rigid stirring member. The polymer piezoelectric element detects, in the form of change of generated voltage, small changes in the pressure that the developer exerts on a piezoelectric surface, in the thickness direction. Changes in generated voltage arise as a result of deformation of the piezoelectric element. Herein, the deformation of the piezoelectric element derived from developer pressure in the thickness direction involves only deformation of contracting in the thickness direction. The resulting deformation amount is very small, and the changes in generated voltage are likewise extremely small. Accordingly, the sensitivity of the piezoelectric element, as a sensor, is very low, and detection precision is limited.
It is an object of the present invention to provide a technology that allows enhancing the detection precision of the residual amount of a developer.
To attain the above goal, a developer container of the present invention, comprising:
an accommodating portion in which a developer is accommodated;
a sheet-like stirring member that, by rotating, stirs the developer accommodated in the accommodating portion;
a piezoelectric element that is affixed to the stirring member and that outputs voltage, when being deformed; and
a deflection forming portion that comes in contact with the stirring member, thereby causing the stirring member to deflect, when a free end of the rotating stirring member is outside a developer accumulation region in the accommodating portion.
To attain the above goal, a developing apparatus of the present invention, comprising:
the developer container; and
a developer carrier, provided in an opening of the developer container, and carrying a developer.
To attain the above goal, a process cartridge of the present invention for performing an image forming process of forming an image, by way of a developer, on a recording medium, the process cartridge being configured so as to be detachably mounted to an apparatus main body of an image forming apparatus,
wherein the process cartridge comprises the developer container.
To attain the above goal, an image forming apparatus of the present invention in which an image is formed by a developer on a recording medium,
the apparatus comprising:
the developer container;
voltage detection means for detecting voltage that is outputted by the piezoelectric element; and
developer residual amount detection means for detecting a residual amount of the developer that is accommodated in the accommodating portion, on the basis of a voltage value detected by the voltage detection means, wherein
the developer residual amount detection means
detects the residual amount of the developer on the basis of
a reference voltage value, which is an output voltage value of the piezoelectric element detected by the voltage detection means upon occurrence of flexural deformation due to contact of the stirring member with the deflection forming portion, and
an effective value of an output voltage value of the piezoelectric element detected by the voltage detection means while the stirring member is passing through the accumulation region, from among output voltage values of the piezoelectric element outputted over one rotation of the stirring member.
The present invention succeeds thus in providing a technology that allows enhancing the detection precision of the residual amount of a developer.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Now, with reference to the drawings, the implementation of the present invention will be described below in detail in an illustrative manner based on embodiments. However, the sizes, materials, shapes, relative arrangements, and the like of components described in the embodiments should be appropriately changed in accordance with the configuration of an apparatus to which the invention is applied or with any of various conditions. That is, the scope of the invention is not intended to be limited to the following embodiments.
Herein, the term image forming apparatus (electrophotographic image forming apparatus) denotes an image forming apparatus in which an image is formed on a recording material (recording medium), by a developer (toner), as a result of an electrophotographic image forming process. Examples of the image forming apparatus include, for instance, electrophotographic copiers, electrophotographic printers (LED printers, laser beam printers and the like), electrophotographic fax machines and electrophotographic word processors, as well as multifunction machines (multifunction printers) of the foregoing. The term recording material denotes a material on which an image is formed, for instance recording sheets, OHP sheets and the like.
The term process cartridge denotes a member resulting from integrating, in the form of a cartridge, an electrophotographic photoconductor drum and at least one from among a charging device, a developing means and a cleaning means, as a process means that acts on the electrophotographic photoconductor drum. This process cartridge is configured to be detachably mounted to the main body of the image forming apparatus. In the explanation below, the term image forming apparatus main body (hereafter “apparatus main body”) denotes an apparatus configuration portion that results from excluding at least the process cartridge, the developing apparatus or the developer container from the configuration of the apparatus main body.
In
In the rotation process thereof, the OPC photoconductor 1 (hereafter, photoconductor 1) undergoes a charging process of being homogeneously charged, to a predetermined polarity (negative, in the present embodiment) and predetermined potential, by the charging roller 2 to which an oscillating voltage (VAC+VDC) is applied. The charging process surface of the photoconductor 1 undergoes scanning exposure by an exposure device 33, via a mirror 32. A laser beam emitted by the exposure device 33 is modulated in accordance with a time-series electric digital image signal, of the intended image information, as outputted by a laser scanner not shown. An electrostatic latent image corresponding to the intended image information becomes formed as a result on the surface of the OPC photoconductor 1.
Toner negatively charged by a developing sleeve 3 of a developing apparatus 8 is supplied to the electrostatic latent image formed on the photoconductor 1, and the electrostatic latent image becomes reverse-developed thereby. A predetermined developing bias from a high-voltage power source (not shown) is applied to the sleeve 3.
Meanwhile, a recording material (transfer material) 10 is fed, from a paper feed unit, not shown, to a contact nip section (transfer section) of the photoconductor 1 and a transfer roller 34, by way of a transfer guide 35, in concert with the timing of the toner image on the photoconductor 1. The toner image is transferred from the surface of the photoconductor 1 onto the surface of the recording material 10. A predetermined transfer bias from the high-voltage power source is applied to the transfer roller 34; thereby, the toner image is transferred on account of the transfer bias. The recording material 10 having passed through the transfer section is introduced into a fixing apparatus 30. The toner image undergoes there a fixing process, and is outputted in the form of an image formed product.
After transfer of the toner image to the recording material 10, the developer remaining on the photoconductor 1 is removed and recovered by a cleaning device 6.
In the present embodiment, four process devices in the above configuration, namely the photoconductor 1, the charging roller 2, the developing apparatus 8 and the cleaning device 6 are configured integrally in the form of the process cartridge 36, so as to be detachably mounted to an apparatus main body 40 of the image forming apparatus. The cartridge configuration is not limited to the configuration disclosed herein, and it suffices that the cartridge be provided with at least one from among the photoconductor 1, the charging member 2, the developing apparatus 8 and the cleaning device 6.
The process cartridge 36 has a slit window hole through which a laser beam from the exposure device 33 is incident, and an opening and closing shutter unit (not shown) facing the exposed section on the underside of the photoconductor 1. These openings are configured so as to remain closed while the process cartridge 36 is removed from the apparatus main body 40, and to remain open while fitted to the apparatus main body 40. When the process cartridge 36 is fitted to the apparatus main body 40, the process cartridge 36 becomes mechanically and electrically coupled to a driving mechanism that is provided on the apparatus main body 40 side. As a result, this enables driving of, for instance, the photoconductor 1 or the developing sleeve 3 of the developing apparatus 8, and allows a predetermined bias to be applied to the charging roller 2, the developing sleeve 3 and the like, from a power source on the apparatus main body 40 side.
<Developing Apparatus>
The developing sleeve 3 is a non-magnetic developer carrier having a built-in fixed magnet 31. The developing sleeve 3 is rotatably provided in an opening, of the developer container 8a, that is provided at a position opposing the photoconductor 1 (
The elastic blade 4 is fixed to an opening of the developer container 8a in such a way so as to come in contact with the surface of the developing sleeve 3, and regulate the amount of toner 5 that is carried and transported by the developing sleeve 3. The elastic blade 4 regulates the thickness of the toner 5 on the developing sleeve 3, to form a developer layer (toner layer) of a predetermined thickness. The layer of toner 5 thus formed is transported, accompanying the rotation of the developing sleeve 3, to a developing section that is formed by the developing sleeve 3 and the photoconductor 1, to develop the electrostatic latent image that is formed on the photoconductor 1.
The stirring member 11 is provided so as to be rotatable about a rotary shaft 11a. The toner 5 inside the developer container 8a is loosened and caused to circulate throughout the interior of the developer container 8a by the rotating stirring member 11. A configuration is achieved as a result wherein degradation of the toner 5 is suppressed, and the toner 5 inside the developer container 8a can be consumed thoroughly.
The stirring member 11 is a flexible sheet-like member configured so as to deform on account of resistance from the toner 5 during rotation. Deformation of the stirring member 11 is detected by a piezoelectric element 12, as a detection member, that is attached to the stirring member 11. A reference-setting projection 9, as a deflection forming portion, is provided, inside the developer container 8a, at a region outside (above) a accumulation region of the toner 5, in such a manner that the reference-setting projection 9 can come in contact with the rotating stirring member 11. The term accumulation region of the toner 5 denotes herein a region at which most of the toner 5 accumulates in the interior (accommodating portion) of the developer container 8a in a static manner, without floating up or splashing, during normal use. The rotary shaft 11a of the stirring member 11 is preferably in a state of not being buried within the accumulation region of the toner 5, from the viewpoint of detection precision. However, the rotary shaft 11a, or the root side of the stirring member 11, which exhibits a relatively small deformation amount, may be in a state of being slightly buried within the accumulation region, so long as deformation of the leading end side of the stirring member 11, the deformation amount whereof is relatively large, is not affected thereby, i.e. so long as detection precision is little affected.
<Configuration of the Stirring Member and the Piezoelectric Element>
An explanation follows next with reference to
The stirring member 11 is a sheet-like member made up of a resin such as polyphenylene sulfide (PPS) or polyethylene terephthalate (PET). The stirring member 11 has a thickness of 150 μm, so as to be flexible while exhibiting a sufficient elastic restoring force towards bending stress.
A piezo film (by Tokyo Sensor Co., Ltd.), which is a polymer piezoelectric element, is used as the piezoelectric element 12 in the present embodiment. As illustrated in
In the present embodiment, as illustrated in
As described above, the sheet-like stirring member 11 is configured in such a manner that the leading end thereof is a free end that can undergo significant bending deformation. The piezoelectric element 12, in the form of the piezo film, is disposed in the stirring member 11 in such a manner that the piezoelectric element 12 deflects significantly in the rolling direction, in which the piezoelectricity of the piezo film is large. As a result, the flexural deformation of the stirring member 11 is converted to a large elongation deformation of the piezo film in the rolling direction, and hence very small changes in toner powder pressure can be detected through conversion, into large voltage changes, by the piezo film having a comparatively small area.
<Reference-Setting Projection>
The reference-setting projection 9 provided inside the developer container 8a will be explained next. The film-like piezoelectric element 12 has a temperature characteristic, and thus the voltage outputted by the piezoelectric element 12, on account of deflection of the stirring member 11, may in some instances vary significantly depending on differences in environmental temperature. The piezoelectric element 12 is film-like and is hence prone to exhibit large variability in mounting precision. This variability when the piezoelectric element 12 is bonded exerts in turn an influence on sensitivity, and the output voltage may vary significantly as a result. The purpose of the reference-setting projection 9 is to deliberately bring about a deflection state while the stirring member 11 is in a state of not being influenced by toner powder pressure, so as to detect the toner powder pressure, taking as a reference the output voltage value detected by piezoelectric element 12 at that time. The reference-setting projection 9 protrudes beyond the wall of the developer container 8a, so as to overlap with the movement region of the stirring member 11, outside the accumulation region of the toner 5 in the interior of the developer container 8a.
In the present embodiment, the reference-setting projection 9 is provided at the top of the interior of the developer container 8a, as illustrated in the figures. The reason for providing the reference-setting projection 9 at the top of the developer container 8a is to cause the piezoelectric element 12 to output a reference voltage value, by imparting deflection to the stirring member 11 and the piezoelectric element 12, while the latter are unaffected by the toner inside the container. Using this reference voltage value allows correcting the output voltage value of the piezoelectric element 12, even upon changes in the sensitivity thereof, derived from environmental fluctuations or the like, as described above.
In the present Embodiment 1, the reference-setting projection 9 that protrudes down from the ceiling of the developer container 8a is provided for obtaining a reference voltage value, but the embodiment does not necessarily need to resort to a configuration where such a projection is provided.
<Toner Residual Amount Detection Method>
As illustrated in
As illustrated in
An effective value Vave of a serial output waveform generated in the stirring period is detected by an effective value detection circuit (S23). Thereafter, a CPU determines a toner residual amount on the basis of a relationship, prepared beforehand, between the toner residual amount and the output voltage of the piezoelectric element 12 (S24). The CPU notifies the residual amount to a user (S25), and brings the image forming apparatus to a printing queue state (S26).
In the present embodiment a toner residual amount is detected by using a voltage peak value generated by the piezoelectric element 12 when the stirring member 11 contacts the reference-setting projection 9, and a voltage effective value that is generated by the piezoelectric element 12 while the stirring member 11 is immersed in the toner. In the present embodiment, a voltage detection means in the form of the peak detection circuit 13 and the effective value detection circuit 14 is connected to the piezoelectric element 12, such that a CPU 15, as a developer residual amount detection means, detects the toner residual amount on the basis of voltage values outputted by these circuits. The CPU 15 is also a control means for controlling the various operations of the image forming apparatus. The image forming apparatus is provided with a storage means in the form of a ROM, a RAM and the like, such that the CPU 15 performs various control processes by drawing on information stored in these memories and that is necessary for various computations.
The operating conditions in toner residual amount detection are identical to those in the above-described conventional configuration, as illustrated in
As illustrated in
The effective value detection circuit 14 detects the effective value Vave within a range in the serial output waveform that are generated in one period T of stirring (see
The reason for computing Vave/Vmax will be explained next. The temperature-voltage output characteristic of the film-like piezoelectric element 12 exhibits a substantially linear proportional relationship. Accordingly, a rise in temperature translates into a rise also of the effective value that is used in residual amount detection, which may preclude accurate residual amount detection. In some instances, moreover, the sensitivity may vary depending on the way in which the piezoelectric element 12 is mounted to the stirring member 11, such that the signal of residual amount detection exhibits variability for identical toner residual amounts. Accordingly, the outputted voltage values are normalized (Vave/Vmax) using a peak voltage value as a reference, to enable thereby residual amount detection excluding the influence of error derived from temperature changes and element mounting.
The timing of the residual amount detection in the present embodiment is designated as described above, but the detection timing is not particularly limited. The detection timing may be immediately before or immediately after the printing operation, but is preferably other than during printing. In the present embodiment, the toner residual amount is determined through sampling of output values at each period T of stirring, but any period may be relied upon for sampling, so long as the peak value derived from the reference-setting projection 9 can be compared with an effective value associated with the toner residual amount.
A durability experiment according to a conventional residual amount detection method and the residual amount detection method of the present embodiment was performed in order to compare the foregoing two methods. The durability test conditions included environment conditions of 10° C., 20° C. and 30° C., under which there was measured a profile of the toner residual amount as detected in accordance with the respective method. The experiment results are illustrated in
In a conventional method, as illustrated in
A developer container according to Embodiment 2 of the present invention will be explained next with reference to
In a configuration where part of the wall of the developer container 8a, such as the reference-setting projection 9 of Embodiment 1, is caused to protrude, a toner jam may arise at the reference-setting position, as illustrated in
As a characterizing feature of Embodiment 2, a reference shaft 17 that extends in the longitudinal direction of the developer container 8a (direction perpendicular to the paper in
The configuration for preventing splattered toner from remaining at the reference-setting position is not limited to providing the reference shaft 17, as in the present embodiment. For instance, an effect identical to that of the present embodiment may be accomplished by providing through-holes in the reference-setting projection 9 of Embodiment 1, such that splattering toner can pass through the holes.
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. 2013-229714, filed on Nov. 5, 2013, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-229714 | Nov 2013 | JP | national |
