This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-066881 filed on Mar. 18, 2009.
1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
Among image forming apparatuses such as copiers and printers using electrophotography or the like, an image forming apparatus of a so-called process cartridge type is known in which replacement parts such as a photoreceptor drum, a charging device and a developing device are integrated into a unit so that the user can detachably attach the unit to the image forming apparatus body
According to an aspect of the invention, an image forming apparatus comprises: a housing that is fixedly placed in the image forming apparatus and integrally accommodates an imaging portion that includes at least an image holding member; a transferring unit that is disposed against the image holding member so that the transferring unit is capable of pressing and separating the image holding member; and a high-voltage power supplying unit that supplies a high voltage, wherein a power supplying path that is formed on an outer surface of the housing so that the high voltage is supplied from the high-voltage power supplying unit to the imaging portion and the transferring unit via the power supplying path.
Exemplary embodiments of the invention will be described in detail based on the following figures, wherein:
Hereinafter, an exemplary embodiment of the present invention will be described with reference to
As shown in
On the back side of the apparatus body 100, a jam processing cover 100C formed so as to be rotatable about the a rotation support 100C0 is provided for so-called jam processing performed when a paper jam or the like occurs. Specifically, in an upper part of the jam processing cover 100C, an operation button 100P is provided in a substantially central part in the direction of the length, and the jam processing cover 100C can be opened and closed by pressing (pushing up) the operation button 100P.
In the present exemplary embodiment, the jam processing cover 100C is interlocked with a non-illustrated power switch so that no apparatus power is supplied (the apparatus is turned oft) when the cover 100C is opened.
Further, in the printer 1 according to the present exemplary embodiment, as most clearly shown in
As shown in
The electrostatic latent image formed on the photoreceptor drum 3 is developed into a toner image by the developing device 6 as the developing unit, and the toner image is transferred onto a recording sheet 8 as a recording medium by the transferring roll 7 as the transferring unit. As the recording sheet 8, one of a predetermined size and a predetermined material is supplied from the paper feeding tray 9 by a pair of paper feeding rolls 10 in a condition of being separated sheet by sheet, and is conveyed to the transfer position of the photoreceptor drum 3 through a non-illustrated resist roll at a predetermined timing.
In the present exemplary embodiment, as most clearly shown in
Specifically, as shown in the enlarged view of
The recording sheet 8 having the toner image transferred thereonto is separated from the surface of the photoreceptor drum 3, and then, conveyed to the fixing device 11. Then, the unfixed toner image is fixed onto the recording sheet 8 by heat and pressure by the fixing device 11, and the recording sheet 8 is ejected onto an output tray 13 provided at the upper end of the printer body 1 by paper ejecting rolls 12 with the image formed surface facing downward.
The untransferred remaining toner not transferred onto the recording sheet 8 but remaining on the surface of the photoreceptor drum 3 is removed by the cleaning blade of a cleaning device 15.
Next, the structure of the process unit 2 as the imaging portion according to the present exemplary embodiment will be described with reference to
As shown in
Specifically, the transferring roll holding portions 20F each have, as schematically shown in
The positioning portion 20Fp of the transferring roll holding portions 20F according to the present exemplary embodiment is constituted by a horizontal surface 20Fph and a vertical surface 20Fpv, and by disposing the transferring roll 7 so that the peripheral surface at both ends in the axial direction of the rotation shaft 7s of the transferring roll 7 is in contact with the horizontal surface 20Fph and the vertical surface 20FpV, the holding position (hereinafter, also referred to as contact position) of the transferring roll 7 is set so that a predetermined pressing force to the photoreceptor drum 3 is obtained. That is, in the printer 1 according to the present exemplary embodiment, by using tracking rolls for bringing the transferring roll 7 into contact with the photoreceptor drum 3 at both ends of the transferring roll 7 without providing on the side of the jam processing cover 100C a pushing member for applying a pressing force for pressing the tracking roll against the photoreceptor drum 3, the predetermined pressing force to the photoreceptor drum 3 is obtained only by the above-described positioning of the transferring roll 7, and this enables a simple structure of the jam processing cover 100C.
On the other hand, when the jam processing cover 100C is opened, by pushing down the operation button 100P, the rotation of the jam processing cover 100C in the opening direction (in this example, in the clockwise direction) is enabled at the point of time when the transferring roll 7 climbs over the lower end 20Ft0 of the transferring roll holding portions 20F.
Moreover, as most clearly shown in
On the other hand, as most clearly shown in
In the present exemplary embodiment, the developing device 6 is disposed in the opening provided on the side of the photoreceptor drum 3 so that a developing roll 6R as a developer holding member is rotatable in the direction of the arrow, and on the back side of the developing roll 6R, developer agitating and conveying unit such as a supplying paddle 6a, a supplying auger 6b and an agitating auger 6c for supplying developer to the developing roll 6R while agitating it is provided. While the developer may be either a one-component developer containing only toner or a two-component toner containing toner and carrier, in the present exemplary embodiment, a two-component developer containing toner and carrier is used.
At the time of imaging (image formation), predetermined high-voltages, that is, a charging voltage, a developing voltage and a transferring voltage are applied from the high-voltage unit HV to the charging device 4, (the developing roll 6R of) the developing device 6 and the transferring roll 7 according to the present exemplary embodiment at a predetermined timing through a high-voltage power supplying path.
Next, the structure of the high-voltage power supplying path according to the present exemplary embodiment will be further described with reference to the drawings.
As shown in
Specifically, as most clearly shown in
Power supplying paths PLa and PLb according to the present exemplary embodiment are formed from the connection terminals 20Ta and 20Tb to the neighborhood of the corresponding devices to be supplied with power, along the outer surface of the unit case 20.
Reference designation TDp represents a power supplying terminal for the developing roll 6R provided in the separate development housing 6H attached to the lower part of the unit case 20. Reference designation TDn represents a spring terminal for the nip pressure for applying the pressing force of the developing roll 6R to the photoreceptor drum 3. In the present exemplary embodiment, from the viewpoint of uniformly applying the pressing force to the photoreceptor drum 3 in the axial direction, a nip pressure spring terminal TDn similar to the above-mentioned nip pressure spring terminal TDn is provided at the other end in the axial direction.
In the present exemplary embodiment, the power supplying path PLa for the charging device 4 that enables the power supply to the charging device 4 is disposed (laid) from the connection terminal 20Ta integrally formed in a coil form on the back surface of the unit case 20 to the neighborhood of the charging device 4 along the outer surface (in this example, the back surface and a side surface) of the unit case 20, by using a corresponding conductive wire material WRa.
On the other hand, the power supplying path PLb for the transferring roll 7 according to the present exemplary embodiment is disposed (laid) from the connection terminal 20Tb integrally formed in a coil form on the back surface of the unit case 20 to the neighborhood of the photoreceptor drum 3 along the outer surface (in this example, the back surface and the side surface) of the unit case 20, by using a corresponding conductive wire material WRb. Further, in the unit case 20 according to the present exemplary embodiment, a cylindrical support 20P formed so as to protrude in the axial direction is provided on the side surface in the neighborhood of the photoreceptor drum 3 (in this example, the side surface below the rotation shaft of the photoreceptor drum 3). The conductive wire material WRb is disposed from the side surface of the unit case 20 to the support 20P along the surface of the unit case 20, and then, wound at the support 20P. Then, an end WRt of the conductive wire material WRb is in contact with the conductive rotation shaft 7s of the transferring roll 7 therebelow.
More specifically, the conductive wire material WRb is disposed so that the end WRt thereof is opposed to the transferring roll holding portions 20F of the unit case 20 with the transferring roll 7 in between, and is wound around the support 20P so as to form a torsion spring that pushes the transferring roll 7 in a direction in which it is situated in the predetermined contact position in the positioning portion 20Fp of the unit case 20 (in
Moreover, by providing the transferring roll holding portions 20F on the downstream side of the transferring roll 7 in the rotation direction of the photoreceptor drum 3 (by disposing the contact position in the positioning portion 20Fp and the end WRt of the conductive wire material WRb so as to be opposed to each other with the transferring roll 7 in between), the dropping off of the transferring roll 7 from the positioning portion 20Fp and the position fluctuations thereof incident to the rotation of the photoreceptor drum 3 can be effectively suppressed.
In the present exemplary embodiment, from the viewpoint of supporting the transferring roll 7 by uniformly pressing it in the axial direction against the photoreceptor drum 3, although not shown, a similar support 20P is provided on the opposite side surface of the unit case 20, a similar wire material WR is wound around the support 20P, and by the end portion WRt thereof, the other end portion in the axial direction of the transferring roll 7 is supported.
Moreover, in the unit case 20 according to the present exemplary embodiment, for example, as shown in
In the printer 1 structured as described above, since the conductive wire material WR constituting the high-voltage power supplying path can be arbitrary disposed along the outer surface of the unit case 20 to the neighborhood of the component devices to be supplied with power, compared with the related structure in which the high-voltage power supplying path is provided in the unit case 20, it is unnecessary to dispose the power supplying path so as to avoid the rotation shafts of rotary members such as the photoreceptor drum 3, the charging roll 4, the developing roll 6R and a toner conveying member and the component members such as the toner accommodating portions and provide a complicated power supplying path in consideration of separation from members such as the charging roll 4 and the developing roll 6R to which a high-voltage is applied and grounded members such as the photoreceptor drum 3. Thereby, the degree of freedom of the setting of the power supplying path can be significantly increased, and the power supplying path can be simplified. Moreover, compared with the related structure in which the high-voltage power supplying path is provided in the unit case 20, it is unnecessary to secure an extra space inside the process unit 2 in consideration of separation from members such as the charging roll 4 and the developing roll 6R to which a high-voltage is applied and grounded members such as the photoreceptor drum 3. Thereby, the size of the process unit 2 can be reduced while the disposition of the component members in the unit case 20 is facilitated.
Moreover, since the power supplying path PLb according to the present exemplary embodiment is capable of easily supplying a predetermined high voltage also to the transferring roll 7 capable of being brought into contact with and separated from the photoreceptor drum 3 in synchronization with the jam processing cover 100C as described above and the rotation shaft 7s of the transferring roll 7 can be held in the predetermined position at both ends in the axial direction by the end portions WRt of the conductive wire material WRb wound around the support 20P, the predetermined position of the transferring roll 7 that applies the predetermined pressing force to the photoreceptor drum 3 can be maintained with stability. That is, the conductive wire material WRb according to the present exemplary embodiment not only functions as the power supplying path PLb to the transferring roll 7 but also performs the function as the holding unit for holding the transferring roll 7 in the predetermined position together with the transferring roll holding portions 20F of the unit case 20, and can contribute to size reduction and cost reduction consequent on reduction in the number of parts. The function as the holding unit is an additional function, and it is unnecessary to hold the transferring roll 7 only by the power supplying path PLb and the transferring roll holding portions 20F but different means may be used also for that purpose. However, it is undesirable to structure the transferring roll 7 so as to be in a direction opposite to the direction in which the transferring roll 7 is held in the predetermined position (direction that separates the transferring roll 7 from the predetermined position); since it becomes necessary to strengthen or increase the different means for holding the transferring roll 7 in the predetermined position, size reduction and cost reduction cannot be achieved.
Moreover, since the direction in which the transferring roll 7 is pressed against the photoreceptor drum 3 and the direction of connection between the connection terminal 20T of the process unit 2 and the high-voltage unit HV are substantially the same, when the transferring roll 7 is brought into contact and separated, the position shift between the high-voltage unit HV and the connection terminal 20T can be prevented, so that stable connection between the high-voltage unit HV and the process unit may be ensured.
While as the high-voltage power supplying path PL, the power supplying paths PLa and PLb to the charging roll 4 and the transferring roll 7 are shown as an example in the present exemplary embodiment, according to the power supplying path PL of the present invention, even when an arbitrary high-voltage device (for example, a charge removing and charging device that removes charge from the photoreceptor drum 3, or a cleaner that electrically removes toner from the photoreceptor drum 3) is added into the unit case 20, a power supplying path PL for such a high-voltage device maybe easily added. Consequently, the degree of freedom of design is significantly increased.
The technical scope of the present invention is not limited to the above-described exemplary embodiment, but various modifications or improvements may be made without departing from the purport of the present invention. For example, while in the above-described exemplary embodiment, the structure of the power supplying path according to the present invention is described with a monochrome black-and-white printer as an example, it is to be noted that such a power supplying path may be applied to color image forming apparatuses having a plurality of image forming units.
The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments are chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various exemplary embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
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