Patent Application
20180237252
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2017-032141 filed Feb. 23, 2017.
The present invention relates to a post-processing apparatus and an image forming apparatus.
In a post-processing apparatus and an image forming apparatus that perform a printing operation and post-processing on a printing sheet and eject the printing sheet, an ejection tray is provided in such a manner as to receive, for example, an ejected printing sheet.
In such apparatuses, in order to increase the number of recording media, such as ejected printing sheets, that are stackable on an ejection tray, the position of the ejection tray may sometimes be controlled in accordance with the number of the recording media stacked thereon by enabling the position of the ejection tray to move up and down.
However, in the case of enabling the ejection tray to move up and down by applying only a driving force with a driving source, such as a motor, the driving source needs to be capable of producing a driving force large enough for the ejection tray to move up and down, even in a state where the maximum stackable number of printing sheets or stacks of printing sheets are stacked on the ejection tray.
According to an aspect of the invention, there is provided a post-processing apparatus including an ejection tray receiving a recording medium that is ejected, an elastic member urging the ejection tray upward in a vertical direction, a moving mechanism causing the ejection tray to move up and down in the vertical direction, and a driving source driving the moving mechanism.
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
Exemplary embodiments of the present invention will now be described in detail below with reference to the drawings.
As illustrated in
A state in which the post-processing apparatus 10 is used by being connected to a printer 90 is illustrated in
The ejection tray 30 is fixed to the holding plate 32 and the rack member 33. The holding plate 32 is raised upward in the vertical direction and urged by a spring 36. In other words, the ejection tray 30 is urged upward in the vertical direction as a result of being raised by the spring 36, which is an elastic member. Note that the post-processing apparatus 10 is also provided with a spring 37 on the side opposite to the side on which the spring 36 is disposed, and a portion of the ejection tray 30, the portion being opposite to a portion of the ejection tray 30 that is urged by the spring 36, is also urged upward in the vertical direction by the spring 37.
When the motor 38 rotates, the gears 34 and 35 are driven so as to rotate. The rack member 33 has teeth that engage the gear 35 and is configured to move in the vertical direction along with rotation of the gear 35.
In the case where the moving mechanism, which is formed of the holding plate 32, the rack member 33, the gears 34 and 35, and the like, is not driven by the motor 38, the position of the ejection tray 30 moves in accordance with the total weight of the ejection tray 30 and printing sheets placed on the ejection tray 30.
A worm gear is a known example of the moving mechanism that causes the position of the ejection tray 30 not to move, even in a state where supply of power to the motor 38 is discontinued. In such a moving mechanism, the position of an ejection tray is controlled by using a worm gear having a large speed reduction ratio, so that the downward movement of the ejection tray may be hindered only by the moving mechanism.
However, the structure of a moving mechanism that uses a worm gear is complex, and thus, there has been a problem in that the manufacturing costs are high.
Accordingly, the post-processing apparatus 10 according to the present exemplary embodiment employs a moving mechanism that uses the normal gears 34 and 35 so as to simplify the structure of the moving mechanism and achieves a reduction in the manufacturing costs.
However, with such a moving mechanism that uses normal gears 34 and 35, as described above, when supply of power to the motor 38 is discontinued, there is a possibility that the position of the ejection tray 30 will move.
Consequently, the post-processing apparatus 10 according to the present exemplary embodiment includes a detector that detects the position of the ejection tray 30 when the ejection tray 30 moves up and down.
More specifically, as illustrated in
In other words, the rack member 33 and the optical sensor 41 form the detector, which detects the position of the ejection tray 30.
More specifically, when the rack member 33 is caused to move up and down by operating the gear 34, the current position of the ejection tray 30 may be determined from the width of one of the holes detected by the optical sensor 41. That is to say, for example, in the case where the ejection tray 30 is located at a position illustrated in
As illustrated in
In other words, in the case where supply of power to the motor 38 is discontinued and then restarted, the controller 60 estimates the total weight of printing sheets stacked on the ejection tray 30 on the basis of the position detected by the optical sensor 41 and controls the vertical movement of the ejection tray 30.
More specifically, the controller 60 detects the position of the ejection tray 30 by measuring the pulse width of a pulsed detection signal from the optical sensor 41 as illustrated in
In the case where the motor 38 is a stepping motor and where the controller 60 controls the motor 38 by outputting a pulsed signal to the motor 38, the controller 60 measures the pulse width of a detection signal from the optical sensor 41 by counting the number of pulses output to the motor 38.
Note that a configuration for detecting the position of the ejection tray 30 is not limited to the above-described configuration, and any configuration may be employed as long as the configuration enables detection of the position of the ejection tray 30.
A driving force of the motor 38 that is required for raising the ejection tray 30 and a driving force of the motor 38 that is required for lowering the ejection tray 30 will now be described with reference to
In
A case of performing a lowering operation for causing the ejection tray 30 to move downward will be described first with reference to
When the lowering operation is performed, the largest driving force of the motor 38 is required in the case where the weight of the printing sheets is small. That is to say, the load applied to the motor 38 becomes maximum.
In this case, the lowering force is expressed by the following equation 1.
lowering force=Fm+Mg−Fs (Equation 1)
The ejection tray 30 moves downward as the number of printing sheets stacked on the ejection tray 30 increases, and the pulling force Fs of the spring 36 gradually increases. When the force Fm of the motor 38 in a downward direction is larger than a force (Fs−Mg) obtained by subtracting the force Mg corresponding to the total weight of the ejection tray 30 and the printing sheets from the pulling force Fs of the spring 36, the ejection tray 30 may be lowered.
A case of performing a raising operation for causing the ejection tray 30 to move upward will now be described with reference to
When the raising operation is performed, the largest driving force of the motor 38 is required in the case where the weight of the printing sheets is large. That is to say, the load applied to the motor 38 becomes maximum.
In this case, the raising force is expressed by the following equation 2.
raising force=Fm+Fs−Mg (Equation 2)
Referring to Equation 2, it is understood that the ejection tray 30 and the printing sheets are pulled upward by the sum of the force Fm of the motor 38 in an upward direction and the pulling force Fs of the spring 36. In other words, when the total force (Fm+Fs) of the force Fm of the motor 38 in the upward direction and the pulling force Fs of the spring 36 is larger than the force Mg corresponding to the total weight of the ejection tray 30 and the printing sheets, the ejection tray 30 may be raised.
A folding structure of the ejection tray 30 will now be described with reference to
As illustrated in
Consequently, for example, when the post-processing apparatus 10 according to the present exemplary embodiment is packed and conveyed, the ejection tray 30 may be folded to the side on which the apparatus body is present as illustrated in
Note that, in a state where supply of power to the motor 38 is discontinued, the moving mechanism of the ejection tray 30 according to the present exemplary embodiment may be easily moved by an external force, and thus, the ejection tray 30 may be moved to a position at which an end of the ejection tray 30 is positioned below the top surface of the apparatus body by applying a force to the ejection tray 30 from above in a state where the ejection tray 30 is folded.
In the above-described exemplary embodiment, although a case has been described in which the present invention is applied to a post-processing apparatus, the present invention is not limited to such a post-processing apparatus. The present invention may also be applied to apparatuses, such as image forming apparatuses including printers and copying machines, each of which includes an ejection tray that receives an ejected printing sheet.
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 embodiments were 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 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-032141 | Feb 2017 | JP | national |
