Patent Grant
9193548
This application claims the benefit of priority to Japanese Patent Application No. 2013-201887 filed on Sep. 27, 2013, all of which is hereby incorporated by reference in its entirety.
The present disclosure relates to a sheet supply device for supplying a sheet like a paper, and an image forming apparatus.
The sheet supply device is widely applied to the image forming apparatus like the copying machine, the facsimile machine, the scanner, and the multifunction apparatus. Using the sheet supply device, the sheets like papers to transfer an original image thereon are conveyed one by one to a position to form the image thereon, whereby the image forming apparatus can print each image successively.
The sheet supply device is configured so that a sheet bundle abuts on a pickup roller in order that a plurality of sheets stacked onto a tray is fed one by one. A thickness of sheet bundle depends on the number of sheets stacked on the tray. Accordingly, a distance between a sheet stacking surface and the pickup roller should be adjusted according to the thickness of sheet bundle, in order to allow the sheet bundle to abut on the pickup roller properly. A lifting plate liftably mounted on the sheet stacking surface can be used for such adjustment. In the sheet supply device, the sheet bundle on the lifting plate is pushed up by the lifting plate, and the sheet bundle abuts on the pickup roller. The pickup roller sends out the sheet abutting on the pickup roller.
There are various kinds of techniques for materializing a stable sheet feeding in such sheet supply device. For instance, one configuration is disclosed wherein a torsion spring is employed as a lifting member for lifting up the lifting plate, and the elastic deformation of the torsion spring is changed depending on the paper remaining amount so that the force pushing up the lifting plate can be varied. In this configuration, it is possible to generate an almost constant feeding pressure (the force pushing sheet bundle against the pickup roller) regardless of the change of the loading weight from the full loading to the last sheet.
In addition, another configuration is disclosed wherein a plurality of elastic members is employed as the lifting member for lifting up the lifting plate. In such configuration, the force for lifting up the lifting plate can be varied by using an elastic member for generating a linear elastic force and the other elastic member for generating a non-linear elastic force.
Moreover, there is another configuration to suppress the conveyance skid by increasing the feeding pressure when the time for the fed sheet to arrive at the position to detect the paper arrival is longer than the specific time.
The image forming apparatus such as the printers has been requested to improve the image forming speed (the printing speed). On that account, since the sheet supply device is also needed to improve the paper feeding speed, the rotating speed (peripheral speed) of the pickup roller is increased. Where the rotating speed of the pickup roller is increased, the frictional force, which is generated between the pickup roller and the uppermost paper at the start of the pickup roller rotation, also tends to increase.
Moreover, there is a request of price reduction of the image forming apparatus, and it is considered that the cost of members composing the image forming apparatus is cut down. As the measure to down the cost, it is considered that the member made of metal is replaced with the member made of resin such as plastic. For instance, regarding the sheet supply device, it is considered that the member made of resin is used as the lifting plate uses.
When the resin member is applied to the lifting plate of the sheet supply device wherein the peripheral speed of the pickup roller is large as described above, however, the lifting plate is warped by the frictional force. When the warp is generated on the lifting plate in such way, the force for pushing the sheet bundle to the pickup roller is reduced. As a result, the paper feeding pressure is reduced, and the sheet cannot be sent out appropriately. That is to say, an interval between the drive start time of the pickup roller and the finishing time of the sheet feeding gets long. When it is determined that the lifting plate is to be lifted up because the warp occurs on the lifting plate and the force for pushing the sheet bundle to the pickup roller is reduced, the time is required for lifting the lifting plate, too. In this case, the interval between the drive start time of the pickup roller and the finishing time of the sheet feeding become longer than ever.
In the sheet supply device, in order to determine whether or not the sheet is conveyed normally, a sensor is disposed on the downstream side of the pickup roller, and the interval between the drive start time of the pickup roller and the detection time that the sensor detects the sheet fed by the pickup roller is measured. When the measured time is longer than a predetermined maximum time, it is determined the abnormal of sheet feeding (JAM). In the above-mentioned high-speed sheet supply device, there is a tendency that the maximum time is set to be short. Therefore, when the sheet feeding time gets long due to the warp of the lifting plate, the abnormality of sheet feeding is detected frequently.
Since the above-mentioned sheet conveyance failure is caused by the warp of the lifting sheet, even if the method for keeping the feeding pressure constant and the method for increasing the feeding pressure, as disclosed in the foregoing conventional arts, are applied to the sheet supply device, it is not possible to eliminate the sheet failure.
The sheet supply device related to the present disclosure includes a lifting plate, a driving unit, a pickup roller, a sensor, an abnormality detection unit and an abnormality detecting condition correction unit. The lifting plate is made of a flexible material and liftably mounted on a sheet stacking surface. The driving unit drives up and down the lifting plate. The pickup roller is placed above the lifting plate and feeds the sheet with abutting on an upper surface of the sheets loaded on the lifting plate. The sensor detects an arrival of the sheet fed by the pickup roller on a downstream side of the pickup roller. The abnormality detection unit detects a sheet feeding abnormality of the sheet fed by the pickup roller based on a drive start time of the pickup roller and a time sheet detection by the sensor. The abnormality detecting condition correction unit corrects an abnormality detecting condition of the abnormality detection unit depending on an amount of sheets loaded on the lifting plate.
The other aspect in accordance with the present disclosure provides an image forming apparatus including the above-mentioned sheet supply device.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
The embodiment of the present disclosure will be more specifically explained hereinafter according to the attached drawings. The present disclosure is materialized by a digital multifunction peripheral including a sheet supply device.
The image reading unit 120 is disposed below the original plate 103. The image reading unit 120 reads an image of an original by a scanning optical system 121, and creates digital data (image data) of the image. The original can be placed on the original plate 103 or the document feeder 110. The scanning optical system 121 includes a first carriage 122 and a second carriage 123, and a condenser lens 124. The first carriage 122 is provided with a linear light source 131 and a mirror 132, and the second carriage 123 is provided with mirrors 133 and 134. The light source 131 illuminates the original. The mirrors 132, 133 and 134 guide the light reflected on the original to the condenser lens 124, and the condenser lens 124 forms a light image on a light receiving surface of a line image sensor 125.
In the scanning optical system 121, the first carriage 122 and the second carriage 123 are mounted so as to reciprocate in a sub scanning direction 135. The image sensor 125 can read the image of the original placed on the original plate 103 by moving the first carriage 122 and the second carriage 123 in the sub scanning direction 135. In case of reading the image of the original placed on the document feeder 110, the image reading unit 120 temporarily stops the first carriage 122 and the second carriage 123 so as to correspond to an image reading position, and then reads the image of the original passing through the image reading position by the image sensor 125. The image sensor 125 creates the image data of the original corresponding to each color component of R (red), G (green), and B (blue) based on the light image incident to the light receiving surface, for example. The created image data can be printed out on the paper by the image forming unit 140. The image data also can be sent to other devices (not show) from network interface 161 via network 162.
The image forming unit 140 prints out on papers the image data obtained by the imager reading unit 120 or the image data received from the other device connected with the network 162. The image forming unit 140 is provided with a photosensitive drum 141. The photosensitive drum 141 rotates at a constant speed in one direction. A charging unit 142, an exposing unit 143, a developing unit 144, and an intermediate transfer belt 145 are arranged around the photosensitive drum 141 in order from an upstream side of the rotating direction of the photosensitive drum 141. The charging unit 142 uniformly electrifies a surface of the photosensitive drum 141. The exposing unit 143 irradiates light on the uniformly electrified surface of the photosensitive drum 141 according to the image data, and forms an electrostatic latent image on the photosensitive drum 141. The developing unit 144 adheres the toner to the electrostatic latent image and forms a toner image on the photosensitive drum 141. The intermediate transfer belt 145 transfers the toner image formed on the photosensitive drum 141 to the paper. When the image data is a color image, the intermediate transfer belt 145 transfers each color of the toner image to a same paper. The RGB form of color image is converted to the image data in a form of C (cyan), M (magenta), Y (yellow), and K (black), and each color component of the image data is inputted to the exposing unit 143.
The image forming unit 140 feeds a paper from a manual paper feed tray 151 or paper supply devices (sheet supply devices) 152 and 153 to a transfer unit between the intermediate transfer belt 145 and a transfer roller 146. The various size of papers can be placed on the manual paper feed tray 151 or be accommodated in the paper supply device 152 and 153. The image forming unit 140 selects the paper specified by user or the paper detected automatically corresponding to a size of original, and then feeds the selected paper from the manual paper feed tray 151 or the paper supply device 152 or 153 by a pickup roller 154. The fed paper is conveyed to the transfer unit by a conveyance roller 155, 156 and a resist roller 157. The paper on which the toner image is transferred is conveyed to a fixing unit 148 by a conveyance belt 147. The fixing unit 148 has a fixing roller 158 including a heater and a pressure roller 159, and the toner image is fixed on the paper by the heat and the pressure. The image forming unit 140 ejects the paper passing through the fixing unit 148 to a copy receiving tray 149. Besides, a sensor 160 is disposed nearby the upstream side of the resist roller 157 for detecting an arrival of the paper that is fed by the paper supply device 152 and 153. The sensor 160 can employ the reflective type photosensor (photo reflector) provided with a light emitting unit and a light receiving unit on the same surface, the contactless sensor such as transmissive type photosensor provided with the light emitting unit and the light receiving unit facing each other, or the contact type sensor such as the micro-switch.
The structure of the paper supply device 152 and 153 is explained hereinafter based on the paper supply device 152. The paper supply device 152 can accommodate papers P (appropriately referred to “a paper bundle”) therein. The paper bundle is loaded on a lifting plate 201 liftably mounted on the paper supply device 152.
As shown in
The paper supply device 152 includes a movable paper guide 211 for prohibiting the moving of the paper P loaded on the lifting plate 201. As shown in
As shown in
In the above-mentioned configuration, the paper bundle P loaded on the lifting plate 201 moves upward along the rotation of the plate lifting arm 203 as shown in
As shown in
As described above, where the peripheral speed of the pickup roller 154 is large and the lifting plate 201 has flexibility, the warp of the lifting plate occurs.
As shown in
When the warp occurs, the position of the floating end 201a of the lifting plate 201 moves downward and the frictional force between the paper bundle P and the pickup roller 154 reduces. As a result, the interval between the drive start time of the pickup roller 154 and the moving start time of the paper becomes long. Additionally, when the warp occurs, there is a possibility that a gap is generated between the lifting plate 201 and the plate lifting arm 203. If the gap is generated, there is a case where the frictional force between the paper bundle P and the pickup roller 154 gets lower and the abutting of the pickup roller 154 and the paper bundle P is not detected by the sensor 214. In such case, the plate lifting arm 203 is driven until the abutting of the pickup roller 154 and the paper bundle P is detected by the sensor 214. As a result, the interval between the drive start time of the pickup roller 154 and the moving start time of the paper gets longer than ever.
The internal path 406 is also connected with the operation panel 171 and various sensors 407. The operation panel 171 receives the user operation, and supplies a signal based on the operation to CPU 401. The operation panel 171 displays an operation screen on a display provide to the operation panel 171 according to the control signal from CPU 401. The sensor 407 includes various kinds of sensors, such as an open and shut detecting sensor for detecting the opening and the shutting of the platen cover 102, an original detecting sensor for detecting an original on the original plate 103, a temperature detecting sensor for detecting the temperature of the fixing unit 148, a paper detecting sensor for detecting the paper or the original to be conveyed, and so on. CPU 401 executes the programs stored in ROM 403, whereby the following means (functional blocks) can be realized and it is possible to control the working of each means according to the signals from these sensors.
The abnormality detection unit 501 detects the abnormality of the paper feeding by the pickup roller 154 based on a drive start time of the pickup roller 154 and a paper (sheet) detection time by the sensor 160. In this embodiment, an output signal of a pickup roller driving unit 511 for driving the pickup roller 154 and an output signal of the sensor 160 are inputted to the abnormality detection unit 501. The abnormality detection unit 501 acquires the drive start time of the pickup roller 154 based on the output signal of the pickup roller driving unit 511. And the abnormality detection unit 501 monitors whether or not the sensor 160 detects the paper conveyed from the pickup roller 154 until a predetermined normal time (see an abnormality detecting condition: “abnormality detection time” in
The abnormality detection unit 501, when the sensor 160 does not detect the paper until the normal time has passed, determines that the abnormality occurs at the paper feeding by the pickup roller 154. It is not limited in particular, in this embodiment, when detecting the abnormality, the abnormality detection unit 501 notifies a notification unit 513 of the abnormality occurrence. Upon receipt of the notice, the notification unit 513 notifies the user of the abnormality occurrence in an arbitrary way, such as by displaying a warning of notifying the abnormality on a display of the operation panel 171.
The abnormality detecting condition correction unit 502 corrects abnormality detecting conditions of the abnormality detection unit 501 according to the remaining amount of paper bundle P (sheets) loaded on the lifting plate 201. It is not limited in particular, the abnormality detecting condition correction unit 502 corrects the abnormality detecting conditions by adding a delay time α to the normal time.
The amount of paper bundle P is acquired from a paper remaining amount detection unit 512. The paper remaining amount detection unit 512 can employ a well-known arbitrary structure. For instance, the paper remaining amount detection unit 512 can execute the determination based on the position and upward moving amount of the lifting plate 201 and the position of the uppermost paper. In order to detect the positions, it is possible to use a photosensor like a photoreflector or photointerrupter, the other contactless type sensor, or the contact type sensor like the microswitch.
In addition, the abnormality detecting condition correction unit 502 in the embodiment corrects the abnormality detecting conditions of the abnormality detection unit 501 according to the use of pickup roller 154. As described above, the abnormality detecting condition correction unit 502 corrects the abnormality detecting conditions by adding the delay time β to the normal time. The dimension showing how frequently the pickup roller 154 is used can be expressed by an arbitrary parameter expressing the performance degradation (the reduction of the frictional force) by use. For instance, the number of papers conveyed by the pickup roller 154 (the number of printed sheets) may be used as the parameter. The total number of papers in long time use can be counted by a counter provided to the pickup roller drive unit 511.
In this embodiment, the abnormality detecting condition correction unit 502 adds a total delay time Tr=α+β to the normal time. Besides it can be considered that the warp of the lifting plate 210 would varies according to the lapsed time and the degree of use due to the time-based deterioration depending on the material of the lifting plate 210. Taking the time-based deterioration into consideration, for example, after multiplying the delay time α by a function k1(t) that expresses a dependency of the lapsed time and the degree of use, Tr=α×k1(t)+β may be added to the normal time as the total delay time. Likewise, it can be considered that the warp of the lifting plate 210 varies due to the temperature change depending on the material of the lifting plate 210. Taking the temperature change into consideration, for example, after multiplying the delay time α by a function k2(T) that expresses a temperature dependency, Tr=α×k2(T)+β may be added to the normal time as the total delay time. Furthermore, it is configured in
In
For instance, where the peripheral speed of the pickup roller 154 is 400 mm/s, the delay time caused by the frictional force between the paper bundle P and the pickup roller 154 is 40 ms, the theoretical distance that the paper is conveyed for the delay time is 16 mm. When the margin time is a time corresponding to 12 mm (30 ms), it is determined that the paper feeding is abnormal.
In
When the procedure starts, the abnormality detecting condition correction unit 502 acquires the number of conveyed papers through the pickup roller driving unit 511, and acquires the number of papers on the lifting plate 201 through the paper remaining amount detection unit 512 (step S801). The number of papers may be acquired by the paper remaining amount detection unit 512 at this time, or otherwise, it may be acquired in advance by the paper remaining amount detection unit 512.
The abnormality detecting condition correction unit 502 that acquired the number of conveyed papers and the number of papers on the lifting plate determines if the abnormality detecting condition (the normal time) registered in the abnormality detection unit 501 is necessary to be corrected or not (Step S802). Specifically, the abnormality detecting condition correction unit 502 calculates the delay time Tr, and determines that no correction is required when the time Tr is 0. When the delay time is not equal to 0, the abnormality detecting condition correction unit 502 determines that the correction is required.
When the correction of the abnormality detecting condition is required, the abnormality detecting condition correction unit 502 executes the correction by adding the delay time Tr to the normal time registered in the abnormality detection unit 501 (Step S802 YES, S803). When the correction of the abnormality detecting condition is not required, the abnormality detecting condition correction unit 502 notifies the abnormality detection unit 501 of no correction (Step S802 No).
At correcting the abnormality detecting condition by the abnormality detecting condition correction unit 502 or receiving the notice that no correction is required, the abnormality detection unit 501 detects the conveyance abnormality of conveying paper based on latest abnormality detecting conditions (Step S804). At this time, the pickup roller driving unit 511 increases the number of conveyed papers whenever the paper is conveyed.
The above processing is continued while the unprinted printing data exists (Step S805 Yes, S801). When the unprinted printing data does not exist, the procedure ends (Step S805 No).
As described above, in the multifunction peripheral 100, the abnormality detecting condition of the abnormality detection unit 501 is corrected depending on the number of papers loaded on the lifting plate 201. Specifically, in a situation that the warp occurs on the lifting plate, the normal time is extended depending on the feeding time increasing due to the warp. As a result, the detection of the abnormality can be executed without errors, and it is possible to suppress the productivity deterioration in the condition that the warp does not occur on the lifting plate. Additionally, since the extension time of the normal time is in minimum, when the feeding abnormality occurs in fact, the time of the feeding abnormality is not extended. For instance, when the paper jam occurs, it is possible to minimize the abrasion of the conveyance roller that is caused by continuously transmitting the driving force from the conveyance roller to the jammed papers.
Furthermore, in the embodiment, the skid caused by the abrasion of the pickup roller 154 is also reflected on the delay time Tr, so that it is possible to suppress the erroneous detection of the feeding abnormality more accurately.
Besides, the example that the delay time Tr is added to the normal time was explained in the above embodiment, but instead of changing the period of the normal time (the period between the time t1 and the time t3 in
Besides, the above embodiments do not limit the technical scope of the present disclosure, and other variations and applications can be made in accordance with the scope of the present disclosure, except the foregoing description. For instance, the multifunction peripheral 100 is configured so that the delay time Tr includes the delay time β reflecting the abrasion of the pickup roller 154, but including the delay time β is not indispensable. By correcting the abnormality detecting condition using at least the delay time α, the erroneous detection of conveyance troubles caused by the warp of the lifting plate can be suppressed.
With respect to the flowchart shown in
In the forgoing embodiments, the present disclosure is materialized as the paper supply device for the digital multifunction peripheral, but other than the digital multifunction peripheral, the present disclosure can be applied to the sheet supply device for any image forming apparatus provided with the printer, the copying machine, and the printing function. In addition, the present disclosure can be applied to the sheet supply device for feeding any sheets other than the papers.
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