Patent Application
20100329759
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-151234 filed on Jun. 25, 2009.
(i) Technical Field
The present invention relates to a sheet length measuring apparatus, an image forming apparatus, and a sheet length measuring method.
(ii) Related Art
There has been conventionally known an art that detects a sheet length of a sheet on which an image is formed.
According to an aspect of the present invention, there is provided a sheet length measuring apparatus including: a rotating body that rotates in contact with a sheet delivered through a delivery path; detecting units that are located upstream and downstream of the rotating body respectively, and detect a position of the sheet delivered through the delivery path; a delivery unit that is located in at least one of positions between the detecting unit located upstream and the rotating body, and between the detecting unit located downstream and the rotating body, and delivers the sheet on the delivery path; and a rotation amount detecting unit that detects a rotation amount of the rotating body with using a period when the sheet is detected by the detecting units respectively located upstream and downstream of the rotating body as a measurement period.
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
A description will now be given, with reference to the accompanying drawings, of exemplary embodiments of the present invention.
(Description of an Example of a Composition of a Length Measuring Device)
A composition of a length measuring device 100a in accordance with this exemplary embodiment will be described with reference to
In addition, the rotating shaft 102a of the length measuring roll 101a is installed at one end of a swing arm 104a. The swing arm 104a keeps the rotating shaft 102a of the length measuring roll 101a rotatable. Another end of the swing arm 104a is attached to a swing arm supporting member 106a by a swing shaft 105a so that it is rotatable (swingably). The swing arm supporting member 106a is fixed to a chassis (not shown) of the length measuring device 100a.
An extension arm 107a is provided at the end of the opposite side to the side of the swing arm 104a in which the length measuring roll 101a is installed. One end of a coil spring 108a is attached to this extension arm 107a. Another side of the coil spring 108a is attached to an arm 109a that extends from the swing arm supporting member 106a. The coil spring 108a is tensioned, and generates the force to rotate the swing arm 104a in a counterclockwise direction in
The delivery path that delivers the paper 150 is provided with the lower chute 112a and an upper chute 113a that are located to face each other. The upper chute 113a is located in the position with predetermined clearance from the lower chute 112a. The lower chute 112a and the upper chute 113a are planar members respectively, and have a function to control the paper 150 being delivered. The paper 150 is delivered in contact with the lower chute 112a, and is controlled by the upper chute 113a so that the paper 150 is not displaced upward.
The paper 150 is a sheet-shaped record medium (a record sheet), and is a paper material on which an image is formed. In addition to paper materials, resin materials used for OHP sheets and paper sheets of which surfaces are coated with resin can be used as materials that compose the record medium.
An upstream edge sensor (a detecting unit) 110a is located upstream of the length measuring roll 101a, and a downstream edge sensor (a detecting unit) 111a is located downstream. Here, the paper 150 is delivered through the delivery path from the upstream edge sensor 110a side to the downstream edge sensor IIIa side. Therefore, the sensor located on the more upstream side than the length measuring roll 101a in the paper delivery direction is called an upstream edge sensor 110a, and a sensor located on the more downstream side than the length measuring roll 101a is called the downstream edge sensor 111a in the paper delivery direction.
The upstream edge sensor 110a and the downstream edge sensor 111a are photoelectronic sensors composed of an LED (Light Emitting Diode) and a photo sensor, and detect the passage of the delivered paper 150 at a detection position optically. Sensor signals output from the upstream edge sensor 110a and the downstream edge sensor 111a is transmitted to the controller 200. The controller 200 is a computer, and has a function that calculates a length of the paper 150 in the delivering direction, and a function as a controller of an image forming apparatus described later. These functions will be described later.
In addition, as illustrated in
The delivery roll 122a of the upstream delivery roll 120a and the delivery roll 132a of the downstream delivery roll 130a are driven by a motor (not shown). In addition, the delivery roll 121a and the delivery roll 131a rotate with drive force of the delivery roll 122a and the delivery roll 132a respectively.
The length measuring roll 101a can be located in the side where the delivery rolls 122a and 132a are located against the paper 150 (the lower side than the paper 150 in
(Description of an Example of a Composition of an Image Forming Apparatus)
An example of an image forming apparatus 300 including the length measuring device 100a is illustrated in
(Description of an Example of a Composition of a Paper Feeding Unit)
The paper feeding unit 310 is provided with a paper storage device 311 that stores multiple papers, a ejecting mechanism (not shown) that ejects papers to the delivery direction (to the image forming unit 320 side) from the paper storage device 311, and a delivery roll 312 that delivers papers ejected from the ejecting mechanism to the image forming unit 320.
(Description of an Example of a Composition of an Image Forming Unit)
The image forming unit 320 is provided with a delivery roll 321 which delivers the paper ejected from the paper feeding unit 310 to the inside of the image forming unit 320. A delivery roll 322 that delivers the paper 150, which is delivered by the delivery roll 321 or a delivery roll 332 described later, toward a second transfer unit 323 on a delivery path 324 is located upstream of the delivery roll 321. The second transfer unit 323 includes a transfer roll 326 and an opposite roll 327. The second transfer unit 323 transfers a toner image formed on a transfer belt 325 to the paper 150 by holding the transfer belt 325 and the paper 150 between the transfer roll 326 and the opposite roll 327.
The fixing unit 400 that fixes the toner image on the paper 150 to the paper 150 by heating and pressurization is located downstream of the second transfer unit 323. A delivery roll 328 is located downstream of the fixing unit 400. The delivery roll 328 delivers the paper 150 delivered by the fixing unit 400 to the outside of the device or a delivery roll 329.
When forming images on the both side of the paper 150, the delivery roll 328 delivers the paper 150 toward the delivery roll 329 after finishing forming the image on the first side of the paper 150. The paper 150 is delivered to a reversing device 330 by the delivery roll 329. The reversing device 330 returns the delivered paper 150 toward the delivery roll 329, and the delivery roll 329 delivers the paper 150 returned from the reversing device 330, to a delivery path 331.
The length measuring device 100a illustrated in
Controls of a primary transfer processing and a second transfer processing of the image formed on the second side are executed on the basis of the length in the delivery direction of the paper measured by the length measuring device 100a. This is to reduce the phenomenon that the forming position of the image to be formed on the second side is displaced because of the dimensional change of the paper caused by the influence of the image formed on the first.
The image forming unit 320 includes primary transfer units 341, 342, 343, and 344. These primary transfer units 341 to 344 are provided with a photoconductor drum, a cleaning device, a charging device, an exposure device, a developing device, and a transfer roll respectively. Primary transfer units 341 to 344 transfer toner images of Y (Yellow), M (Magenta), C (Cyan), and K (Black) to the transfer belt 325 which is rotating, one by one on top of the other. A color toner image composed of YMCK toner images is formed on the transfer belt 325.
The control of the behavior of each component described above is executed by the controller 200. The controller 200 also executes the processing to measure the paper length. The controller 200 executes a control of the image forming processing based on the measured paper length, in time of the image forming processing to the second side in the case that the images are formed on the both sides of the paper.
In the composition illustrated in
(Description of an Example of a Composition of a Control System)
A control system of the image forming apparatus 300 illustrated in
An example of the connection configuration of the controller 200 will be described with reference to
The operating unit 350 receives operating information input by the user. The operating unit 350 outputs the received operating information to the controller 200. The operating information includes the setting of a one-side printing or a duplex printing, and the setting of the number of printing, for example.
The image data receiving unit 351 acts as an input unit that receives the image data transmitted to the image forming apparatus 300 through the communication line (e.g. LAN) not shown. The image data receiving unit 351 outputs the received image data to the controller 200.
The upstream edge sensor 110a and the downstream edge sensor 111a detect the paper 150 delivered through the delivery path, and output a sensor signal that is ON while the paper 150 is detected, to the controller 200. The rotary encoder 103a generates a pulse signal with respect to each predetermined rotating angle when the length measuring roll 101a rotates. The pulse signal that the rotary encoder 103a outputs is also output to the controller 200.
Then, a device that is controlled by the controller and executes the image forming processing will be described.
The main motor drive control circuit 361 is a control circuit that controls a motor that rotates the transfer belt 325 in
The power circuit 362 is provided with a power circuit for developing bias 363, a power circuit for a charging device 364, a power circuit for transferring bias 365, and a power circuit for a fixing heater 366. The power circuit for developing bias 363 generates the bias voltage energized in the time when the toner is provided from a developing device to a photo conductor in primary transfer units 341 to 344 in
The delivery roll drive control circuit 367 is a drive circuit that drives a motor that moves a roll of a ejecting mechanism to deliver the paper such as the delivery roll 322.
A hardware composition of the controller 200 will be described with reference to
Then a functional block of the controller 200 implemented by the program control will be described with reference to
The paper length calculation part 211 has a calculation function to calculate the paper length, and stores the data processed with this calculation function in the RAM 203. The RAM 203 stores the data on a rotation amount of the length measuring roll 101a, the size data of the length measuring roll 101a, output information of the upstream edge sensor 110a and the downstream edge sensor 111a, information about the inter-sensor distance between the upstream edge sensor 110a and the downstream edge sensor 111a, and the like.
The image forming processing control part 212 controls the processing related to the image forming. The control object of the image forming processing control part 212 includes the main motor drive control circuit 361, the power circuit 362, the delivery roll drive control circuit 367, and primary transfer units 341 to 344.
(Description of Procedures of Paper Length Calculation by the Controller)
Then, an example of a control behavior of the controller 200 will be described with reference to a flowchart in
When forming the images on both sides of the paper 150, the paper is reversed in the reversing device 330 in
The controller 200 determines whether the sensor signal of the downstream edge sensor 111a is ON (step S1). When the sensor signal of the downstream edge sensor 111a is ON (step S1/YES), the controller 200 goes to the step S2. When the sensor signal of the downstream edge sensor 111a is not ON(step S1/NO), it repeats the procedure of the step S1. When the sensor signal of the downstream edge sensor ilia is ON, it means that the leading end of the paper arrives at the detection position of the downstream edge sensor 111a.
When the downstream edge sensor 111a detects the paper 150 (step S1/YES), the controller 200 starts the measurement of the timer t1 (step S2). The controller 200 starts the measurement of the pulse signal p2 output from the rotary encoder 103a according to the start of the measurement of the timer t1 (step S3). When the controller 200 detects the change of the signal level of the pulse signal p2 (step 54), it ends the measurement of the timer 1 (step S5). At this time, the controller 200 acquires the counting value of the timer t1 as a measurement parameter t1, and stores it in the RAM 203.
Then, the controller 200 starts the measurement of the timer t3 from t 0 (step S6), and determines whether the sensor signal output from the upstream edge sensor 110a is OFF, which means whether the paper 150 passes the detection position of the upstream edge sensor 110a (step S7). When the sensor signal of the upstream edge sensor 110a is OFF (step S7/YES), the controller 200 ends the measurement of the pulse signal p2 (step S10). In addition, the controller 200 also ends the measurement of the timer t3 (step S11). At this time, the controller 200 acquires the counting value of the timer t3 as a measurement parameter t3, and stores it in the RAM 203.
Meanwhile, when the sensor signal from the upstream edge sensor 110a is not OFF in the step S7 (step S7/NO), the controller 200 determines whether the change of the signal level of the pulse signal p2 exists (step S8). When the controller 200 detects the change of the signal level of the pulse signal p2 (step S8/YES), the controller 200 resets the timer t3 (step S9), goes back to the step S7, and restarts the measurement of the timer t3. When the controller 200 does not detect the change of the signal level of the pulse signal p2 (step S8/NO), the controller 200 repeats the step S7 again.
The controller 200 calculates a paper length L after the step 511 (step S12). The controller 200 calculates the paper length L by adding up paper lengths from L1 to L4 described later. The controller 200 adjusts the forming position of the image formed on the second side of the paper on the basis of the calculated paper length L (step 513).
Here, paper lengths L1 through L4 will be described with reference to
The paper length L2 will be described first. The paper length L2 is a paper length calculated based on the counted number of the pulse signal p2 output from the rotary encoder 103a during the period when both the upstream edge sensor 110a and the downstream edge sensor 111a detect the paper 150 (hereinafter, called measurement period). The measurement start timing of the measurement period is when the sensor signal of the downstream edge sensor 111a becomes ON as the leading end of the paper 150 arrives at the detection position of the downstream edge sensor 111a (See
The paper length L4 is a distance between the upstream edge sensor 110a and the downstream edge sensor 111a. As described above, the measurement of the paper length by the rotary encoder 103a is started after the leading end of the paper 150 arrives at the detection position. In addition, the measurement of the paper length by the rotary encoder 103a is not made after the posterior end of the paper 150 is pulled away from the detection position of the upstream edge sensor 110a. Therefore, it is necessary to add the distance from the measuring position of the rotary encoder 103a to the downstream edge sensor 111a before the measurement by the rotary encoder 103a, and the distance from the upstream edge sensor 110a to the measuring position of the rotary encoder 103a after the measurement by the rotary encoder 103a.
The paper length L1 and the paper length L3 are values to correct the error of measurement by the rotary encoder 103a. This error of measurement will be described with reference to
As illustrated in
In the same way, it takes time from when the sensor signal of this sensor 110a becomes OFF as the posterior end of the paper 150 is pulled away from the detection position of the upstream edge sensor 110a till when the signal level of the pulse signal p2 output from the rotary encoder 103a changes. The time from when the sensor signal of the upstream edge sensor 110a becomes OFF till when the signal level of the pulse signal p2 of a rotary encoder 103 changes is the measurement value of the timer t3 described above. The controller 200 calculates the paper length L3 based on the measurement value of the timer t3.
The controller 200 calculates the paper length L2 based on the counted number of the pulse signal p2 output from the rotary encoder 103 during the measurement period. In addition, the controller 200 calculates the paper length L1 by multiplying the measurement value of the timer t1 by the setting value V which is the delivery speed of the paper 150. In the same manner, the controller 200 calculates the paper length L3 by multiplying the measurement value of the timer t3 by the setting value V which is the delivery speed of the paper 150. Then, the controller 200 adds the value of the distance between the upstream edge sensor 110a and the downstream edge sensor 111a, which is stored in the RAM 203, to the value calculated by adding up calculated paper lengths L1, L2, and L3. A method to calculate the paper length L by adding up paper lengths from L1 to L4 is illustrated in
(Description of a Detail Composition of the Length Measuring Device)
In the length measuring device 100a in accordance with this exemplary embodiment, as illustrated in
As illustrated in
The paper 150 that passes the downstream edge sensor 111b is delivered on the delivery path by the upstream delivery roll 120b, and drawn into the downstream delivery roll 130b (See
When the delivery speed of the paper 150 becomes unsteady, the rotation of the length measuring roll 101b does not follow the delivery of the paper 150, and the length of the paper 150 can not be measured accurately.
As illustrated in
Output timings of sensor signals of the upstream edge sensor 110b and the downstream edge sensor 111b in the length measuring device 100b in
As described above, in the length measuring device 100b of a related art, the downstream delivery roll 130b is located on the more downstream side than the downstream edge sensor 111b. Therefore, after the sensor signal becomes ON at the timing c illustrated in
In the same manner, in the length measuring device 100b of the related art, the upstream delivery roll 120b is located on the more upstream side than the upstream edge sensor 110b. Therefore, after the posterior end of the paper 150 gets out of the upstream delivery roll 120b at the timing e illustrated in
Therefore, the paper 150 is drawn into the downstream delivery roll 130b and gets out of the upstream delivery roll 120b while the rotary encoder 103b is measuring the paper length, so that the delivery speed of the paper 150 becomes unsteady.
In this exemplary embodiment, as illustrated in
Output timings of sensor signals of the upstream edge sensor 110a and the downstream edge sensor 111a in the length measuring device 100a of this exemplary embodiment, and an output timing of the pulse signal that the rotary encoder 103a outputs are illustrated in
As described above, in the length measuring device 100a of this exemplary embodiment, the downstream delivery roll 130a is located on the more upstream side than the downstream edge sensor 111a. Accordingly, the paper 150 arrives at the detection position of the downstream edge sensor 111a after passing the downstream delivery roll 130a. Therefore, after the paper 150 is drawn into the downstream delivery roll 130a at the timing u illustrated in
In addition, in the length measuring device 100a of this exemplary embodiment, the upstream delivery roll 120a is located on the more downstream side than the upstream edge sensor 110a. Accordingly, the posterior end of the paper 150 gets out of the upstream delivery roll 120a after being pulled away from the detection position of the upstream edge sensor 110a. Therefore, after the sensor signal of the upstream edge sensor 110a becomes OFF at the timing w illustrated in
As described above, according to the length measuring device 100a of this exemplary embodiment, the paper 150 is not drawn into the downstream delivery roll 130a, or does not get out of the upstream delivery roll 120a, during the length measurement.
To measure the paper length with the length measuring roll 101 with high accuracy, it is preferable that a paper-slack does not exist in the paper 150 of which the length is being measured by the rotary encoder 103a. However, if the delivery speed of the upstream delivery roll 120a is faster than the delivery speed of the downstream delivery roll 130a, the paper-slack may occur in the paper 150 between the upstream delivery roll 120a and the downstream delivery roll 130a. If the paper-slack exists in the paper 150 between the upstream delivery roll 120a and the downstream delivery roll 130a, the measurement accuracy of the rotary encoder 103 with the length measuring roll 101a will be reduced.
Thus, the rotation speed is set to be equal to or slightly faster than the rotation speed of the upstream delivery roll 120a. Normally, even though the rotation speed of the upstream delivery roll 120a is adjusted to be equal to the rotation speed of the downstream delivery roll 130a, their rotation speeds frequently do not become equal because of a dimension tolerance of the delivery roll. Therefore, the rotation speed of the downstream delivery roll 130a is adjusted to be faster than the rotation speed of the upstream delivery roll 120a with the dimension tolerance being taken into account. Because of this adjustment, the paper-slack that occurs in the paper 150 of which the length is being measured by the rotary encoder 103 will be reduced.
In addition, when the rotation speed of the downstream delivery roll 130a is faster than the rotation speed of the upstream delivery roll 120a, the paper 150 may be tensioned as the downstream delivery roll 130a may draw the paper 150. This will not be a problem if the tension is proper, but the paper 150 will be stressed if the tension is too much. Then, to reduce the stress on the paper 150, one of the delivery forces of the upstream delivery roll 120a and the downstream delivery roll 130a is set to be weaker than the delivery force of the other delivery roll. Because of this setting, a slip occurs between the delivery roll (120a or 130a), of which the delivery force is weaker than the other, and the paper 150. The delivery force of the delivery roll is defined by the product of the friction factor of the roll μ and the nip pressure of the roll N.
In addition, a one-way clutch can be located in the drive system of the upstream delivery roll 120a to reduce the stress on the paper 150.
An example of a configuration using a one-way clutch as a drive system of the upstream delivery roll 120a is illustrated in
The one-way clutch 500 is installed in the gear 520. A roll shaft 125a of the delivery roll 122a is embedded at the center of the one-way clutch 500. When the gear 520 rotates by the drive power of a motor 510, the one-way clutch 500 rotates, and rotates the roll shaft 125a of the delivery roll 122a (See
When the paper is drawn into the downstream delivery roll 130a by the downstream delivery roll 130a rotating at high speed, the paper drives the roll shaft 125a of the upstream delivery roll 120a, and the roll shaft 125a tends to rotate faster than the gear 520 being rotated by the drive power of the motor 510. This condition will be described in
A second exemplary embodiment of the present invention will be described with reference to
A second upstream delivery roll 160c is located upstream of an upstream edge sensor 110c in a length measuring device 100c of the present invention. In addition, in the same manner as the first exemplary embodiment, a first upstream delivery roll 120c (corresponding to the upstream delivery roll 120a in the first exemplary embodiment) is located between the upstream edge sensor 110c and a length measuring roll 101c.
Furthermore, a second downstream delivery roll 170c is located downstream of a downstream edge sensor 111c. In the same manner as the first exemplary embodiment, a first downstream delivery roll 130c (corresponding to the downstream delivery roll 130a in the first exemplary embodiment) is located between the length measuring roll 101c and the downstream edge sensor 111c.
In this exemplary embodiment, the delivery force of the first upstream delivery roll 120e is set to be equal to or stronger than the delivery force of the second upstream delivery roll 160e. In the same manner, the delivery force of the first downstream delivery roll 130c is set to be equal to or stronger than the delivery force of the second downstream delivery roll 170c.
When the delivery force of the second upstream delivery roll 160c is stronger than the delivery force of the first upstream delivery roll 120c, the influence that the posterior end of the paper 150 gets out of the second upstream delivery roll 160c (such as speed fluctuation) propagates to the paper 150 of which the length is being measured by the length measuring roll 101c. This is caused because the delivery force of the first upstream delivery roll 120c is weaker than the delivery force of the second upstream delivery roll 160c. Therefore, in this exemplary embodiment, the delivery force of the first upstream delivery roll 120c is set to be equal to or stronger than the delivery force of the second upstream delivery roll 160c.
In the same manner, the delivery force of the second downstream delivery roll 170c is stronger than the delivery force of the first downstream delivery roll 130e, the influence that the leading end of the paper 150 is drawn into the second downstream delivery roll 170c (a speed fluctuation) is propagated to the paper 150 of which the length is being measured by the length measuring roll 101c. This is caused because the delivery force of the first downstream delivery roll 130c is weaker than the delivery force of the second downstream delivery roll 170c. Therefore, in this exemplary embodiment, the delivery force of the first downstream delivery roll 130c is set to be equal to or stronger than the delivery force of the second downstream delivery roll 170c.
According to this exemplary embodiment, when two delivery rolls are located upstream of the length measuring roll 101c, the delivery force of the first upstream delivery roll 120c located on the downstream side is set to be equal to or stronger than the delivery force of the second upstream delivery roll 160c located on the upstream side. Because of these settings, the change of the delivery force propagated to the paper 150 is reduced.
In the same manner, when two delivery rolls are located downstream of the length measuring roll 101c, the deliver force of the first downstream delivery roll 130c located on the upstream side is set to be equal to or stronger than the delivery force of the second downstream delivery roll 170c located on the downstream side. Because of these settings, the change of the delivery force propagated to the paper 150 is reduced.
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 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 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-151234 | Jun 2009 | JP | national |
