Patent Grant
11319177
This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2018-207106 filed on Nov. 2, 2018, the contents of which are hereby incorporated by reference.
The present disclosure relates to a sensor unit which is incorporated in image forming apparatuses such as facsimile machines, copiers, and printers and which includes a sensor for sensing the edge of a sheet. The present disclosure also relates to image forming apparatuses provided with such a sensor unit.
Image forming apparatuses such as facsimile machines, copiers, and printers are configured to record an image on a sheet such as paper, cloth, or an OHP sheet. These image forming apparatuses can be classified into an electrophotographic type, an ink-jet type, etc. based on their recording method.
During printing on a sheet using an image forming apparatus, if the sheet deviates in the direction (sheet width direction) perpendicular to the conveying direction, the printing position changes from one sheet to another. Thus, for example in a case where binding is performed after printing, high accuracy in the printing position on each page is required.
Thus, there are known image forming apparatuses provided with an edge detection sensor comprising a CIS (contact image sensor) or the like which is arranged opposite a sheet conveying passage and which detects the side edge along the sheet conveying direction of a sheet, a lighting device which is arranged on the same side as or on the opposite side from the edge detection sensor with respect to the sheet conveying passage and which emits light toward the sheet conveying passage, an upper guide member which constitutes the top face of the sheet conveying passage, and a lower guide member which constitutes the bottom face of the sheet conveying passage. This image forming apparatus senses the position of an end part of a sheet in its width direction based on the difference in the intensity of the light received by the edge detection sensor according to presence or absence of the sheet.
A conventional image forming apparatus is disclosed which is provided with an edge detection sensor for detecting the position of an end part of a sheet in the width direction and upper and lower guide members which constitute the top and the bottom faces, respectively, of the sheet conveying passage.
According to one aspect of what is disclosed herein, a sensor unit includes a sheet conveying passage through which a sheet is conveyed; a first housing which extends in the width direction perpendicular to the conveying direction of the sheet and which constitutes a first conveying face of the sheet conveying passage; a second housing which extends in the width direction and which constitutes a second conveying face of the sheet conveying passage arranged opposite the first conveying face with a predetermined gap; an edge detection sensor which is arranged in one of the first and second housings and which detects the side edge, along the conveying direction, of the sheet passing through the sheet conveying passage; and a gap adjuster which supports the first housing movably from a first position where the size of the gap equals a reference value in the direction in which the size of the gap increases from the reference value. When, with the first housing arranged at the first position, a sheet with a thickness greater than the reference value passes through the sheet conveying passage, the first housing moves in the direction in which the size of the gap increases as the sheet enters the sheet conveying passage, to allow passage of the sheet.
This and other objects of the present disclosure, and the specific benefits obtained according to the present disclosure, will become apparent from the description of embodiments which follows.
Hereinafter, with reference to the accompanying drawings, embodiments of the present disclosure will be described.
As shown in
Inside the printer 100, a first sheet conveying passage 4a is provided. The first sheet conveying passage 4a is located to the upper right of the sheet feeding cassette 2a, and to the left of the manual feed tray 2b. Sheets P fed out of the sheet feeding cassette 2a are conveyed vertically upward along a side face of the printer main body 1 via the first sheet conveying passage 4a, and sheets fed out of the manual feed tray 2b are conveyed to the left in a substantially horizontal direction via the first sheet conveying passage 4a.
At the downstream end of the first sheet conveying passage 4a in the sheet conveying direction, the sensor unit 30 for sensing the side edge (the position of an end part in the width direction (the direction perpendicular to the sheet conveying direction)) along the sheet conveying direction of sheets P is arranged. On the downstream side of the sensor unit 30, close to it, a first belt conveying portion 5 and a recording portion (an image forming portion) 9 are arranged.
In the sensor unit 30, a registration roller pair 13 is provided. The registration roller pair 13, while correcting skewed conveying of sheets P and coordinating with the timing of ink ejecting operation by the recording portion 9, feeds out the sheets P toward the first belt conveying portion 5. The structure of the sensor unit 30 will be described in detail later.
The first belt conveying portion 5 is provided with an endless first conveying belt 8 that is wound around a first driving roller 6 and a first driven roller 7. In the first conveying belt 8, a large number of vent holes (unillustrated) for sucking in air are provided. A sheet P fed out from the registration roller pair 13 is, while being held by suction on the first conveying belt 8 by a sheet suction portion 20 provided inside the first conveying belt 8, passes under the recording portion 9.
The recording portion 9 includes line heads 10C, 10M, 10Y and 10K. The line heads 10C to 10K record an image on a sheet P conveyed while being held by suction on the conveying face of the first conveying belt 8. To the line heads 10C to 10K, ink of four colors (cyan, magenta, yellow, and black) stored in ink tanks (unillustrated) is supplied such that ink of the different colors are supplied to corresponding ones of the line heads 10C to 10K respectively.
Toward a sheet P sucked on the first conveying belt 8, ink of the respective colors is sequentially ejected from the line heads 10C to 10K, and thereby a full-color image having ink of four colors, namely yellow, magenta, cyan, and black, overlaid together is recorded on the sheet P. The printer 100 can record also a monochrome image by using only black ink.
On the downstream side (left side in
On the downstream side of the second belt conveying portion 11 in the sheet conveying direction, near the left side face of the printer main body 1, a decurler portion 14 is provided. The sheet P with the ink dried at the second belt conveying portion 11 is conveyed to the decurler portion 14 so that the curled sheet P is straightened.
On the downstream side (in an upper part in
Under the second belt conveying portion 11, a maintenance unit 19 is arranged. The maintenance unit 19, when performing maintenance of the respective recording heads of the line heads 10C to 10K, moves to under the recording portion 9, where it wipes off the ink ejected (purged) from ejection nozzles in the recording heads and collects the wiped-off ink.
Next, the structure of the sensor unit 30 will be described in detail.
The sensor unit 30 is provided with the unit housing 31, the registration roller pair 13, a CIS carriage main body 37, and a carriage moving mechanism 50. The unit housing 31 supports the registration roller pair 13 so as to be rotatable as well as supports the CIS carriage main body 37 so as to be movable in the sheet width direction (in the arrow AA′ direction). In an upstream-side end part of the unit housing 31 in the sheet conveying direction (in the arrow B direction), there is provided a registration entrance guide 33 that guides sheets P to a nip portion of the registration roller pair 13.
As shown in
The CIS carriage main body 37 is arranged adjacent to a part (left-side in
The CIS 40, based on the light intensity difference between the part that is struck by the light from the lighting device 60 and the part that is intercepted by a sheet P, senses the side edge of a sheet P in its width direction. The structure of the lighting device 60 will be described in detail later.
The CIS carriage main body 37 includes a CIS housing portion 37a in which the CIS 40 is housed and shaft guide portions 37b in which the shafts 47 of the unit housing 31 are slidably inserted. The CIS housing portion 37a is provided substantially over the entire region of the CIS carriage main body 37 in its longitudinal direction. There are provided two shaft guide portions 37b at each end part of the CIS carriage main body 37 in its longitudinal direction, that is, two pairs of the shaft guide portions 37b in the sheet conveying direction.
As shown in
The CIS housing 48 has a bottom face portion 48a, a side face portion 48b which is erect from the peripheral edge of the bottom face portion 48a, and a supporting face portion 48c arranged at a predetermined distance from the bottom face portion 48a. The CIS substrate 45 is fixed on the bottom face portion 48a. The rod lenses in the rod lens array 46 are formed in a cylindrical shape and are arranged on the sheet conveying passage 12 side (on the upper side) with respect to the light receiving portion 43. The rod lens array 46 penetrates the supporting face portion 48c and is fixed to the supporting face portion 48c at a predetermined distance from the light receiving portion 43. The rod lens array 46 guides the light from the lighting device 60 to the light receiving portion 43.
Next, the structure of the lighting device 60 will be described in detail.
As shown in
The lighting housing 67 has a function as a sheet guide which forms a part of the sheet conveying passage 12 and a function as a light guide body holding member which supports the light guide body 64. The lighting housing 67 includes a stay 68 which protrudes in such a direction as to retract from the sheet conveying passage 12 (upward). The stay 68 extends in the sheet width direction and is, by being surrounded by a top face portion 68c and a pair of side face portions so as to open downward, formed in a shape with a substantially rectangular cross section. In the top face portion 68c of the stay 68, a slit 68d, in which a light guide portion 64a, described later, of the light guide body 64 is arranged, is formed so as to extend in the sheet width direction.
A contact glass 42b is fixed to the lighting housing 67 using clips or the like (unillustrated), and the bottom face of the contact glass 42b and the bottom face of the lighting housing 67 form the top face (first conveying face) 12a of the sheet conveying passage 12. The contact glass 42a is placed on the CIS carriage main body 37. The top face of the contact glass 42a and the top face of the CIS carriage main body 37 form the bottom face (second conveying face) 12b of the sheet conveying passage 12. The lighting housing 67 is one example of a “first housing” according to the present disclosure, and the CIS carriage main body 37 is one example of a “second housing” according to the present disclosure.
As shown in
As shown in
On the opposite face 64d, a reflection sheet 69a for reflecting the light exiting through the opposite face 64d to shine the light back into the guide body 64 is provided. On the rear face 64f, a plurality of concave prisms 64g are formed which are arrayed in the sheet width direction and which totally reflect the light entered through the light receiving face 64c toward the light exit face 64e.
As shown in
The light emitted from the LED 62 enters the light guide body 64 and is guided in the sheet width direction to exit toward the sheet conveying passage 12. The light is then diffused by the light diffusion plate 65 and is transmitted through the contact glasses 42b and 42a to be shone into the CIS 40. The light diffusion plate 65 is a transmission type light diffusion plate which transmits the light from the light guide body 64.
Owing to the provision of the light diffusion plate 65 for diffusing the light exited from the light guide body 64, even when the light exited from the light guide body 64 is uneven, it is possible to make the light even with the light diffusion plate 65. This makes it possible to reduce the increase, resulting from uneven light, of the difference in the intensity of the light received at the CIS 40.
As shown in
The pair of supporting portions 68e is formed so as to extend in the sheet width direction and is arranged so as to face each other across the light guide portion 64a, The supporting portions 68e have a function as a light shielding member which, when the LED light that has passed from the light guide portion 64a into the flange portion 64b or the external disturbance light that has passed from the rear face 64f into the flange portion 64b exits through the supported face 64h of the flange portion 64b to the CIS 40, shields the light.
As shown in
As shown in
As shown in
Here, according to this embodiment, the lighting housing 67 is structured to be movable in such a direction (here, the up-down direction) as to move closer to and away from the CIS carriage main body 37. That is, the sensor unit 30 is structured such that the gap of the sheet conveying passage 12 changes as the lighting housing 67 moves up and down. When the lighting housing 67 moves up and down, the contact glass 42b, the lighting device 60, and the like also move up and down together with the lighting housing 67.
The lighting housing 67 is structured so as to be movable between the initial position (position in
Specifically, as shown in
To the abutted portion 37d, a regulation plate 90 made of sheet metal is fixed. The regulation plate 90 has a fixed portion 91 which is fixed to the outer face of the abutted portion 37d using screws 95 and which extends upward, a bent portion 92 which extends inward in the sheet width direction from the tip end (top end) of the fixed portion 91 and which faces the top face of the abutted portion 37d, and a bent piece 93 which extends downward from the inner end (left end in
In a regular state, the bottom face of the abutting portion 67b abuts on the top face of the abutted portion 37d under the own weight of the lighting housing 67 and the like and under the biasing force of the biasing member 97. In this state, the gap of the sheet conveying passage 12 is the smallest, and the lighting housing 67 is arranged at the initial position (positions in
When, with the lighting housing 67 arranged at the initial position, for example, a sheet of cardboard with a thickness greater than the size of the gap (reference value) of the sheet conveying passage 12 passes through the sheet conveying passage 12, the cardboard makes contact with the bottom face of the lighting housing 67 (or the contact glass 42b) to push up the lighting housing 67, the contact glass 42b, and the like. This widens the gap of the sheet conveying passage 12. As shown in
In this way, the biasing member 97, the regulation plate 90, the guide shaft 37c, the abutted portion 37d, the abutting portion 67b, and the like constitute a gap adjuster 99 which supports the lighting housing 67 movably between the initial position and the fully expanded position.
In this embodiment, as shown in
The CIS control circuit 71, according to the settings made by the CPU 70, sends to the CIS 40 a reference clock signal for reading a signal from the CIS 40 and an accumulation time determination signal for determining the electric charge accumulation time in the CIS 40. The CIS control circuit 71 sends a PWM signal to an LED driving circuit 73 for setting the value of a current to pass in the LED 62. The LED driving circuit 73 generates a direct-current voltage in accordance with the PWM signal from the CIS control circuit 71 and makes it a reference voltage of the current to pass in the LED 62. The CIS control circuit 71 generates a comparison reference voltage (threshold voltage) for binarizing in a binarization circuit 75 an analogue signal (output signal) from the CIS 40.
At the timing when a sheet P in a standby state at the registration roller pair 13 (see
In response to the next accumulation time determination signal and reference clock signal, the CIS 40 outputs a voltage equivalent to the quantity of light accumulated while the LED 62 is on in each pixel (photoelectric conversion element) in a pixel group of the light receiving portion 43 one pixel at a time as an output signal. The output signal output from the CIS 40 is binarized in the binarization circuit 75 by being compared with the comparison reference voltage (threshold voltage) and is input to the CIS control circuit 71 as a digital signal.
The CIS control circuit 71, for each output signal output by the CIS 40, checks whether the value of the digital signal binarized in the binarization circuit 75 is 0 or 1 sequentially one pixel at a time. Then, the CIS control circuit 71 senses the position (position of the photoelectric conversion element) of the pixel in the light receiving portion 43 where the value of the digital signal changes from 0 to 1 or from 1 to 0.
When the CIS control circuit 71 senses the position of the pixel where the value of the digital signal has changed, the position of the changed pixel is determined to be the edge position of a sheet P in its width direction. The CPU 70 calculates the amount of deviation between the edge position determined by the CIS control circuit 71 and the edge position (reference edge position) when a sheet P is conveyed at an ideal conveying position (reference conveying position) where the sheet P passes along the center position of the sheet-passing region. The calculated deviation amount is transmitted to a nozzle shift control portion 77, The nozzle shift control portion 77, according to the transmitted deviation amount of a sheet P in its width direction, shifts the use region of ink ejecting nozzles of the line heads 10C to 10K in the recording portion 9. The nozzle shift control portion 77 is one example of “control portion” according to the present disclosure.
In this embodiment, as described above, when, with the lighting housing 67 arranged at the initial position, a sheet P (cardboard etc.) with a thickness greater than the size (reference value) of the gap of the sheet conveying passage 12 passes through the sheet conveying passage 12, the lighting housing 67 moves in a direction away from the CIS carriage main body 37 as the sheet P enters the sheet conveying passage 12, to allow the passage of the sheet P. This helps widen the gap when a sheet P thicker than the size of the gap of the sheet conveying passage 12 passes through the sheet conveying passage 12 to prevent the conveyance resistance from becoming too high. Thus, it is possible to suppress conveyance failure.
The lighting housing 67 is movable from the initial position in a direction in which the size of the gap increases from the reference value, and thus it is possible to prevent the gap of the sheet conveying passage 12 with the lighting housing 67 arranged at the initial position from becoming too large. In other words, there is no need to set the gap of the sheet conveying passage 12 at the maximum thickness (for example, 2 to 3 mm) of sheets. Thus, even when a thin sheet P such as regular paper is conveyed along the top face 12a or the bottom face 12b with the lighting housing 67 arranged at the initial position, it is possible to prevent the CIS 40 from losing focus on the sheet P. Thus, it is possible to prevent the sensing accuracy of the side edge of the sheet P from lowering.
As described above, the focal position F of the CIS 40 with the lighting housing 67 arranged at the initial position is set at the center L12 of the gap of the sheet conveying passage 12. This makes it possible to set the initial position of the lighting housing 67 such that the size of the gap of the sheet conveying passage 12 is about the same as the focal range of the CIS 40. This helps increase the gap of the sheet conveying passage 12 with the lighting housing 67 arranged at the initial position, and thus it is possible to further prevent the conveyance resistance for conveying the sheet P from becoming too high.
As described above, the CIS 40 is held by the CIS carriage main body 37. Thus, unlike in a case where the CIS 40 is held by the lighting housing 67, there is no need to move (push up) the CIS 40 to widen the gap of the sheet conveying passage 12 (of the lighting housing 67 and the CIS 40, only the lighting housing 67 needs to be pushed up), and thus it is possible to further prevent the conveyance resistance from becoming too high.
As described above, the biasing member 97 is a compression spring arranged between the bent portion 92 and the abutting portion 67b. This makes it possible to easily adjust the load when the CIS 40 is pushed up.
As described above, on the CIS carriage main body 37, a guide shaft 37c which extends along the moving direction of the lighting housing 67 is provided. In the abutting portion 67b, the guide hole 67a for inserting the guide shaft 37c is provided. This makes it possible to easily move the lighting housing 67 in the thickness direction of the sheet conveying passage 12.
As described above, the lighting device 60 is provided which is arranged on the side opposite from the CIS 40 with respect to the sheet conveying passage 12 and which emits light toward the CIS 40. This makes it possible to sense the side edge of the sheet P in the width direction based on the difference in the intensity of the light received by the CIS 40 according to the presence or absence of the sheet P, and thus, regardless of the color of the sheet P, it is possible to reliably sense the side edge of the sheet P in the width direction. When the lighting device 60 is arranged on the same side as the CIS 40 with respect to the sheet conveying passage 12, it may not be possible to sense the side edge in the width direction depending on the color of the sheet P. Specifically, when, for example, the sheet P is white and the area outside the sheet P (non-sheet P passage area) is black, the intensity difference between the light reflected from the sheet P and the light reflected from the non-passage area is large, and thus, the side edge of the sheet P in the width direction is sensed by the CIS 40. On the other hand, when, for example, the sheet P is black and the non-passage area is also black, the intensity difference between the light reflected from the sheet P and the light reflected from the non-sheet P passage area is small, and thus, the side edge of the sheet P in the width direction cannot be sensed by the CIS 40.
As described above, based on the edge position of the sheet P sensed by the sensor unit 30, the position of the image on the sheet P is corrected. This makes it possible to easily prevent the deviation of the image position with respect to the sheet P, and thus, degradation of the image quality can be easily prevented.
The embodiment described above is in no way meant to limit the present disclosure, which thus allows for many modifications and variations within the spirit of the present disclosure. For example, although the above embodiment deals with an example where the CIS 40 is used as a sensor for sensing the side edge of a sheet P, any sensor other than a CIS, such as a CCD, may be used.
Although the embodiment described above deals with, as an example, a printer 100 of an ink-jet recording type which ejects ink onto a sheet P from ink ejection nozzles of line heads 10C to 10K to record an image, the present disclosure is not limited to printers 100 of an ink-jet recording type. Instead, the present disclosure may be applied, for example, to image forming apparatuses of an electrophotographic type which emits a laser beam onto an image carrier such as a photosensitive drum to form an electrostatic latent image, attach toner to the electrostatic latent image to form a toner image, transfer the toner image onto a sheet, and apply heat and pressure to the transferred unfixed toner to form a permanent image.
Although the above embodiments deal with an example where the CIS 40 is held by the CIS carriage main body 37 (second housing), this is in no way meant to limit the present disclosure. Instead, the CIS 40 may be held by the lighting housing 67 (first housing). That is, the CIS 40 may move together with the first housing.
Although the above embodiments deal with an example where the lighting housing 67 (first housing) arranged over the sheet conveying passage 12 moves in the up-down direction, this is in no way meant to limit the present disclosure. Instead, the CIS carriage main body 37 arranged under the sheet conveying passage 12 may move in the up-down direction. In this case, the CIS carriage main body 37 corresponds to the “first housing” of the present disclosure, and the lighting housing 67 corresponds to the “second housing” of the present disclosure.
Although the above embodiments deal with an example where the lighting device 60 is arranged on the side opposite from the CIS 40 with respect to the sheet conveying passage 12, this is in no way meant to limit the present disclosure. The lighting device 60 may be arranged on the same side as the CIS 40 with respect to the sheet conveying passage 12 to read the reflected light reflected by the sheet P by the CIS 40.
Although the above embodiments deal with an example where the light guide body 64 is provided which shines light perpendicularly with respect to the sheet conveying passage 12, this is in no way meant to limit the present disclosure. Instead, the light guide body 64 does not necessarily be provided. In this case, as in the sensor unit 30 shown in
Any configurations achieved by combining the configurations of the embodiments and modified examples described above are also within the technical scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2018-207106 | Nov 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 9674389 | Kanaya | Jun 2017 | B2 |
| 9802776 | Fukusaka | Oct 2017 | B2 |
| 11008188 | Morikawa | May 2021 | B2 |
| 11225090 | Osawa | Jan 2022 | B2 |
| 20060072950 | Lim et al. | Apr 2006 | A1 |
| 20190063901 | Mitsui | Feb 2019 | A1 |
| 20200198910 | Takato | Jun 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 1755532 | Apr 2006 | CN |
| 201062173 | May 2008 | CN |
| 206552930 | Oct 2017 | CN |
| 2011-176669 | Sep 2011 | JP |
| WO-2018105325 | Jun 2018 | WO |
| Entry |
|---|
| Chinese Office Action dated Jan. 27, 2021, issued by the China National Intellectual Property Administration in corresponding application CN 201911016120.X. |
| Chinese Office Action dated Oct. 15, 2021, issued by the China National Intellectual Property Administration in corresponding application CN 201911016120.X. |
| Number | Date | Country | |
|---|---|---|---|
| 20200140216 A1 | May 2020 | US |
