JPH11209008A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a printer and to reduce the cost of the printer with a shortened turn-over time of medium. SOLUTION: A printer comprises a medium storage means; a hopping roller 32 rotated by a driving means to feed mediums out of the medium storage means; a printing means operative to perform printing on the medium fed by the hopping roller 32; a discharge roller 35 operative to discharge the printed mediums; a stacker 31 positioned above the medium storage means and operative to stack the delivered mediums; a medium-guiding means mounted aslope and operative to guide the mediums discharged by the discharge roller 35 to the hopping roller 32; and a switching means provided so as to switch freely and operative to selectively send the mediums discharged by the delivery roller 35 to either the stacker 31 or the medium-guiding means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a printing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a printing apparatus capable of printing on both sides of a sheet as a medium, a sheet on which printing is performed on one side is inverted and printing is performed on the other side. It has become. FIG. 2 is a schematic side view of a conventional printing apparatus.

In the figure, 11 is a paper cassette, 12 is a hopping roller, 13 is a paper feed roller, 14 is a photosensitive drum, 15 is a laser light source, 16 is a developing roller, 17 is a fixing device, and 18 is a first switching gate. , 19 are second switching gates, 20 is a reversing roller, 21 and 22 are transport rollers, 23
Denotes a discharge roller, and 24 denotes a discharge tray. Next, the operation of the printing apparatus having the above configuration will be described.

First, the operation at the time of single-sided printing will be described. After the surface of the photosensitive drum 14 is uniformly and uniformly charged, the photosensitive drum 14 is exposed by a laser light source 15 to form an electrostatic latent image. Next, the electrostatic latent image is developed into a toner image by a developing roller 16, and the toner image is transferred to a sheet (not shown) by a transfer roller (not shown) and fixed by a fixing device 17.

On the other hand, the sheets stored in the sheet cassette 11 are fed one by one by a hopping roller 12 and sent to a transfer section between a photosensitive drum 14 and a transfer roller by a feed roller 13. In the case of single-sided printing, the sheet is conveyed along the main conveyance path P1, is sent upward by the first switching gate 18, passes through the conveyance path P2, and is discharged to the discharge tray 24 by the discharge rollers 23.

In the case of double-sided printing, the paper after printing on one side is conveyed along the main conveying path P1.
First and second switching gates 18 and 19 and reversing roller 20
And then stopped before passing completely through the reversing roller 20. Next, the second switching gate 1
9 is switched and the reversing roller 20 is rotated in the reverse direction, the sheet is conveyed along the sub-conveying path P3 by the conveying rollers 21 and 22, and is reversed at the curved portion q of the sub-conveying path P3. Then, the sheet is again fed to the transfer section by the sheet feeding roller 13. Next, the toner image is transferred to the sheet by the transfer roller and fixed by the fixing device 17. In this way, the sheet on which the other surface has been printed is conveyed along the main conveyance path P <b> 1, sent upward by the first switching gate 18, and discharged to the discharge tray 24 by the discharge roller 23. .

[0007]

However, in the above-mentioned conventional printing apparatus, it is necessary to form a sub-transport path P3 in parallel with the main transport path P1 in order to reverse the sheet. Therefore, the printing device not only becomes large, but also
The cost increases. Further, since it is necessary to convey the sheet along the sub-conveying path P3, the time required to reverse the sheet becomes longer.

[0008] The present invention solves the problems of the conventional printing apparatus, and can reduce the size, reduce the cost, and shorten the time for reversing the medium. It is intended to provide a device.

[0009]

For this purpose, in a printing apparatus according to the present invention, a medium storing means for storing a medium and a driving means are rotated to rotate the medium in the medium storing means with the rotation. A hopping roller to feed out,
A printing unit that prints on the medium fed by the hopping roller, a discharge roller that discharges the medium after the printing is performed, and a printing unit that is disposed above the medium housing unit and is discharged by the discharge roller. A stacker for stacking the medium, and a medium guide means disposed to be inclined and for guiding the medium discharged by the discharge roller to a hopping roller, and switchably disposed and discharged by the discharge roller. Switching means for selectively sending a medium to the stacker and the medium guiding means.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of a printing apparatus according to the first embodiment of the present invention, and FIG. 3 is a perspective view of the printing apparatus according to the first embodiment of the present invention. In the figure, reference numeral 11 denotes a paper cassette which is formed at an upper portion on the back side of the main body 10 of the printing apparatus so as to be inclined with respect to the main body 10 and serves as medium storage means for storing paper 27 as a medium. A paper presser 25 is provided below the paper cassette 11, and a hopping roller 32 is rotatably provided facing the paper presser 25. The paper presser 25 is swingably supported by a pin 25a, and is urged by a spring 26 to press a paper 27 against a hopping roller 32. Also,
A claw 28 is provided on the upper end of the front wall 11a of the paper cassette 11, and the claw 28 presses the front end of the paper 27.

The hopping roller 32 has a surface formed of a rubber material to increase the coefficient of friction. The hopping roller 32 is rotated by driving means (not shown) to feed out the sheets 27 one by one. Further, a paper feed roller 13 is provided adjacent to the hopping roller 32, and the paper feed roller 13 is
The paper 27 fed by the hopping roller 32 is fed along a “U” -shaped transport path P11 and sent to the cylindrical photosensitive drum. Around the photosensitive drum 14, a charging roller 53, a cleaning roller 54, an LED
The head 29, the developing roller 16, the transfer roller 56, and the like are provided. Reference numeral 17 denotes a fixing device including a heating roller 17a and a pressure roller 17b, and a heater (not shown) is provided in the heating roller 17a.

The surface of the photosensitive drum 14 is
After being uniformly and uniformly charged by the charging roller 53, it is exposed by the LED head 29 to form an electrostatic latent image. Next, the electrostatic latent image is developed into a toner image by the developing roller 16, and the toner image is transferred to the sheet 27 by the transfer roller 56. The sheet 27 to which the toner image has been transferred is conveyed along a conveyance path P12 formed in parallel with the sheet cassette 11 and sent to the fixing device 17, where the toner image is fixed on the sheet 27. . The exposure is performed according to print data transmitted from a host computer (not shown). The photosensitive drum 14, the developing roller 16, the LED head 2
9, the charging roller 53, the cleaning roller 54, the transfer roller 56, and the fixing device 17 constitute a printing unit.

A discharge roller 35 is disposed adjacent to the fixing device 17, and the sheet 27 after the fixing is carried out.
The sheet is selectively discharged to a stacker 31 and a reversing paper feed guide 36 as a medium guiding unit by a discharge roller 35. For this purpose, the stacker 31 is
And the stacker 31 and the paper cassette 1
1, a paper feed guide 36 is formed to be inclined from below the stacker 31 toward the hopping roller 32 and the front end of the paper cassette 11. The discharge roller 3
A switching gate 30 as switching means is provided between the stacker 5 and the stacker 31. The switching gate 30 includes a stacker 31
It is disposed so as to be swingable about a hinge 30a provided at the end on the side of the transport path P12, and a claw 30b is formed at the end on the side of the transport path P12. The switching gate 30 is switched by an electromagnetic magnet (not shown) to take an upper position and a lower position.
6, when the paper 27 is placed in the lower position,
Selectively send to.

Reference numeral 33 denotes a paper feed sensor for detecting whether or not the paper 27 has been correctly fed, and reference numeral 34 denotes a discharge sensor for detecting whether or not the paper 27 has been correctly discharged. The timing of exposure to the photosensitive drum 14 is determined based on the detection result of the sensor 33. Next, the operation of the printing apparatus when performing one-sided printing will be described.

FIG. 4 is a first diagram showing a sheet feeding state during single-sided printing according to the first embodiment of the present invention, and FIG. 5 is a sheet feeding state during single-sided printing according to the first embodiment of the present invention. FIG. 6 is a third diagram showing a sheet feeding state during single-sided printing according to the first embodiment of the present invention, and FIG. 7 is a diagram illustrating a sheet feeding state according to the first embodiment of the present invention. It is a figure showing the discharge state of.

In this case, one sheet of paper 27 stored in the paper cassette 11 (FIG. 1) is fed by one rotation of the hopping roller 32. The hopping roller 32 is formed with a notch 32c over a predetermined range in the circumferential direction. The notch 3
2c is a first surface S1 extending radially inward from a predetermined position in the circumferential direction, a second surface S2 extending circumferentially from an end of the first surface S1, and the second surface. A third surface S3 extending obliquely outward from the end of S2 is formed by the outer peripheral surface of the hopping roller 32 and the first surface S1.
A second protrusion 32b is formed by the outer peripheral surface of the hopping roller 32 and the third surface S3. Then, as shown in FIG. 4, normally, the first protruding portion 32a is located at the lowest position, and the hopping roller 32 and the sheet 27 are not brought into contact with each other. Also,
At the time of paper feeding, as shown in FIGS. 5 and 6, when the hopping roller 32 is rotated in the direction of the arrow, the second protruding portion 32b frictionally urges the uppermost sheet 27 in the sheet cassette 11 in the drawing. Send to the left. In this way, the sheet 27 is fed by the hopping roller 32.

When the paper feed sensor 33 detects that the paper 27 has been correctly fed, and confirms the transport timing of the paper 27, the paper 27 is transferred to the photosensitive drum 14.
Is transferred to a transfer section between the transfer roller 56 and the transfer roller 56. At this time, a toner image is formed on the photosensitive drum 14, and the toner image is transferred to the sheet 27 by the transfer roller 56. The sheet 27 to which the toner image has been transferred is conveyed along the conveyance path P12 and sent to the fixing device 17, where the toner image is fixed on the sheet 27. In this manner, printing is performed on one side of the paper 27. Subsequently, the paper 27 is conveyed by rotating the discharge roller 35 in the direction of the arrow, and is discharged to the stacker 31. At this time, the switching gate 30 is located at the lower position as shown in FIG. Reference numeral 11a denotes a front wall of the paper cassette 11, reference numeral 13 denotes a paper feed roller, reference numeral 25 denotes a paper presser, reference numeral 26 denotes a spring, and reference numeral 28 denotes a claw disposed at an upper end of the front wall 11a.

Next, the operation of the printing apparatus when performing double-sided printing will be described. The operation from the feeding of the sheet 27 stored in the sheet cassette 11 by the hopping roller 32 to the fixing of the toner image on the sheet 27 by the fixing device 17 is the same as the case of performing one-sided printing. The description is omitted. FIG. 8 is a first diagram illustrating a state of refeeding during double-sided printing according to the first embodiment of the present invention, and FIG. 9 is a diagram illustrating a state of refeeding during double-sided printing according to the first embodiment of the present invention. It is the 2nd figure shown.

First, as shown in FIG. 8, the switching gate 30 is placed at the upper position, and the paper 27 already printed on one side and conveyed by the discharge roller 35 in the direction of the arrow is displayed.
Are transported under the switching gate 30 and are fed by the paper feed guide 36.
Is discharged. Then, as shown in FIG.
The sheet 7 is discharged by the discharge roller 35, and when the rear end 27a of the sheet 27 is completely separated from the discharge roller 35, the sheet 27 slides on the paper feed guide 36 by gravity and moves downward.
Are the hopping roller 32 and the paper cassette 11 (FIG. 1).
When the sheet enters the hopping roller 32, that is, the first surface S1, through the notch 32c (FIG. 4), and is stopped.

Subsequently, when the hopping roller 32 is rotated again, the second protrusion 32b feeds the sheet 27 to the left side in the figure by friction. In this way, the sheet 27 is fed by the hopping roller 32. Then, the paper feed sensor 33 detects that the paper 27 has been correctly fed, and when the conveyance timing of the paper 27 is confirmed, the paper 27 is sent to the transfer unit. At this time, a toner image is formed on the photosensitive drum 14, and the toner image is transferred to the other surface of the sheet 27 by the transfer roller 56. The sheet 27 to which the toner image has been transferred is transported on the transport path P
The toner image is conveyed along the sheet 12 and sent to the fixing device 17, and the toner image is fixed on the sheet 27 by the fixing device 17. In this way, printing is performed on the other side of the sheet 27. Subsequently, the paper 27 is conveyed by a discharge roller 35 and discharged to the stacker 31. At this time, as shown in FIG. 7, the switching gate 30 is placed at the lower position.

When printing is performed on the other side of the sheet 27, the rear end 27a of the sheet 27 becomes the front end and the transport path P
11, and transported along P12. Therefore, the image data for printing on the other side of the paper 27 is inverted upside down from the image data for printing on one side. That is, printing is performed from the lower side of the sheet 27 to the upper side.

As described above, in the present embodiment, the paper feed guide 3 is provided between the stacker 31 and the paper cassette 11.
Since the sheet 6 is formed, it is not necessary to additionally form a transport path to reverse the sheet 27. Therefore, not only the size of the printing apparatus can be reduced, but also the cost of the printing apparatus can be reduced. In addition, since the reversal of the paper 27 can be completed only by discharging the paper 27 to the paper feed guide 36 and placing the rear end 27a between the hopping roller 32 and the front end of the paper cassette 11, the paper 27 can be reversed. It is possible to shorten the time required for the operation.

Since the notch 32c is formed in the hopping roller 32, the rear end 27a of the sheet 27 can sufficiently enter between the hopping roller 32 and the front end of the sheet cassette 11. Therefore, it is possible to prevent the occurrence of double running when the sheet 27 is fed out by the hopping roller 32. 11a is a front wall of the paper cassette 11, 25 is a paper presser, 26 is a spring,
28 is a nail.

Next, a control section of the printing apparatus having the above-described configuration will be described. FIG. 10 is a control block diagram of the printing apparatus according to the first embodiment of the present invention. In the figure, 41
Is the CPU, 42 is the RO in which the control program is written
M and 43 are RAMs for temporarily storing data; 46 is reception of print data from a host computer (not shown); control of a motor 44; input of a detection signal of a paper feed sensor 33; input of a detection signal of a discharge sensor 34; LED head 2
An I / O port for outputting print data to the printer 9, controlling the electromagnetic magnet 45, and the like.

Next, the operation of the control unit of the printing apparatus when performing double-sided printing will be described. FIG. 11 is a flowchart showing the operation of the printing apparatus according to the first embodiment of the present invention, FIG. 12 is a first diagram showing a transfer state of image data according to the first embodiment of the present invention, and FIG. FIG. 2 is a second diagram illustrating a transfer state of image data according to the first embodiment of the present invention. In FIGS. 12 and 13, “front” indicates one surface of the sheet 27, and “back” indicates the other surface of the sheet 27. Step S1 CPU41
(FIG. 10) receives print data from a host computer (not shown) and analyzes and edits the print data.
One page of image data for one surface of the sheet 27 is developed on the AM 43. Step S2: The sheet is fed by rotating the hopping roller 32. Step S3 R
The image data on the AM 43 is sequentially transferred to the LED head 29 in accordance with the rotation of the photosensitive drum 14. However, at this time, the image data is transferred from the upper side of the page as shown in FIG. Step S4: Printing is performed on one side of the sheet 27. During this time, the CPU 41
Receives the print data from the host computer, analyzes and edits the print data, and starts developing one page of image data on the other side of the sheet 27 on the RAM 43. Step S5 The paper 27 slides on the paper feed guide 36 (FIG. 9) by gravity and moves downward, and the rear end 27a
Are the hopping roller 32 and the paper cassette 11 (FIG. 1).
And the uppermost sheet 27 in the inside. Step S6: The CPU 41 checks the discharge sensor 34,
It waits for the paper 27 to be discharged. Step S7 C
The PU 41 waits until the development of one page of image data on the other side of the sheet 27 is completed. Step S8: The sheet is fed by rotating the hopping roller 32. Step S9: The image data on the RAM 43 is sequentially transferred to the LED head 29 in accordance with the rotation of the photosensitive drum 14. However, at this time, the image data is
The data is transferred from the lower side of the page as shown in FIG.
Step S10: Printing is performed on the other surface of the sheet 27. Step S11 The sheet 27 is discharged to the stacker 31.

In this embodiment, an example in which the present invention is applied to a page printer is described. However, the present invention can be applied to, for example, an ink jet printer. By the way, in the above-described embodiment, the sheet 27 discharged to the paper feed guide 36 is
6, the paper 27 is moved downward by sliding, so that the rear end 27a of the paper 27 does not reliably enter between the hopping roller 32 and the top paper 27 in the paper cassette 11, 28 may not be evenly applied. As a result, the sheet 27 may be fed out at an angle or may be double fed.

Therefore, a second embodiment of the present invention will be described in which the paper 27 is prevented from being fed out at an angle or being double fed in printing on the other surface of the paper 27. FIG. 14 is a schematic diagram of a printing apparatus according to the second embodiment of the present invention. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

In this case, a "U" -shaped conveyance path P11 is formed along the hopping roller 52, and the conveyance path P
A discharge roller 57 is provided at the front end (right end in the figure) of the roller 12 so as to be rotatable in forward and reverse directions. Further, a switching gate 55 as a switching means is disposed on the side of the fixing device 17 from the discharge roller 57 in the conveyance path P12, and the switching gate 55 is switched by an electromagnetic magnet (not shown) to take an upper position and a lower position. When the sheet is placed at the lower position, the paper path 2
7 is guided to the stacker 31, and the paper 27 is guided to the paper feed guide 58 by enabling the paper feed guide 58 as a medium guiding means when placed at the upper position. The paper feed guide 58 extends from a portion adjacent to the discharge roller 57 so as to be inclined toward the hopping roller 52 and the front end of the paper cassette 11 as a medium storage unit.

Paper feed roller 13 in the conveyance path P11
Further on the hopping roller 52 side, the hopping roller 5
The entrance sensor 59 for detecting whether or not the sheet 27 fed by the sheet 2 has reached the sheet feed roller 13 is provided with a conveyance path P.
A writing sensor 60 for detecting whether the paper 27 has been correctly fed between the paper feed roller 13 and the photoconductor drum 14 in FIG.
An exit sensor 61 for detecting whether or not the sheet 27 has been correctly ejected is provided between the switch 7 and the switching gate 55. Then, the timing of exposure to the photosensitive drum 14 is determined based on the detection result of the writing sensor 60, and based on the detection result of the exit sensor 61, whether printing has been completed normally, and whether the paper 27 has been normally discharged. You can judge whether it was done.

In addition, at the end of the paper feed guide 58 on the front end side of the paper cassette 11, that is, in the vicinity of the hopping roller 52, whether the paper 27 has correctly entered the paper feed guide 58 by the discharge roller 57 and the switching gate 55. And a paper re-feed sensor 62 for detecting whether the paper 27 that has entered the paper feed guide 58 is correctly guided by the paper feed guide 58.

Next, the operation of the printing apparatus when performing one-sided printing will be described. FIG. 15 is a first diagram illustrating a paper feed state during single-sided printing according to the second embodiment of the present invention.
FIG. 6 is a second diagram illustrating a sheet feeding state during single-sided printing according to the second embodiment of the present invention. FIG. 17 is a third diagram illustrating a sheet feeding state during single-sided printing according to the second embodiment of the present invention. FIG. 18 is a diagram showing a discharge state at the time of single-sided printing according to the second embodiment of the present invention.

In this case, one sheet of paper 27 stored in the paper cassette 11 (FIG. 14) is fed by one rotation of the hopping roller 52.
Then, first and second protrusions 52a and 52b are formed on the hopping roller 52, and as shown in FIG.
Normally, the first protrusion 52a is located at the lowest position, and the hopping roller 52 and the sheet 27 are not brought into contact with each other. At the time of paper feeding, as shown in FIGS. 16 and 17, when the hopping roller 52 is rotated in the direction of the arrow, the second protrusion 52b causes the uppermost paper 27 in the paper cassette 11 to frictionally move. Send to the left in the figure. Thus, the sheet 27 is fed out by the hopping roller 52.

When the entrance sensor 59 detects that the paper 27 has reached the paper feed roller 13, the hopping roller 52 is stopped, but the paper 27 is continuously transported by the paper feed roller 13. Subsequently, when the paper 27 reaches the writing sensor 60, the writing sensor 60 detects that the paper 27 has been correctly fed, and when the conveyance timing of the paper 27 is confirmed, the paper 27 is sent to the transfer unit. Can be At this time, a toner image is formed on the photosensitive drum 14, and the toner image is transferred to the transfer roller 56.
Is transferred to the sheet 27. The sheet 27 onto which the toner image has been transferred is transported along the transport path P12 and
7 and the toner image is transferred to the sheet 27 by the fixing device 17.
Is established. In this way, printing is performed on one side of the sheet 27. Subsequently, the paper 27 is conveyed by rotating the discharge roller 57 in the direction of the arrow,
It is discharged to the stacker 31. At this time, the switching gate 55
Is placed in the lower position, as shown in FIG. 11a is a front wall of the paper cassette 11, 25 is a paper presser, 26 is a spring, 28 is a claw, 58 is a paper feed guide, 61
Is an exit sensor, and 62 is a re-feed sensor.

Next, the operation of the printing apparatus when performing double-sided printing will be described. The operation from the feeding of the sheet 27 accommodated in the sheet cassette 11 by the hopping roller 52 to the fixing of the toner image on the sheet 27 by the fixing device 17 is the same as the case of performing one-sided printing. The description is omitted. FIG. 19 is a first diagram illustrating a refeeding state during duplex printing according to the second embodiment of the present invention.
FIG. 20 is a second diagram illustrating a state of refeeding during duplex printing according to the second embodiment of the present invention. FIG. 21 is a diagram illustrating refeeding during duplex printing according to the second embodiment of the present invention. FIG. 22 is a third diagram showing a paper state, FIG. 22 is a fourth diagram showing a re-feeding state at the time of double-sided printing in the second embodiment of the present invention, and FIG. 23 is a second embodiment of the present invention. FIG. 24 is a fifth diagram showing the state of re-feeding during duplex printing, and FIG. 24 is a time chart showing the operation of the printing apparatus according to the second embodiment of the present invention.

As shown in FIG. 19, when the rear end 27a of the sheet 27 passes through the exit sensor 61, and when the time t1 elapses from the time when the exit sensor 61 is turned off, the rear end 27a is sandwiched. , The discharge roller 57 is stopped, an electromagnetic magnet (not shown) is turned on, the switching gate 55 is placed at the upper position, and the paper feed guide 58 is activated. When the time t2 elapses after the discharge roller 57 is stopped, as shown in FIG. 20, the discharge roller 57 is rotated in the reverse direction (the direction of the arrow), and the sheet 27 is conveyed in the reverse direction. You.

As a result, the paper 27 is conveyed in the paper feed guide 58 toward the hopping roller 52. And
When the rear end 27a passes through the paper re-feed sensor 62 and a time t3 elapses from the time when the paper re-feed sensor 62 is turned on, the hopping roller 52 and the paper feed roller 13 start rotating. At this time, as shown in FIG.
The rear end 27a reaches the claw 28 of the paper cassette 11.

The sheet 27 conveyed through the sheet feed guide 58 is placed on the top of the sheet 27 in the sheet cassette 11. Therefore, as shown in FIGS. 22 and 23, when the hopping roller 52 makes one rotation in the direction of the arrow, only the paper 27 conveyed through the paper feed guide 58 is fed out. And the paper 27
Is detected by the entrance sensor 59, the hopping roller 52 is stopped, but the paper 27 is continuously transported by the paper feed roller 13.

Subsequently, when the paper 27 reaches the writing sensor 60, it is detected by the writing sensor 60 that the paper 27 has been correctly fed, and when the conveyance timing of the paper 27 is confirmed, the paper 27 is transferred. Sent to the department. At this time,
A toner image is formed on the photoreceptor drum 14 (FIG. 14).
Is transferred to the other side of. Paper 2 on which toner image is transferred
7 is transported along the transport path P12 and sent to the fixing device 17, where the toner image is fixed on the paper 27. In this way, printing is performed on the other side of the sheet 27.

Subsequently, the rear end (the front end in the transport direction of the sheet 27) 27a passes through the outlet sensor 61, and when the outlet sensor 61 is turned on, the discharge roller 57 is stopped and the electromagnetic magnet is turned on. Then, the switching gate 55 is placed at the lower position, and the transport path P12 is enabled. Then, when a time t4 has elapsed since the discharge roller 57 was stopped, the discharge roller 57 is rotated in the forward direction. As a result, the paper 27 is conveyed by the discharge rollers 57 and discharged to the stacker 31.

The paper feed roller 13 has a write sensor 60 that detects the front end of the paper 27 (the rear end in the transport direction of the paper 27).
And the writing roller 60 is stopped when the writing sensor 60 is turned off, and the discharge roller 57 is moved for a time t5 from the time when the rear end 27a passes the outlet sensor 61 and the outlet sensor 61 is turned off. Is stopped when elapses. In this way, the paper 27 after the double-sided printing is discharged to the stacker 31 and is stacked (discharged). Reference numeral 11a denotes a front wall of the paper cassette 11, 25 denotes a paper presser, and 26 denotes a spring.

Next, the operation of the printing apparatus when performing double-sided printing will be described. FIG. 25 is a flowchart illustrating the operation of the printing apparatus according to the second embodiment of the present invention. Step S21 The CPU 41 (FIG. 10) receives print data from a host computer (not shown),
The print data is analyzed and edited, and the paper 2 is stored in the RAM 43.
7 (FIG. 14) is developed for one page of image data. Step S22 The hopping roller 52 is rotated to feed paper. Step S23 RAM
The image data on 43 is sequentially transferred to the LED head 29 in accordance with the rotation of the photosensitive drum 14. However, at this time, the image data is transferred from the upper side of the page as shown in FIG. Step S24 Paper 27
Is printed on one side of. During this time, CPU4
1 receives print data from a host computer, analyzes and edits the print data,
The development of one page of image data is started for the other side of. Step S25: When the rear end 27a of the sheet 27 passes through the exit sensor 61 and the time t1 has elapsed from the time when the exit sensor 61 is turned off, the discharge roller 57 is stopped with the rear end 27a sandwiched therebetween, and With the electromagnetic magnet turned on, the switching gate 55 is placed in the upper position. Further, a time t2 after the discharge roller 57 is stopped.
Is elapsed, the discharge roller 57 is rotated in the reverse direction.
Step S26 The CPU 41 waits for the development of one page of image data to be completed for the other side of the sheet 27. Step S27: rear end 27a of paper 27a
When the time t3 elapses from the point when the sheet passes through the re-feed sensor 62 and the re-feed sensor 62 is turned on, the rotation of the hopping roller 52 and the feed roller 13 is started. Step S28: The image data on the RAM 43 is sequentially transferred to the LED head 29 in accordance with the rotation of the photosensitive drum 14. However, at this time, the image data is
Is transferred from the bottom of the page as shown in Step S29: Printing is performed on the other side of the sheet 27. Step S30: When the rear end 27b passes through the outlet sensor 61 and the outlet sensor 61 is turned on, the discharge roller 5
7 is stopped and the switching gate 55 is placed at the lower position. Then, when the time t4 elapses after stopping the discharge roller 57, the discharge roller 57 is rotated in the forward direction. As a result, the paper 27 is conveyed by the discharge rollers 57 and discharged to the stacker 31. Step S31: The rear end 27a passes through the exit sensor 61, and the exit sensor 61
When the time t5 elapses from the time point when is turned off, the discharge roller 57 is stopped.

As described above, in the present embodiment, the discharge roller 57 disposed adjacent to the stacker 31 is rotatable in the forward and reverse directions, and the discharge roller 57 and the front end of the sheet cassette 11 are rotated. A paper feed guide 58 for feeding the paper 27 is disposed between the two, and a switching gate 55 for switching between discharging and re-feeding the paper 27 is provided. In order to
There is no need to form additional transport paths.

Accordingly, not only the size of the printing apparatus can be reduced, but also the cost of the printing apparatus can be reduced. Further, the sheet 27 is sent to a sheet feed guide 58, and the trailing end 27a is connected to the hopping roller 52 and sheet cassette
Since the reversal of the sheet 27 can be completed only by placing the sheet 27 between the sheet 27 and the front end, the time for reversing the sheet 27 can be shortened.

Further, in the above-described embodiment, the paper 27 is rotated by rotating the discharge roller 57 in the reverse direction.
Is moved toward the hopping roller 52 along the paper feed guide 58, so that the rear end 27a
Surely enters between the hopping roller 52 and the uppermost sheet 27 in the sheet cassette 11 and hits the claw 28 evenly. Therefore, it is possible to prevent the sheet 27 from being fed out at an angle or from being double fed.

Next, a third embodiment of the present invention will be described. FIG. 26 is a schematic diagram of a printing apparatus according to the third embodiment of the present invention. In addition, about what has the same structure as 2nd Embodiment, the description is abbreviate | omitted by attaching the same code | symbol. In the figure, reference numeral 11 denotes a paper cassette as a medium storage means for storing paper 27 as a medium, and a paper presser 25 is provided below the paper cassette 11 and is opposed to the paper presser 25. A circular hopping roller 72 is rotatably provided. The paper presser 25 is swingably supported by a pin 25a, and is urged by a spring 26 to press the paper 27 against a hopping roller 72.

The hopping roller 72 is connected to, for example, a pulse motor as driving means (not shown).
By driving the pulse motor in the forward and reverse directions, it can be rotated in the forward and reverse directions. A “U” -shaped transport path P along the hopping roller 72
A discharge roller 57 is provided at the front end (right end in the figure) of the transport path P22 so as to be rotatable in the forward and reverse directions. Further, a switching gate 55 as switching means is disposed on the side of the fixing device 17 from the discharge roller 57 in the transport path P22, and the switching gate 55 is switched by an electromagnetic magnet (not shown) to take an upper position and a lower position. When placed at the lower position, the transport path P22
Is activated, and the sheet 27 is sent to the stacker 31. When the sheet 27 is placed at the upper position, a sheet feed guide 58 as a medium guide means is provided.
Is activated, and the sheet 27 is sent to the sheet feed guide 58. The paper feed guide 58 extends obliquely from a portion adjacent to the discharge roller 57 toward the front end of the paper cassette 11.

Then, a write sensor 73 for detecting whether or not the paper 27 has been correctly fed between the paper feed roller 13 and the photosensitive drum 14 in the transport path P21.
Is the fixing device 17 and the switching gate 55 in the transport path P22.
An exit sensor 61 for detecting whether or not the sheet 27 has been correctly ejected is provided between the first and second sheets. Also, in the paper feed guide 58, in the vicinity of the hopping roller 72, whether the paper 27 has correctly entered the paper feed guide 58 by the discharge roller 57 and the switching gate 55, and whether the paper 27 that has entered the paper feed guide 58 A sheet re-feed sensor 62 for detecting whether or not the sheet is correctly guided by the guide 58 is provided.

Then, a film 81 is attached to the lower end of the paper feed guide 58, and the top sheet 27 in the paper cassette 11 is pressed by the leading end of the film 81. Note that the printing operation and the discharging operation are the same as those in the second embodiment, and a description thereof will be omitted.

Next, the operation of the printing apparatus when performing one-sided printing will be described. FIG. 27 is a diagram illustrating a paper feed state during single-sided printing according to the third embodiment of the present invention. In this case, the paper 2 stored in the paper cassette 11 (FIG. 26)
7 indicates that the hopping roller 72 is 1 in the forward direction (arrow direction).
By rotating, the uppermost sheet 27 in the sheet cassette 11 is fed to the left side by friction and is fed out.

When the paper 27 reaches the paper feed roller 13 and further reaches the write sensor 73, the write sensor 7
3, it is detected that the sheet 27 has been correctly fed, and the hopping roller 72 is stopped.
7 is continuously transported by the paper feed roller 13. At this time, the transfer timing of the sheet 27 is confirmed,
The sheet 27 is sent to the transfer section.

Next, the operation of the printing apparatus when performing double-sided printing will be described. The operation from the feeding of the sheet 27 accommodated in the sheet cassette 11 by the hopping roller 72 to the fixing of the toner image on the sheet 27 by the fixing device 17 is the same as the case of performing one-sided printing. The description is omitted. 25 is a paper presser,
26 is a spring, 58 is a paper feed guide, and 62 is a paper re-feed sensor.

FIG. 28 is a first diagram showing a sheet feeding state during double-sided printing according to the third embodiment of the present invention. FIG. 29 is a sheet feeding state during double-sided printing according to the third embodiment of the present invention. FIG. 30 is a third diagram illustrating a paper feed state during double-sided printing according to the third embodiment of the present invention, and FIG. 31 is a diagram illustrating a printing apparatus according to the third embodiment of the present invention. 6 is a time chart illustrating an operation. In addition, about what has the same structure as 2nd Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

In this case, similarly to the second embodiment, as shown in FIG. 19, the rear end 27a of the sheet 27 passes through the exit sensor 61, and the time from when the exit sensor 61 is turned off is time. When the time t1 has elapsed, the discharge roller 57 is stopped with the rear end 27a interposed therebetween, and an electromagnetic magnet (not shown) is turned on to switch the switching gate 55.
Is placed in the upper position, and the paper feed guide 58 is activated.
Then, when the time t2 elapses after the discharge roller 57 is stopped, the discharge roller 57 is rotated in the reverse direction (the direction of the arrow in FIG. 28), and the sheet 27 is conveyed in the reverse direction.

As a result, as shown in FIG. 28, the sheet 27 is conveyed in the sheet feed guide 58 toward the hopping roller 72. Then, when the rear end 27a passes through the re-feed sensor 62 and the re-feed sensor 62 is turned on,
As shown in FIG. 29, the hopping roller 72 is rotated in the reverse direction (arrow direction) for a time t6 until the paper 27 reaches the front end of the paper cassette 11, and The front end 27b of the sheet 27 is moved in the direction opposite to the feeding (the direction of arrow E).

Next, when the time t6 has elapsed, the hopping roller 72 is temporarily stopped (once).
At this time, the paper 27 conveyed in the paper feed guide 58 reaches the front end of the paper cassette 11 and the rear end 27.
a contacts the hopping roller 72. Subsequently, FIG.
When the hopping roller 72 and the paper feed roller 13 are rotated in the forward direction (the direction of the arrow) as shown in FIG.
Only the paper 27 conveyed in the paper feed guide 58 is fed out.

The paper 27 in the paper cassette 11 is
Since the movement is regulated at the rear end of the paper cassette 11, the paper 27 is rotated in the reverse direction, and the front end 27b of the uppermost paper 27 in the paper cassette 11 is moved in the direction of arrow E. , Near the front end 27b tends to bend. However, the top sheet 27 in the sheet cassette 11 is moved by the leading edge of the film 81 to the hopping roller 7.
2, the front end 27b is prevented from curving.

When the paper 27 reaches the paper feed roller 13 and further reaches the write sensor 60 and the write sensor 60 is turned on, the hopping roller 52 is stopped, but the paper 27 is 13 is continuously transported. At this time, the writing sensor 73 detects that the paper 27 has been correctly fed, and when the transport timing of the paper 27 is confirmed, the paper 27 is sent to the transfer unit. At this time, a toner image is formed on the photosensitive drum 14, and the toner image is transferred to the other surface of the sheet 27 by the transfer roller 56. The sheet 27 onto which the toner image has been transferred is conveyed along the conveyance path P22 and sent to the fixing device 17, where the toner image is transferred to the sheet 2 by the fixing device 17.
7 is fixed. In this way, printing is performed on the other side of the sheet 27.

Subsequently, the trailing end (the leading end in the transport direction of the sheet 27) 27a passes through the outlet sensor 61, and when the outlet sensor 61 is turned on, the discharge roller 57 is stopped and the electromagnetic magnet is turned on. Then, the switching gate 55 is placed at the lower position, and the transport path P22 is enabled. Then, when a time t4 has elapsed since the discharge roller 57 was stopped, the discharge roller 57 is rotated in the forward direction. As a result, the paper 27 is conveyed by the discharge rollers 57 and discharged to the stacker 31.

As described above, in the present embodiment, the hopping roller 72 is moved before the sheet 27 conveyed through the sheet feed guide 58 reaches the front end of the sheet cassette 11.
Is rotated in the reverse direction, the rear end 27a of the paper 27 stored in the paper cassette 11 is moved in the reverse direction, and then the hopping roller 72 is moved in the forward direction after the paper 27 reaches the front end of the paper cassette 11. Since the paper 27 is rotated to feed out, only the paper 27 after printing on one surface is completed can be reliably fed out.

In each of the above embodiments, an example in which the present invention is applied to an electrophotographic printer has been described.
The present invention can be applied to a copying machine, a multifunctional printer, a facsimile machine, an ink jet printer, and the like. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention.
They are not excluded from the scope of the invention.

[0061]

As described above in detail, according to the present invention, in a printing apparatus, a medium accommodating means for accommodating a medium is rotated by a driving means, and the medium accommodating means is rotated with the rotation. A hopping roller for paying out the medium inside, a printing means for printing on the medium fed by the hopping roller, a discharge roller for discharging the medium after the printing has been performed; A stacker for stacking the medium discharged by the discharge roller, a medium guide means disposed to be inclined and guiding the medium discharged by the discharge roller to a hopping roller, and switchably disposed. Switching means for selectively feeding the medium discharged by the discharge roller to the stacker and the medium guiding means.

In this case, since the medium guiding means is formed between the stacker and the medium accommodating means, it is not necessary to additionally form a conveying path for reversing the sheet. Therefore, not only the size of the printing apparatus can be reduced, but also the cost of the printing apparatus can be reduced. In addition, the medium can be turned over only by feeding the medium to the medium guiding means and placing the rear end of the medium between the hopping roller and the front end of the medium storage means. Can be shorter.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a printing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic side view of a conventional printing apparatus.

FIG. 3 is a perspective view of the printing apparatus according to the first embodiment of the present invention.

FIG. 4 is a first diagram illustrating a paper feed state during single-sided printing according to the first embodiment of the present invention.

FIG. 5 is a second diagram illustrating a sheet feeding state during single-sided printing according to the first embodiment of the present invention.

FIG. 6 is a third diagram illustrating a paper feed state during single-sided printing according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a discharge state during single-sided printing according to the first embodiment of the present invention.

FIG. 8 is a first diagram illustrating a refeeding state during double-sided printing according to the first embodiment of the present invention.

FIG. 9 is a second diagram illustrating a refeeding state during duplex printing according to the first embodiment of the present invention.

FIG. 10 is a control block diagram of the printing apparatus according to the first embodiment of the present invention.

FIG. 11 is a flowchart illustrating an operation of the printing apparatus according to the first embodiment of the present invention.

FIG. 12 is a first diagram illustrating a transfer state of image data according to the first embodiment of the present invention.

FIG. 13 is a second diagram illustrating a transfer state of the image data according to the first embodiment of the present invention.

FIG. 14 is a schematic diagram of a printing apparatus according to a second embodiment of the present invention.

FIG. 15 is a first diagram illustrating a paper feeding state during single-sided printing according to the second embodiment of the present invention.

FIG. 16 is a second diagram illustrating a paper feed state during single-sided printing according to the second embodiment of the present invention.

FIG. 17 is a third diagram illustrating a sheet feeding state during single-sided printing according to the second embodiment of the present invention.

FIG. 18 is a diagram illustrating a discharge state at the time of single-sided printing according to the second embodiment of the present invention.

FIG. 19 is a first diagram illustrating a paper refeeding state during duplex printing according to the second embodiment of the present invention.

FIG. 20 is a second diagram illustrating a refeeding state during duplex printing according to the second embodiment of the present invention.

FIG. 21 is a third diagram illustrating a refeeding state during duplex printing according to the second embodiment of the present invention.

FIG. 22 is a fourth diagram illustrating the state of re-feeding during double-sided printing according to the second embodiment of the present invention.

FIG. 23 is a fifth diagram illustrating a re-feed state during duplex printing according to the second embodiment of the present invention.

FIG. 24 is a time chart illustrating an operation of the printing apparatus according to the second embodiment of the present invention.

FIG. 25 is a flowchart illustrating an operation of the printing apparatus according to the second embodiment of the present invention.

FIG. 26 is a schematic diagram of a printing apparatus according to a third embodiment of the present invention.

FIG. 27 is a diagram illustrating a sheet feeding state during single-sided printing according to the third embodiment of the present invention.

FIG. 28 is a first diagram illustrating a paper feed state during duplex printing according to the third embodiment of the present invention.

FIG. 29 is a second diagram illustrating a paper feed state during double-sided printing according to the third embodiment of the present invention.

FIG. 30 is a third diagram illustrating a paper feed state during double-sided printing according to the third embodiment of the present invention.

FIG. 31 is a time chart illustrating an operation of the printing apparatus according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Paper cassette 14 Photoreceptor drum 16 Developing roller 17 Fixing device 27 Paper 29 LED head 30, 55 Switching gate 31 Stacker 32, 52, 72 Hopping roller 32a, 52a First projection 32b, 52b Second projection 32c Notch 35, 57 Discharge rollers 36, 58 Paper feed guide 53 Charging roller 54 Cleaning roller 56 Transfer roller

Claims (5)

[Claims] (A) a medium storing means for storing a medium; (b) a hopping roller which is rotated by a driving means and feeds out the medium in the medium storing means with the rotation; A printing unit that prints on the medium fed by the hopping roller; (d) a discharge roller that discharges the medium after printing is performed; and (e) a print unit that is disposed above the medium storage unit and A stacker for stacking the medium discharged by the discharge roller; (f)
A medium guiding means disposed to be inclined and guiding the medium discharged by the discharge roller to a hopping roller;
(G) A printing apparatus, comprising: switching means disposed so as to be switchable and selectively sending the medium discharged by the discharge roller to the stacker and the medium guiding means. 2. The printing apparatus according to claim 1, wherein the medium guiding means extends from below the stacker toward the hopping roller. 3. The printing apparatus according to claim 1, wherein the hopping roller has a notch formed in a predetermined range in a circumferential direction, and the notch forms first and second protrusions. 4. The medium guide means extends toward the hopping roller from a position adjacent to the switching means, and the discharge roller moves forward and backward in accordance with switching of the switching means. 2. The method of claim 1, wherein
A printing device according to claim 1. 5. The printing apparatus according to claim 4, wherein the hopping roller is rotated in a reverse direction before the medium conveyed through the medium guiding means reaches the hopping roller.