JPH0930670A - Printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a printing device in a small construction by stopping transmission of the driving force to a shaft using a changeover means when a medium sensor senses passage of a medium, and putting a transport roller in idling condition relative to the shaft. SOLUTION: When the second medium sensor senses passage of a sheet of paper, a control part stops current feed to a coil 30, and then an actuator 27 is rotated by the energizing force of a spring 29. Accordingly a feed roller shaft 7 moves in the direction of Arrow D, and the second coupling part 26 separates from the first coupling part 25. Then the external drive motive for the feed roller shaft 7 ceases. Pins 22a, 22b are set off from notches 23a, 23b, and transport rollers 6a, 6b are put in idling condition relative to the feed roller shaft 7. The transport rollers 6a, 6b continue idling with the frictional force of sheet until its trailing edge has passed pressure rollers 20a, 20b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus for feeding a medium loaded in a medium cassette to a conveying path for printing.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic printer which is a printing device, a paper cassette on which paper is stacked is detachably attached to the main body of the device. A paper feed roller attached to a shaft connected to a drive source is disposed above the paper cassette. Then, a transport path for transporting the sheet is formed from the sheet cassette to the discharge port for discharging the sheet. In the vicinity of the paper cassette and on the downstream side of the paper cassette in the paper transport direction, a transport roller attached to a shaft connected to a drive source and a transport roller.
And a pressure roller that is pressed against the roller.

When printing is performed on a sheet and the sheet is ejected to the outside of the apparatus main body, one sheet stacked in the sheet cassette is delivered to a conveying path by a sheet feeding roller arranged above the sheet cassette. . The fed-out sheet is conveyed to the transfer unit by a pair of conveying rollers provided on the conveying path.

On the other hand, in the printing process section, an electrostatic charge is applied to the surface of the photosensitive drum, which is an image bearing member, by a charger, and L
An electrostatic latent image is formed by a light source such as an ED head, and the electrostatic latent image on the surface of the photosensitive drum is visualized by a developing device.
Form an image. Then, this toner image is transferred onto the conveyed paper by a transfer device provided so as to face the photosensitive drum.

After the toner image is transferred by the transfer device, the paper is further conveyed through the conveying path, and the toner image is fixed in the fixing section. The sheet after fixing is discharged to the outside of the apparatus main body by a discharge roller which is another transport roller. At this time, the rear end of the sheet is still in the sheet cassette.

[0006]

In the conventional printing apparatus described above, since the paper feed roller and the transport roller are attached to different shafts, the mounting space inside the apparatus becomes large, There is a problem that the device cannot be downsized.

[0007]

In order to solve the above-mentioned problems, a solution means provided by the present invention is to feed a medium loaded in a medium cassette to a conveying path by a sheet feeding roller and to convey the medium by a conveying roller. When the medium is further transported to the downstream of the transport path and reaches the other transport roller, another transport roller transports the medium together with the transport roller, and another transport roller further transports the medium. In the printing apparatus, the paper feed roller and the feed roller are attached and driven with the paper feed roller fixed and the feed roller fixed or idling selectable. The rotating shaft, the switching means for switching the transmission of the driving force to the shaft, and the switching between the fixed state and the idling state of the conveyor roller, and the vicinity of another conveyor roller. And is installed upstream of another transport roller in the medium ejection direction. The medium detection sensor for detecting passage, the feeding roller fixed to the shaft and driven to the shaft by the switching means at the time of feeding and at the time of carrying by the carrying roller coaxial with the paper feeding roller. When a force is transmitted and the medium detection sensor detects a medium, the control means for stopping the transmission of the driving force to the shaft by the switching means and for idling the transport roller with respect to the shaft is provided. It is a thing.

[0008]

When the medium loaded in the medium cassette is delivered to the transport path and is transported, the control section first performs switching by the switching means. Then, the transport roller is fixed to the shaft, the shaft rotates, and the paper feed roller feeds the medium from the medium cassette to the transport path, and the medium is fed by the paper feed roller and the transport roller. Are transported along the transport path.

When the medium is further conveyed, the medium detection sensor detects the passage of the medium, and when the medium reaches another conveyance roller, the control unit returns the switching means to the original state. Then, the drive of the rotation of the shaft from the outside stops, and with it,
The transport roller is idling with respect to the shaft. On the other hand, the paper feed roller idles together with the shaft until the trailing edge of the paper comes off.

In a state where the medium is sandwiched between another transport roller and a transport roller coaxial with the paper feed roller, a driving force is applied to the other transport roller. , The feeding roller on the same axis as the paper feeding roller, even if the driving force is not applied,
Rotate. At this time, if the transport roller is fixed to the shaft, when the transport roller rotates, the paper feed roller also rotates, and the medium to be printed next is fed out from the medium cassette.

However, since the transport roller coaxial with the paper feed roller is not fixed to the shaft and is in the idling state, the shaft is not rotated. Therefore, even if the paper feed roller and the transport roller are provided on the same axis, the paper feed roller does not feed the medium to be printed next from the medium cassette.

Then, the medium is transferred by another transport roller.
Further, it is transported on the transport path.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. The elements common to the drawings are designated by the same reference numerals. FIG. 1 is a partial perspective view showing the relationship between a paper feed roller shaft and each roller according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing the configuration of an electrophotographic printer according to the embodiment. FIG. 4 is an explanatory diagram showing the relationship between the paper feed roller shaft and each roller according to the embodiment.

First, the structure of the electrophotographic printer will be described. In FIG. 2, the electrophotographic printer 1 is equipped with a paper cassette 3 that contains paper 2 as a medium. The electrophotographic printer 1 includes a paper cassette 3
In succession, the conveyance path 4 is formed downstream in the paper conveyance direction to the discharge unit 16. Above the paper cassette 3, a paper feed roller 5 for feeding the paper 2 to the transport path 4 and transport rollers 6 a, 6 b for transporting the paper 2 along the transport path 4.
Is attached to a paper feed roller shaft 7 whose both ends are stretched over a frame (not shown). The relationship between the paper feed roller shaft 7, the paper feed roller 5, and the transport rollers 6a and 6b will be described later in detail.

A pressing pad 39, which is pressed against the paper feeding roller 5 by a spring (not shown), is provided in the conveying path 4 near the paper cassette 3, and a plurality of papers 2 fed from the paper cassette 3 are provided. The paper feed roller 5 is pressed so as not to feed the sheets at the same time.

The electrophotographic printer 1 is also provided with a photosensitive drum 8 as an image carrier for carrying a toner image which will be described later. Around the photoconductor drum 8, a temporary charger 9 that applies an electrostatic charge to the surface of the photoconductor drum 8 is provided.
Then, the toner is carried by the toner carrying roller 11 from an LED head 10 which forms an electrostatic latent image on the photosensitive drum 8 and an unillustrated toner cartridge, and is charged to a predetermined polarity. Developing roller 12 which attaches the toner to the electrostatic latent image
A transfer device 13 for transferring the toner image formed on the surface of the photoconductor drum 8 onto the sheet 2, and a cleaning means 1 for removing the residual toner remaining on the surface of the photoconductor drum 8 after the transfer.
4 are provided.

The electrophotographic printer 1 is further provided with a fixing device 15 for fixing the transferred toner onto the sheet 2 along the conveying path 4 downstream of the photosensitive drum 8 in the sheet conveying direction. The fixing device 15 is provided with a heating roller 15a that accommodates a heat source such as a halogen lamp and a pressure roller that is opposed to the heating roller 15a and is pressed by the heating roller 15a with a constant force. -La 15b. Along the transport path 4 downstream of the fixing device 15 in the paper transport direction,
A paper output roller 17a for discharging the paper 2 to the paper output unit 16 is provided. The pressure roller 17b is pressed against the paper discharge roller 17a with a constant force.

A first medium detection sensor 18 is provided in the transport path 4 between the transport rollers 6a and 6b and the transfer device 13. A second medium detection sensor 19 is provided between the fixing device 15 and the paper discharge roller 17a to detect passage of the paper 2. The distance between the first medium detection sensor 18 and the transfer device 13 is set longer than the distance (perimeter) of the photoconductor drum 8 from the LED head 10 to the transfer device 13.

Next, the relationship between the paper feed roller shaft 7, the paper feed roller 5, and the transport rollers 6a and 6b will be described. FIG.
2, the paper feed roller 5 is attached to the paper feed roller shaft 7 in a state of being fixed in the rotation direction, and the transport rollers 6a and 6b are attached to the paper feed roller shaft 7 with respect to the paper feed roller shaft 7. It is installed in a state where it can rotate freely (idle state). Transport roller 6
Pressure rollers 20a and 20b are pressed against a and 6b by springs 21a, 21b, 21c and 21d, respectively.

2 and 3, the paper feed roller shaft 7 is integrally formed with a pin 46. The pin 46 is slidably fitted in a notch portion 47 formed in the paper feeding roller 5. Therefore, when the paper feed roller shaft 7 moves in the direction of arrow C, the pin 46 moves from the one end 47a side of the notch portion 47 to the other end 47b side, and the paper feed roller shaft 7
When the arrow returns to the direction of arrow D, the pin 46 moves from the other end 47b side of the notch portion 47 to the one end 47a side. Since the pin 46 is fitted, the paper feed roller 5 is always fixed in the rotational direction with respect to the paper feed roller shaft 7, and the paper feed roller shaft 7 is indicated by the arrow C. Even if it moves in the -D direction, the stoppers 35b and 36a formed on the frame (not shown)
The paper feed roller 5 does not move.

The paper feed roller shaft 7 also has pins 22a, 2
2b is integrally formed. And this pin 22
The a and 22b are attachable to and detachable from the cutouts 23a and 23b formed in the transport rollers 6a and 6b, respectively. The pins 22a and 22b are connected to the transport roller 6a,
In the state of being fitted in the cutout portions 23a and 23b of 6b, the conveying rollers 6a and 6b are fixed to the sheet feeding roller shaft 7, and the sheet feeding roller 6a and 6b are fixed. When the shaft 7 rotates, it rotates together. The cutout 23
Since a plurality of a and 23b are provided on the transport rollers 6a and 6b, no matter which position the transport rollers 6a and 6b stop rotating, the pin 2 is formed in the cutout portions 23a and 23b.
2a and 22b can be fitted together.

A gear 24 connected to a drive source, which will be described later, is attached to the paper feed roller shaft 7 in an idle state. The gear 24 is integrally formed with a first coupling portion 25. The paper feed roller shaft 7 has a second coupling portion 2 which meshes with the first coupling portion 25.
6 is fixed.

One end of the paper feed roller shaft 7 is notched, and one end of an actuator 27 made of a magnetic material is engaged with it. The other end of the actuator 27 is engaged with one end of a bracket 28 attached to a frame (not shown). Then, with the engagement point between the actuator 27 and the bracket 28 as a fulcrum, the actuator 27 rotates in the direction of arrow AB. A spring 29 is attached to the actuator 27 and the bracket 28, and the actuator 27 is always pulled toward the bracket 28.

An iron core 31 around which a coil 30 is wound is attached to the other end of the bracket 28.
When the actuator is energized, the actuator 27 causes the spring 2
The actuator 27 is rotated in the direction of the arrow B against the biasing force of the magnet 9 to be attracted to the iron core 31, and the state shown in FIG. 4 is obtained. In the state where the actuator 27 is attracted to the iron core 31, the paper feeding roller shaft 7 moves in the direction of arrow C, so
The coupling portion 26 of is engaged with the first coupling 25. As described above, when the second coupling portion 26 meshes with the first coupling 25, the driving force from the driving source, which will be described later, is transmitted to the paper feeding roller shaft 7 via the gear 24, and the feeding roller shaft 7 is fed. The paper roller shaft 7 rotates.

Even if the paper feed roller shaft 7 moves in the direction of arrow C, the stopper 33 formed on the frame (not shown).
a, 33b, 34a, 34b, the gear 24 is indicated by an arrow C.
Do not move in the direction. Further, even if the paper feed roller shaft 7 moves in the arrow D direction, the gear 24 does not move in the arrow D direction. The transport rollers 6a and 6b are also stoppers 35a, 35b and 36.
Movements in the arrow C direction and the arrow D direction are restricted by a and 36b. Further, the paper feed roller shaft 7 has a bearing 37.
The movement in the arrow EF direction is restricted by a, 37b, 38a, and 38b.

The actuator 27, the bracket 28, the coil 30, and the iron core 31 together form the solenoid 3.
2 are configured.

Next, the control system of the electrophotographic printer 1 having the above configuration will be described. FIG. 5 is a block diagram showing a control system of one embodiment.

In FIG. 5, the control unit 40 has an I / O port.
A driver / driver 41 is connected, and a signal is transmitted to the control unit 40 via the I / O port / driver 41, or a signal from the control unit 40 is transmitted to each member. An interface 42 is connected to the I / O port / driver 41, and the interface 42 is connected to the I / O port / driver 41.
Receives print data transmitted from an external device, for example, the upper PC 43, or transmits data to the upper PC 43. The I / O port / driver 41 also has an L
The ED head 10 is connected, and exposure is performed according to an instruction from the control unit 40.

A RAM 44 is connected to the control unit 40, and the print data transmitted from the host PC 43 is
It is stored in the RAM 44 via the I / O port / driver 41. A coil 30 is further connected to the I / O port / driver 41, and power is supplied according to an instruction from the control unit 40. A drive source 45 is also connected to the I / O port / driver 41 and is driven by the support from the control unit 40 to rotate the gear 24. I / O port
The driver / driver 41 also includes the first medium detection sensor 1
8. The second medium detection sensor 19 is connected and sends the passage of the paper 2 to the control unit 40.

Next, the printing operation of the electrophotographic printer 1 will be described with reference to FIGS. 1, 2, 3, 4, and 5. First, when the control unit 40 issues a paper feed instruction, the coil 30
Is energized. Then, the actuator 27 rotates in the direction of arrow B against the urging force of the spring 29, and the sheet feeding roller
The shaft 7 is moved in the direction of arrow C. Then, as shown in FIG. 4, the second coupling portion 26 meshes with the first coupling portion 25, whereby the rotation of the gear 24 to which the driving force is transmitted is transmitted to the sheet feeding roller shaft 7. Transmitted. Here, when the paper feed roller shaft 7 moves in the direction of arrow C, the pins 22a and 22b are fitted into the cutout portions 23a and 23b of the transport rollers 6a and 6b, respectively. As a result, the transport rollers 6a and 6b are also fixed to the paper feed roller shaft 7 like the paper feed roller 5 and rotate with the rotation of the paper feed roller shaft 7. Become. In addition, the pin 46 is a paper feeding roller.
Although the cutout portion 47 of the roller 5 is moved from the one end 47a side to the other end 47b side, the fixing state of the paper feeding roller 5 to the paper feeding roller shaft 7 does not change.

The paper feed roller 5 feeds the uppermost paper 2 stacked in the paper feed cassette 3 to the transport path 4. The sheet 2 is sandwiched between the sheet feeding roller 5 and the pressing pad 39, and is conveyed in the downstream direction of the conveying path 4. Then, the leading end of the sheet 2 reaches the point where the pressure rollers 20a and 20b are pressed by the transport rollers 6a and 6b, and the pressure roller 20 is pressed.
It is pressed against the transport rollers 6a and 6b by a and 20b.
Then, the paper 2 is fed by the paper feed roller 5 and the transport rollers 6a, 6a.
It will be conveyed by b.

When the sheet 2 is further conveyed, it reaches the first medium detection sensor 18. This first medium detection sensor 1
When the arrival of the paper 2 on the sheet 8 is transmitted to the control unit 40, the control unit 40 causes the LED head 10 to expose the surface of the photoconductor drum 8 to the surface of which the electrostatic charge has been given by the temporary charger 9. , An electrostatic latent image is formed on the photosensitive drum 8. Next, a toner charged to a predetermined polarity by the developing roller 12 is attached to the electrostatic latent image to prepare for transfer.

When the transfer start position of the sheet 2 reaches the point a where the photosensitive drum 8 and the transfer device 13 face each other, the toner image is transferred to the sheet 2. When the toner image formed on the surface of the photoconductor drum 8 is transferred onto the paper 2 by the transfer device 13, the transferred toner is fixed on the paper 2 by the fixing device 15, and the printing is completed. After that, paper 2
Is further transported in the downstream direction of the transport path 4. The fixing device 1
When the leading edge of the sheet 2 reaches the point 5, the sheet 2 is heated and heated.
The driving force of the roller 15a and the pressure roller 15b also conveys the material in the downstream direction of the conveyance path 4.

When the leading end of the sheet 2 reaches the second medium detecting sensor 19 and the passage of the sheet 2 is detected by the second medium detecting sensor 19, the controller 40 causes the coil 3 to move.
Stop energizing to 0. Then, the urging force of the spring 29 causes the actuator 27 to rotate in the direction of the arrow A, resulting in the state shown in FIG. Therefore, the paper feed roller shaft 7 is indicated by the arrow D.
The second coupling portion 26 moves away from the first coupling portion 25 in the direction. Therefore, the rotation driving force from the outside of the paper feed roller shaft 7 is stopped. Also, the pins 22a,
22b is disengaged from the cutouts 23a and 23b, and the transport rollers 6a and 6b are in a state of idling with respect to the paper feed roller shaft 7. On the other hand, the pin 46 has the other end 47 of the cutout portion 47.
Since it only returns from the b side to the one end 47a side, the paper feeding roller 5
The fixed state of the paper feed roller shaft 7 does not change.

At this time, the rear end of the sheet 2 is still in the sheet feeding cassette 3. The leading end of the sheet 2 has a heating roller 15a, a pressure roller 15b, a sheet discharging roller 17a,
It is sandwiched between the pressure rollers 17b and is transported in the downstream direction of the transport path 4.

Although the driving force has not been transmitted to the paper feeding roller shaft 7, the paper feeding roller 5 moves the trailing end of the paper 2 because the paper 2 is being conveyed in the downstream direction of the conveying path 4. The sheet is rotated by the frictional force of the sheet 2 until it passes through the pressing pad 39. When the rear end of the paper 2 passes the pressing pad 39, the paper feed roller 5 does not rotate due to the frictional force of the paper 2, so the paper 2 to be printed next is fed out from the paper feed cassette 3. There is no end.

However, the rear end of the sheet 2 is pressed by the pressing pad 39.
Even if the paper 2 passes through the pressure roller 20a, 2
It is pressed against the transport rollers 6a and 6b by 0b. The transport rollers 6a and 6b run idle due to the frictional force of the sheet 2 until the rear end of the sheet 2 passes through the pressure rollers 20a and 20b.

Since the transport rollers 6a and 6b are idling, the rotations of the transport rollers 6a and 6b are not transmitted to the paper feed roller shaft 7. Therefore, since the paper feed roller 5 does not rotate, the paper 2 to be printed next will not be fed to the transport path 4.

The rear end of the sheet 2 is the pressure roller 20.
After passing the sheets a and 20b, the paper 2 is further transported in the downstream direction of the transport path 4 and discharged to the discharge unit 16.

As described above, in this embodiment, since the number of axes can be reduced, the mounting space of the device can be small. Further, a mechanism for preventing the paper 2 to be printed next from being fed out from the paper cassette 3 is also provided with a paper feeding roll.
The solenoid 32 for switching between rotation and stop of the roller shaft 7 and a member attached to the paper feed roller shaft 7 are used to feed the paper.
Since it is realized by moving the rotary shaft 7, a simple mechanism is sufficient. Therefore, the device can be downsized.

Further, the cutouts 23a and 23b are formed in the transport rollers 6a and 6b, and the pin 2 is attached to the paper feeding roller shaft 7.
It is easy to form 2a and 22b, and the cost is low.

[0042]

Since the present invention is configured as described above, it has the following effects. The paper feed roller is fixed, the transport roller is fixed or idle, and the paper feed roller and the transport roller are attached and the shaft is rotated by being driven. Switching means for switching the presence / absence of transmission of the driving force to the shaft and switching between the fixed state and the idling state of the transport roller, and another transport roller in the vicinity of another transport roller. A medium detection sensor, which is provided upstream of the roller in the medium discharge direction and detects passage of the medium, and a feeding roller by a switching unit at the time of feeding and feeding by the feeding roller coaxial with the paper feeding roller. −
When the driving force is transmitted to the shaft and the medium detecting sensor detects the medium, the switching means stops the transmission of the driving force to the shaft, and the transport roller is stopped. The number of shafts can be reduced by providing the control unit that makes the shafts idle. Further, since the mechanism for preventing the medium to be printed next from being fed out from the medium cassette is also only the switching means, a simple mechanism is sufficient. Therefore, the device can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a paper feed roller shaft and rollers according to an embodiment of the present invention.
It is a partial perspective view which shows the relationship with LA.

FIG. 2 is an explanatory diagram showing a configuration of an electrophotographic printer according to an embodiment.

FIG. 3 is an explanatory diagram showing a relationship between a paper feed roller shaft and each roller according to an embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a paper feed roller shaft and each roller according to an embodiment.

FIG. 5 is a block diagram showing a control system of one embodiment.

[Explanation of symbols]

 1 Electrophotographic Printer 2 Paper 5 Feed Rollers 6a, 6b Conveyor Roller 7 Feed Roller Shaft 17a Discharge Roller 19 Second Media Detection Sensor 22a, 22b Pin 24 Gear 25 First Cup Ring part 26 Second coupling part 27 Actuator 29 Spring 32 Solenoid 40 Control part

Claims (3)

[Claims] 1. A medium loaded in a medium cassette is fed to a conveying path by a paper feeding roller, the medium is further conveyed to a downstream side of the conveying path by a conveying roller, and the medium reaches another conveying roller. Then, in a printing apparatus in which another transport roller transports the medium together with the transport roller, and another transport roller further transports the medium, the paper feed roller is fixed and the transport roller is in a fixed state. Is fixed or idling can be selected, the paper feed roller and the conveyance roller are attached, and the axis that rotates by being driven and the switching of the transmission of the driving force to the axis and the conveyance Switching means for switching between a state where the roller is fixed to the shaft and a state where the roller is idling, and a medium which is provided in the vicinity of another transport roller and upstream of the another transport roller in the medium discharge direction. Coordinates with the media detection sensor that detects the passage of paper and the feeding roller and feeding roller. At the time of transport by the transport roller, when the transport roller is fixed to the shaft by the switching means and the driving force is transmitted to the shaft and the medium detection sensor detects the medium, the switching means causes the shaft to move. And a control unit for stopping the transmission of the driving force to the transport roller and for making the transport roller idle around the shaft. 2. The switching means, when driven, moves the shaft in a direction orthogonal to the medium conveying direction, a first coupling portion connected to a drive source, and is attached to the shaft. , The first by the movement of the axis by the movement means
The second coupling part that transmits the driving force to the shaft when fitted to the first coupling part and the second coupling part that is formed on the shaft and is conveyed by the movement of the shaft by the movement of the moving means. When it is fitted to the rollers and then fitted to the conveyor rollers, the conveyor rollers are
The printing apparatus according to claim 1, wherein the printing apparatus comprises a pin for fixing the roller to the shaft. 3. A solenoid for driving the actuator, wherein one end of an actuator is attached to a shaft, and the actuator is driven by the actuator to move the shaft in a direction orthogonal to a medium conveying direction. 3. The printing apparatus according to claim 2, further comprising a spring that pulls the actuator in a direction to return the shaft to its original position when is stopped.