JPH10329974A - Paper conveying mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a printing time when printing is sequentially carried out in two or more paper sheets in a paper conveying device used for a motor type printer in which a driving source is used in common between a printing head and a paper conveying mechanism. SOLUTION: Only the reverse rotating operation is transmitted to a paper feeding roller 20 for feeding a paper sheet. The normal rotating operation and the revere rotating operation of the motor 70 are transmitted to a driving roller 30, and by means of its normal rotation, a paper sheet 10, in which printing is being carried out, is conveyed. The rotation of the driving roller 30 is transmitted to a discharging roller 40 by means of a power transmitting mechanism 80, and the paper sheet 10 is discharged. In the power transmitting mechanism 80, a one-way clutch 83 serving as a power cutoff means is arranged, and reverse rotation of the discharging roller 40 is prevented when the motor 70 is rotated reversely. While the previous paper sheet 10 in which printing is finished is clamped between the discharging roller 40 and its pinch roller 50, the normal rotation of the motor 70 is switched to the reverse rotation for starring feeding of the following paper sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper transport mechanism used in a printer or a printing device in a facsimile machine, and more particularly, to a drive source shared between a print head in a printing unit and a paper transport mechanism. The present invention relates to a paper transport mechanism used in a motor type printing device.

[0002]

2. Description of the Related Art In order to reduce the cost of a printer, a facsimile or the like, a one-motor type printing apparatus has been developed in which a drive source is shared between a print head in a printing section and a paper transport mechanism. This printing device conveys the paper in the stocker toward the printing unit by the reverse rotation of the motor, and drives the print head in the printing unit to pass the paper through the printing unit and discharge it by the forward rotation of the motor. Thus, the print head and the paper transport mechanism are driven by one motor.

FIGS. 10 to 13 show the structure and operation of a conventional paper transport mechanism used in a one-motor type printing apparatus. In each figure, the upper part is a plan view, and the lower part is a side view.

The paper transport mechanism includes a paper feed roller 20 that presses against the paper 10 in the stocker, a drive roller 30 provided in combination with a pinch roller 50 downstream of the paper feed roller 20 in the paper transport direction, A discharge roller 40 provided in combination with the pinch roller 60 is provided downstream of the roller 30 in the sheet conveyance direction. Motor gear 71
Is transmitted to the sheet feed gear 21 on the upstream side in the sheet conveyance direction via the intermediate gear 72, and is also transmitted to the drive gear 31 on the downstream side in the sheet conveyance direction via the intermediate gear 72.

The paper feed gear 21 is connected to a support shaft 23 of the paper feed roller 20 via a one-way clutch 22. The one-way clutch 22 rotates the motor gear 71 in a reverse rotation operation (counterclockwise rotation in the figure). ) Is transmitted to the sheet feeding gear 21 only when the intermediate gear 72 rotates. Thus, the paper feed roller 20 is driven to rotate in the paper feed direction (counterclockwise in the drawing) by the rotation only when the motor performs the reverse rotation operation.

On the other hand, the drive gear 31 is directly connected to a support shaft 33 of the drive roller 30. Therefore, the driving roller 30
Is driven to rotate in both directions with forward rotation (clockwise rotation in the figure) and reverse rotation of the motor. The rotation of the drive gear 31 is also transmitted to the support shaft 43 of the discharge roller 40 on the downstream side in the sheet conveyance direction by a belt 81 as a power transmission mechanism.
Accordingly, the discharge roller 40 is driven to rotate in the same direction as the drive roller 30 when the drive roller 30 rotates.

When printing is performed, as shown in FIG. 10, the motor (motor gear 71) performs a reverse rotation operation. As a result, the paper feed roller 20 is driven to rotate in the paper feed direction (counterclockwise in the drawing), and the first sheet 10 of the sheets stacked in the stocker is sent downstream in the sheet transport direction. At this time, the drive roller 30 is rotationally driven in a counter-feed direction (counterclockwise in the drawing) opposite to the feed roller 20. The friction between the pinch roller 50 and the paper 10 is small. For these reasons, the paper 10 discharged from the stocker
Stops before the drive roller 30 with its front end in the conveyance direction pressed between the drive roller 30 and the pinch roller 50.

In this state, as shown in FIG. 11, the motor (motor gear 71) switches from the reverse rotation operation to the forward rotation operation. Since this rotation is interrupted by the one-way clutch 22, the paper feed roller 20 is in a non-driven state. On the other hand, the drive direction of the drive roller 30 is switched from the counter paper feed direction (counterclockwise in the figure) to the paper feed direction (clockwise in the figure).
The discharge roller 40 is also driven to rotate in the paper feeding direction (clockwise in the figure). As a result, the paper 10 is sent downstream in the transport direction.

At this time, the forward rotation of the motor is transmitted to the print head 100, and the print head 100
By traversing above zero, printing is performed on the paper 10. Since the paper feed roller 20 is not driven, the paper 10 is not continuously fed.

The paper 10 on which printing has been completed is discharged to the downstream side of the discharge roller 40 as the drive roller 30 and the discharge roller 40 continue to be driven, as shown in FIG.

When printing is completed on one sheet, the printing operation is completed. When printing is performed on two or more sheets continuously, as shown in FIG. 13, after the sheet 10 is completely discharged to the downstream side of the discharge roller 40, the motor (motor gear 71) is rotated in reverse from the normal rotation operation. Switch to rotating operation. As a result, the paper 10 in the stocker is sent out to the downstream side in the transport direction again, and thereafter, the same operation is repeated.

Here, the sheet 1 is located downstream of the discharge roller 40.
After 0 is completely discharged, the motor (motor gear 71)
Is changed when the paper 10 is sandwiched between the discharge roller 40 and the pinch roller 60, and when the rotation direction is changed, the driving roller 30 and the discharge roller 40 This is because the paper 10 is driven to rotate in the paper direction (counterclockwise in the drawing) and the paper 10 is fed backward in the direction opposite to the transport direction.

As described above, in the one-motor type printing apparatus in which the drive source is shared between the print head and the paper transport mechanism, the forward rotation of the motor is used for the printing operation including the paper transport, and the reverse rotation of the motor is performed. The operation is to supply paper to the printing unit,
That is, it is used for paper feeding.

[0014]

In a paper transport mechanism used for such a one-motor type printing apparatus, a driving source is shared between the print head and the paper transport mechanism.
When printing is continuously performed on two or more sheets, the leading sheet 10 is moved between the discharge roller 40 and the pinch roller 60.
Is completely removed, it is necessary to switch the rotation direction of the motor from the normal rotation to the reverse rotation for paper feeding, and to start feeding the subsequent paper 10. Otherwise, with the switching of the rotation direction of the motor, the drive roller 30 and the discharge roller 40 are rotationally driven in the counter-feeding direction (counterclockwise in the figure),
This is because the paper 10 is conveyed in the reverse direction to the transport direction, thereby causing a paper jam.

However, in a one-motor type printing apparatus, printing is usually performed by traversing the print head 100 between the drive roller 30 and the discharge roller 40, and the discharge roller 4
Before the paper 10 comes out from between 0 and the pinch roller 60, the substantial printing operation has been completed. For this reason, despite the fact that the actual printing operation has been completed,
Until the sheet 10 is completely discharged, the start of supply of the next sheet 10 is delayed.

Although this is a problem peculiar to a one-motor type printing apparatus in which a drive source is shared between a print head and a paper transport mechanism, the printing time when printing is continuously performed on two or more sheets of paper. Is a major cause of extension.

The present invention has been made in view of the above circumstances, and provides a paper transport mechanism for shortening the printing time when performing printing on two or more sheets continuously while maintaining the one-motor system. The purpose is to do.

[0018]

In a paper transport mechanism according to the present invention, a paper in a stocker is transported toward a printing unit by reverse rotation of a motor, and a print head in the printing unit is driven by forward rotation of the motor. A paper transport mechanism used in a one-motor type printing device in which paper is ejected while passing through a printing unit, and transports paper in a stocker to a downstream side in a transport direction by a reverse rotation operation of a motor. A roller, a drive roller provided in combination with a pinch roller downstream of the paper feed roller in the paper transport direction, and a drive roller for transporting the paper downstream in the transport direction by a forward rotation of the motor; and a pinch downstream of the drive roller in the paper transport direction. A discharge roller that is provided in combination with a roller and discharges paper to the downstream side in the transport direction by a forward rotation of the motor, and a power transmission to the discharge roller when the motor rotates reversely. Or by cutting off the contact of the discharge roller and the paper, and a reverse feed prevention means for preventing the transmission opposite sheet by the reverse rotation of the discharge roller.

More preferably, in the paper transport mechanism according to the present invention, the paper in the stocker is transported toward the printing unit by the reverse rotation of the motor, and the print head in the printing unit is driven by the forward rotation of the motor. A paper transport mechanism used in a one-motor type printing device in which paper is discharged through a printing unit, and a paper feed roller that presses against paper in a stocker and transmits only reverse rotation of the motor. A drive roller provided in combination with a pinch roller on the downstream side of the paper feed direction of the paper feed roller to transmit forward and reverse rotation operations of the motor, and a pinch roller on the downstream side of the drive roller in the paper transport direction. Discharge rollers provided, power transmission means for transmitting the rotation of the motor to the discharge rollers so that the discharge rollers rotate in the same direction as the drive rollers, and power transmission means By transmitting the forward rotation of the motor to the discharge roller and blocking the transmission of the reverse rotation of the motor to the discharge roller, the reverse rotation of the discharge roller during the reverse rotation of the motor allows the paper to be fed backward. And a power shutoff means as a reverse feed prevention means.

In this paper transport mechanism, forward rotation of the motor is transmitted to the discharge roller in a power transmission means for transmitting the rotation of the motor to the discharge roller so that the discharge roller rotates in the same direction as the drive roller. Since the power shutoff means for shutting off the transmission of the reverse rotation operation of the motor to the discharge roller is incorporated, after the substantial printing operation is completed, the sheet is caught between the discharge roller and the pinch roller. Even if the rotation direction of the motor is switched from normal rotation to reverse rotation for paper feeding, the discharge roller is not driven to rotate in the counter paper feeding direction.
Therefore, reverse feeding of the sheet due to reverse rotation of the discharge roller during the reverse rotation operation of the motor is prevented. Therefore, even when the previous sheet is sandwiched between the discharge roller and the pinch roller, it is possible to switch the rotation direction of the motor from the forward rotation to the reverse rotation for sheet feeding, thereby making it possible to switch two or more sheets. In this case, the printing time when printing is continuously performed on the sheet of paper is shortened.

As the power cutoff means, for example, a one-way clutch that transmits only the forward rotation of the motor, or a pendulum gear that meshes with an adjacent gear when the motor rotates forward and separates from the gear when the motor rotates reversely, or the like. Can be used.

When printing is performed continuously on two or more sheets of paper, the rear end of the sheet except for the last sheet in the transport direction passes between the drive roller and the pinch roller, and the sheet is discharged. Control is performed so as to switch from normal rotation to reverse rotation while being sandwiched between the roller and the pinch roller.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a paper transport mechanism according to the embodiment of the present invention, and FIGS. 2 to 5 are explanatory views of the structure and operation of the paper transport mechanism according to the embodiment of the present invention.
2 to 5, the upper part is a plan view, and the lower part is a side view.

As shown in FIG. 1, the paper transport mechanism according to the embodiment of the present invention presses the first sheet of paper 10 stacked and held in an inclined stocker,
A paper feed roller 20 that supplies the sheet of paper 10 to a printing unit;
A drive roller 30 provided downstream of the paper feed roller 20 in the paper transport direction, a discharge roller 40 provided further downstream of the drive roller 30 in the paper transport direction, and a drive source for these rollers and the print head 100 Motor 7 as drive source
0.

The paper feed roller 20 is mounted on the support shaft 23 with an interval in the axial direction. A paper feed gear 21 is attached to one end of the support shaft 23 via a one-way clutch 22. The one-way clutch 22 is connected to the sheet feeding gear 2.
Only the 1 counterclockwise rotation is transmitted to the support shaft 23.

The driving roller 30 is combined with a plurality of pinch rollers 50 disposed above the driving roller 30. A drive gear 31 is directly attached to one end of a support shaft 33 that supports the drive roller 30.

The discharge roller 40 is combined with a plurality of pinch rollers 60 disposed above the discharge roller 40, and is connected to the upstream drive roller 30 by power transmission means 80. The power transmission means 80 is, here, the driving roller 3.
Pulley 82 attached to one end of the support shaft 33
And a one-way clutch 83 attached to the support shaft 43 of the discharge roller 40, and a belt 81 bridged between the pulley 82 and the one-way clutch 83.

The one-way clutch 83 mounted on the support shaft 43 of the discharge roller 40 transmits only the rotation of the motor 70 at the time of normal rotation, and interrupts the rotation transmission of the motor 70 at the time of reverse rotation. The power cut-off means 90 as a feed prevention means is constituted. Specifically, when the belt 81 rotates in the paper feeding direction (clockwise in the drawing), the rotation is transmitted to the support shaft 43 of the discharge roller 40, and the belt 81 is moved in the counter paper feeding direction (counterclockwise in the drawing). , The rotation is not transmitted to the support shaft 43 of the discharge roller 40.

The motor gear 71 attached to the output shaft of the motor 70 meshes with the intermediate gear 71, and the intermediate gear 71 meshes with each of the sheet feed gear 21 and the drive gear 30.

The print head 100 is moved between the drive roller 30 and the discharge roller 40 by the reciprocating traverse operation.
Printing is performed on the paper 10 conveyed on these rollers.

Next, the operation of the paper transport mechanism according to the embodiment of the present invention will be described.

When printing is performed, as shown in FIG. 2, the motor 70 performs a reverse rotation operation (counterclockwise rotation operation in the figure) for paper feeding. Thereby, the motor gear 71
Is driven to rotate counterclockwise, and its rotation is
The paper feed gear 21 is rotated counterclockwise. This rotation is transmitted to the support shaft 23 via the one-way clutch 22. As a result, the paper feed roller 20 is driven to rotate in the counterclockwise direction, and the first sheet 10 of the sheets stacked in the stocker is rotated.
To the downstream side in the paper transport direction.

At this time, the drive roller 30 rotates in the opposite direction (counterclockwise in the figure) to the feed roller 20 by the rotation of the motor gear 71 being transmitted to the drive gear 31 via the intermediate gear 72. Being driven. This rotation direction is
This is the direction in which the paper is fed back. The pinch roller 50 and the paper 10
Friction is small. For this reason, the paper 10 discharged from the stocker stops before the drive roller 30 with the front end in the transport direction pressed between the drive roller 30 and the pinch roller 50.

In this state, as shown in FIG. 3, the motor 70 switches from a reverse rotation operation to a normal rotation operation for printing (clockwise rotation in the figure). Thus, the drive gear 31 and the drive roller 30 are driven to rotate clockwise, that is, in the paper feeding direction. Further, the rotation of the drive gear 31 is transmitted to a one-way crack 83 which is a power cutoff means 90 via a belt 81 of the power transmission means 80. The one-way clutch 83 transmits clockwise rotation, that is, rotation in the paper feeding direction, to the support shaft 43 of the discharge roller 40. For this reason, the discharge roller 40 is driven to rotate in the sheet feeding direction together with the drive roller 30.

On the other hand, the feed gear 21 is driven to rotate clockwise by switching the operation direction of the motor 70.
The one-way clutch 22 does not transmit the rotation to the support shaft 23 of the paper feed roller 20. For this reason, even if the motor 70 performs the forward rotation operation, the paper feed roller 20 is not driven to rotate in the reverse paper feed direction.

Accordingly, the sheet 1 discharged from the stocker
0 is conveyed to the downstream side in the conveyance direction by the drive roller 30 and the discharge roller 40. At this time, the forward rotation of the motor 70 is controlled by the ink jet type print head 10.
0, and the print head 100 traverses over the paper 10 to print on the paper 10.

When printing is completed on one sheet of paper 10, the drive roller 30 and the discharge roller 40 continue to be driven, so that the paper 10 is discharged to the downstream side of the discharge roller 40.

In the case where printing is performed successively on two or more sheets of paper 10 and the sheet 10 is not the final sheet, as shown in FIG. When the paper 10 is sandwiched between the discharge roller 40 and the pinch roller 60 and the trailing end of the paper 10 in the transport direction comes out of the space between the drive roller 30 and the pinch roller 50, the motor 70 rotates forward. To the reverse rotation operation for paper feeding.

As a result, the driving gear 31 and the driving roller 30 are driven to rotate again in the counter-feeding direction. The belt 81 of the power transmission means 80 is driven to rotate in the counter-feeding direction with the rotation of the drive gear 31, and the one-way clutch 83 as the power cutoff means 90 transmits the rotation of the belt 81 to the discharge roller 40. Is not transmitted to the support shaft 43, so that the discharge roller 40 does not rotate. Also, the paper 10 on which printing has been completed has the driving roller 30 and its pinch roller 5 at the rear end in the transport direction.
It is in a state of getting out of between 0. Therefore, even if the motor 70 performs the reverse rotation operation for feeding paper, the printed paper 10 is stopped between the discharge roller 40 and the pinch roller 60 and stopped, and the paper 10 is moved upstream in the transport direction. It will not be sent back to.

Then, when the motor 70 performs a reverse rotation operation for feeding paper, the feeding roller 20 is driven to rotate in the feeding direction, and sends the next sheet 10 from the stocker to the downstream side in the transport direction.

The next sheet 10 sent out from the stocker
When the driving roller 30 is driven to rotate in the counter-sheet feeding direction, the driving roller 30 stops before the driving roller 30 with its front end in the conveyance direction pressed between the driving roller 30 and the pinch roller 50. In this state, as shown in FIG. 5, the motor 70 switches from the reverse rotation operation to the normal rotation operation for printing again. Thereby, the driving gear 3
1 and the driving roller 30 are driven to rotate in the sheet feeding direction. As a result, the next sheet 10 is printed while being transported downstream in the transport direction.

The rotation of the drive gear 31 is transmitted to a one-way crack 83 which is a power cut-off means 90 via a belt 81 of a power transmission means 80. The one-way clutch 83 rotates the paper feed direction in the discharge roller 40. To the support shaft 43. For this reason, the discharge roller 40 also starts rotating in the paper feeding direction, and as a result, the paper 10 which has been printed and stopped between the discharge roller 40 and the pinch roller 60 is stopped.
Starts moving again downstream in the transport direction and is discharged downstream of the discharge roller 40.

Therefore, even if the motor 70 is switched to the reverse rotation operation for feeding paper in a state where the paper 10 on which printing has been completed is sandwiched between the discharge roller 40 and the pinch roller 60, the paper 10 does not interfere with the next sheet 10, so that continuous printing without trouble is performed.

If the paper 10 on which printing has been completed is the final paper, the operation direction of the motor 70 is not switched to the reverse rotation operation for feeding paper, and the normal rotation operation is continued, so that the paper 10 is discharged by the discharge roller. It is discharged downstream of 40.

FIGS. 6 to 9 are explanatory views of the structure and operation of a sheet transport mechanism according to another embodiment of the present invention. In addition,
6 to 9, the upper part is a plan view, and the lower part is a side view.

The paper transport mechanism according to another embodiment of the present invention is different from the above-described paper transport mechanism according to the embodiment of the present invention in that the power transmission for transmitting the rotation of the drive gear 31 to the discharge roller 40 is provided. A means 80 is different from a power cutoff means 90 which is incorporated in the power transmission means 80 and interrupts the rotation transmission of the motor 70 when the motor 70 rotates in the reverse direction.

That is, in the paper transport mechanism according to another embodiment of the present invention, the power transmission means 80 for transmitting the rotation of the drive gear 31 to the discharge roller 40 includes the drive gear 31 and the support shaft 43 of the discharge roller 40. And a pendulum gear 86 disposed between the discharge gears 41 attached to one end of the pendulum.

Here, the pendulum gear 86 constitutes a power cutoff means 90 as a reverse feed prevention means. That is, the pendulum gear 86 is a so-called planetary gear that is mounted on a lever 87 supported by the support shaft 33 of the drive roller 30 and that can revolve around the drive gear 31 while meshing with the drive gear 31. By this revolving operation, the pendulum gear 86 is brought into a state of being meshed with the discharge gear 41 and the discharge gear 4.
It is possible to switch to a state away from 1. More specifically, a switching mechanism (not shown) is in an engaged state when the motor 70 performs a forward rotation operation, and is in a separated state when the motor 70 performs a reverse rotation operation.

The use of the power transmission means 80 and the power cutoff means 90 also enables the motor 70 in a state where the paper 10 on which printing has been completed is sandwiched between the discharge roller 40 and the pinch roller 60 thereof. Is switched to the reverse rotation operation for feeding the paper, the rotation operation is not transmitted to the discharge roller 40, so that the reverse feeding of the paper 10 due to the switching is prevented. Accordingly, by making the switching timing earlier than before, it is possible to reduce the printing time when printing is continuously performed on two or more sheets.

In the above-described embodiment, the power cut-off means 90 incorporated in the power transmission means 80 is used as the reverse feed prevention means. However, the present invention is not limited to this. In some cases, a roller elevating means for lowering the discharge roller 40 to separate it from the paper 10 may be used. Also,
A one-way clutch incorporated in the drive gear 31 may be used.
In the case of this one-way clutch, both the drive roller 30 and the discharge roller 40 are in a non-drive state when the motor 70 rotates in the reverse direction.

[0051]

As described above, the sheet transport mechanism according to the present invention is provided with the reverse feed preventing means for preventing the reverse feed of the sheet due to the reverse rotation of the discharge roller when the motor rotates in the reverse direction. After the printing operation is completed, even if the rotation direction of the motor is switched from normal rotation to reverse rotation for paper feeding while the paper is sandwiched between the discharge roller and the pinch roller,
Since the reverse feed of the paper is prevented, the rotation direction of the motor can be switched from normal rotation to reverse rotation for paper feeding even when the previous paper is sandwiched between the discharge roller and the pinch roller. it can. Therefore, an increase in printing time when printing is performed on two or more sheets continuously, which is a problem in a one-motor type printing apparatus, is avoided, and the printing time is shortened, thereby enabling high-speed printing. Become.

In particular, as the reverse feeding preventing means, the forward rotation operation of the motor is transmitted to the discharge roller in the power transmission means for transmitting the rotation operation of the motor to the discharge roller so that the discharge roller rotates in the same direction as the driving roller. However, in the case of incorporating a power shut-off means for shutting off the transmission of the reverse rotation operation of the motor to the discharge roller, it is only necessary to add a few parts such as a one-way clutch or a pendulum gear to the existing mechanism. Good nature.

[Brief description of the drawings]

FIG. 1 is a perspective view of a paper transport mechanism according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation of the sheet transport mechanism according to the embodiment of the present invention, showing a sheet feeding operation for a first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 3 is an explanatory diagram of an operation of the sheet transport mechanism according to the embodiment of the present invention, showing a printing operation on a first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 4 is an explanatory diagram of an operation of the sheet transport mechanism according to the embodiment of the present invention, showing a sheet feeding operation for the second and subsequent sheets, wherein the upper part is a plan view and the lower part is a side view.

FIG. 5 is an explanatory diagram of the operation of the paper transport mechanism according to the embodiment of the present invention, showing a discharging operation for a preceding paper and a printing operation for a succeeding paper, wherein the upper part is a plan view and the lower part is a side view.

FIG. 6 is an explanatory diagram of an operation of a sheet conveying mechanism according to another embodiment of the present invention, showing a sheet feeding operation for a first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 7 is an explanatory diagram of an operation of a sheet transport mechanism according to another embodiment of the present invention, showing a printing operation on a first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 8 is an explanatory diagram of an operation of a sheet conveying mechanism according to another embodiment of the present invention, showing a sheet feeding operation for a second sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 9 is an explanatory diagram of an operation of a sheet transport mechanism according to another embodiment of the present invention, and illustrates a discharge operation for a first sheet and a second sheet discharge operation.
The printing operation on the second sheet is shown, wherein the upper part is a plan view and the lower part is a side view.

FIG. 10 is an explanatory view of the structure and operation of a conventional sheet transport mechanism, showing a sheet feeding operation for the first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 11 is an explanatory diagram of an operation of a conventional paper transport mechanism, showing a printing operation on a first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 12 is an explanatory view of the operation of the conventional paper transport mechanism, showing a discharge operation for the first sheet, wherein the upper part is a plan view and the lower part is a side view.

FIG. 13 is an explanatory diagram of an operation of the sheet transport mechanism according to the embodiment of the present invention, illustrating a sheet feeding operation for a second sheet,
The upper part is a plan view, and the lower part is a side view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Paper 20 Feed roller 21 Feed gear 22 One-way clutch 30 Drive roller 31 Drive gear 40 Discharge roller 41 Discharge gear 50, 60 Pinch roller 70 Motor 71 Motor gear 72 Intermediate gear 80 Power transmission means 81 Belt 83 One-way clutch (reverse Power cut-off means 90 as feed preventing means) 86 Pendulum gear (power cut-off means 90 as reverse feed preventing means) 100 Print head

Claims (4)

[Claims] 1. A paper in a stocker is conveyed toward a printing unit by a reverse rotation of a motor, and the paper is discharged through a printing unit while a print head in the printing unit is driven by a forward rotation of the motor. A paper transport mechanism used in a one-motor type printing apparatus, comprising a paper feed roller for transporting paper in a stocker downstream in a transport direction by a reverse rotation of a motor, and a paper feed roller downstream of the paper feed roller in a paper transport direction. A drive roller is provided in combination with a pinch roller, and transports the sheet to the downstream side in the transport direction by the forward rotation of the motor.A drive roller is provided in combination with the pinch roller on the downstream side of the drive roller in the paper transport direction, and is provided by the forward rotation of the motor. Discharge rollers that discharge paper downstream in the transport direction and power transmission to the discharge rollers during reverse rotation of the motor or disconnection of paper from the discharge rollers A sheet feeding mechanism, further comprising a reverse feed preventing means for preventing the sheet from being fed back by the reverse rotation of the discharge roller. 2. The paper in the stocker is conveyed toward the printing unit by the reverse rotation of the motor, and the paper is discharged through the printing unit while the print head in the printing unit is driven by the forward rotation of the motor. A paper transport mechanism used in a one-motor type printing apparatus, which is in pressure contact with the paper in a stocker and is provided with only a reverse rotation operation of a motor, and a downstream side of the paper feed roller in a paper transport direction. A drive roller provided in combination with a pinch roller and to which forward and reverse rotation operations of the motor are transmitted, a discharge roller provided in combination with the pinch roller downstream of the drive roller in the paper transport direction, and a discharge roller driven Power transmission means for transmitting the rotation of the motor to the discharge roller so as to rotate in the same direction as the roller; and a discharge roller incorporated in the power transmission means for detecting the forward rotation of the motor. Power to prevent the paper from being reversely fed by the reverse rotation of the discharge roller during the reverse rotation of the motor by blocking the transmission of the reverse rotation of the motor to the discharge roller. Means for transporting paper. 3. The power cutoff means is a one-way clutch that transmits only the forward rotation of the motor, or a pendulum gear that meshes with an adjacent gear when the motor rotates forward and separates from the gear when the motor rotates reversely. 3. The paper transport mechanism according to claim 2, wherein: 4. The printing apparatus according to claim 1, wherein, when printing is performed continuously on two or more sheets, the rear end of the sheet in the conveyance direction excluding the last sheet passes between the driving roller and the pinch roller, and
4. The paper transport mechanism according to claim 2, wherein the rotation is switched from forward rotation to reverse rotation while the sheet is sandwiched between the discharge roller and the pinch roller.